Black''''s veterinary dictionary 21st edition - S pptx

It causes LIGHT SENSITI- SATIONin cattle, sheep, and pigs, especially inAustralia.. Salmonellosis Infection with organisms of the salmonellagroup is of importance from 2 distinct aspects

Gritty, sandy

Sacks

Sacks may be a means of passing infection from

one farm to another, for when empty they are

put to many uses Poisoning has occurred

through contamination of feeding-stuffs by

sacks previously used for sheep-dip For these

reasons, non-returnable paper sacks have

advantages over jute sacks

Sacrum

The part of the spinal column lying between

the lumbar region and the tail It consists

of 5 vertebrae in the horse and ox, 4 in the

sheep and pig, and 3 in the dog and cat, fused

together in each case It is roughly triangular

in shape in all animals, and forms the roof

of the pelvic cavity, lying midway between the

2 ‘points of the hip’ or ‘haunch bones’

Saddle-Sores

Saddle-sores are formed through uneven

pres-sure upon the back by some part of the saddle

They may be found in the middle line,

imme-diately over the upper ends of the spinous

processes; they may occur on either side of

the middle line where the fore-arch of the

saddle-tree presses; or they may be found just

behind the elbow, when they are caused by

badly fastened girths, and are often called

‘girthgalls’

The injuries consist of raw areas from which

the hair has been rubbed or chafed off and,

later, ulcers Alternatively, patches of the skin,

varying in size from 2.5 cm in diameter to

almost 7 cm, may become hard and leathery,

pus being formed underneath These are known

as ‘sitfasts’

TreatmentAttention must first of all be paid

to the saddles They should fit evenly all over

the back, and the stuffing or padding should be

adequate to protect the skin from pressure by

the rigid framework of the saddle-tree The

hol-low of the arch of the saddle should never press

upon the middle line of the back, and the girth

should never be fastened with the skin folded

under it Rest from work will be necessary (See

(Onobrychis sativa) A leguminous forage crop

which fixes its own nitrogen; it contains tannins, so its rumen protein degradability islow (this means that the protein is used moreefficiently); and it does not cause bloat.Voluntary intake by animals is high – intakes

of sainfoin can be 25 per cent higher than that

of ryegrass Furthermore, it is drought-resistant.Unfortunately, sainfoin does not grow as well

as bred strains of grasses, clovers and lucerne;

30 per cent less yield than lucerne is quoted

St John’s Wort

This plant, Hypericum perforatum, which may

be present in hay, does not lose its poisonouscharacter when dried It causes LIGHT SENSITI- SATIONin cattle, sheep, and pigs, especially inAustralia

St Louis Encephalitis

Transmitted by mosquitoes, and caused by aflavivirus, this disease occurs in North andSouth America, affecting wild birds, bats, hors-

es and man (in which it may cause encephalitisand death in the elderly, although only fever inother people)

Salicylic Acid and Salicylates

Originally derived from the willow (genus

Salix), salicylic acid and its salts have long been

used in pain relief ASPIRIN, which is cylic acid, largely replaced the other salicylates

acetylsali-as pain relievers (see ANALGESICS), and has beengiven in fevers It must be used with extremecaution in cats, which metabolise aspirin veryslowly A standard 250 mg tablet given daily to

a cat may prove fatal in 12 days

Salicylate poisoning has occurred inyoung animals following overdosage.Symptoms include depression, loss of appetiteand vomiting Treatment involves the use of

an emetic or gastric lavage and respiratory stimulants

chick-be phased out within the EU by January 2006

S

Salinomycin poisoning Four hundred

point-of-lay turkeys died within a week after

the introduction of a diet containing 50 ppm

salinomycin

In horses the signs of poisoning are

eyelid-swelling, anorexia, colic, weakness, ataxia

Salivary Glands

Salivary glands include the parotid gland, lying

in the space below the ear and behind the

border of the lower jaw; the submaxillary gland,

lying just within the angle of the lower jaw,

under the lower part of the parotid; and the

sublingual gland, which lies at the side of the

root of the tongue Each of these glands is

paired, so that actually there are 6 glands, not

all of which function at the same time

Salivary Glands, Diseases of

Calculi and tumours may occur In rabies, the

salivary glands must become infected before

transmission of the virus to another host can

occur through a bite (See also MUMPS.) A foreign

body, such as a grass seed, may cause an

obstruction to one of the ducts, particularly in

the dog

Salivary-gland tumours in dogs and

cats are rare The majority of 138 tumours in

dogs (81) and cats (57) involved animals of

10 years of age or more, were malignant and

of epithelial origin (84 per cent) Local

recur-rence after excision occurs frequently, and

metastasis to regional lymph nodes and beyond

is common

Salivation

‘Foaming at the mouth’, to use a colloquial but

apt expression, is seen in the dog, e.g in an

epileptic or other fit (See FITS.) ‘Drooling of

saliva’ is seen in the dog with a bone wedged

across the roof of its mouth, or in a cat with a

needle embedded in its tongue – or in cases of

RABIESin all species

Salivation is a symptom of CHOKING, of

almost any painful condition of the mouth or

tongue, and of poisoning (e.g by benzoic acid

in the cat), arsenic, lead, phosphorus and

organophosphorus compounds; see also TOAD

Salivation is also an important symptom

of FOOT-AND-MOUTH DISEASE, and of other

diseases and conditions mentioned under

MOUTH

Salmincola

Parasites on the gills of salmonid fish which

affect respiration Affected fish show reduced

growth and delayed sexual maturity

‘Salmon Poisoning’ in Dogs

‘Salmon poisoning’ in dogs occurs on thePacific coast of the USA, and is the result of eating salmon or trout infested with the

fluke Troglotrema salmincola, containing a rickettsia The latter, Neorickettsia helminthoeca,

produces a haemorrhagic gastroenteritis which

is usually fatal unless antibiotics are used intime

Salmonellosis

Infection with organisms of the salmonellagroup is of importance from 2 distinct aspects:(1) food poisoning in man; and (2) disease indomestic animals

Salmonella poisoning – routes of infection(seediagram)

In cattle and calves Salmonellosis and brucellosis have 4 points in common – bothdiseases are important from the public healthpoint of view; both can lead to abortion in cattle, to a carrier state likely to perpetuateinfection on the farm, and to considerablefinancial loss to the farmer

While the salmonella group of bacteriaincludes more than 1000 different serotypes,the 2 of most importance to the dairy farmer

are Salmonella dublin and S typhimurium.

Either can produce acute or subacute illness inadult cattle and in calves

S typhimurium infection is of greater

public-health importance, and is a notorious cause

of outbreaks of food poisoning in man S.

typhimurium type 204C has been a major

source of problems in calves bought from kets and is highly resistant to antibiotics Anoutbreak of this same infection involved morethan 200 cows on a single farm, and led to thedeath or slaughter of 29 of them

mar-S typhimurium 104 also has a relatively high

resistance to antibiotics It can result in severe illness and deaths in small groups of cows orcalves; it is the second most common salmonella

in food poisoning

S dublin infection may be associated with

abortion, sometimes without any other toms being observed Animals which recovermay excrete the organisms for years Besidesthis carrier state, which may keep infection

symp-on the farm, there is also a latent carrier state

in which the organism remains dormant withinthe animal until it is subjected to some stress

or superimposed disease, when excretion of the organism occurs and fellow members of the herd become infected

622 Salivary Glands

S

SignsThe 2 infections are usually very similar

and can be distinguished only by laboratory

tests In the acute form of the disease, the

cow becomes dull, feverish, goes off her food,

and the milk yield suddenly drops Scouring is

usually severe, and the animal may pass bloodand even shreds of mucous membrane from theintestine Death may occur within a week

If treatment is delayed, mortality may rise to

70 per cent or so; whereas early treatment can

Salmonellosis 623

S

Salmonella poisoning – routes of infection (With acknowledgements to World Health Organisation, Technical Report No 774.)

An electron-micrograph of Salmonella dublin (Magnification × 50,000.) (Reproduced by courtesy

of the Department of Veterinary Preventive Medicine University of Liverpool.)

bring the death rate down to 10 per cent In

animals which recover, scouring may persist for

a fortnight, and it may be several weeks before

the cow is fit again

The subacute form in adult cattle runs a

milder course and, indeed, the infection may

exist without any symptoms being shown A

latent infection may become an overt one

following stress of any kind or when another

disease becomes superimposed – sometimes

masking the symptoms of salmonellosis itself A

liver-fluke infestation may be a precipitating

factor

Salmonellosis may run through 8 calves out

of a batch of 10, and kill 4 of them Some calves

collapse and die without ever scouring; others

become very emaciated as a result of persistent

scouring Pneumonia, arthritis, and jaundice

may be among the complications; occasionally

the brain is involved, giving rise to nervous

symptoms

S typhimurium infection seldom persists

from one season to another on any particular

farm because there are fewer ‘carrier’ animals

than there are with S dublin; it is often brought

on to the farm by calves bought in from

mar-kets and suffering from the effects of stress,

rough travelling conditions, lack of food or a

change of diet The infection occurs in many

species of animal including, as the name

suggests, mice

S dublin infection arises mostly from other

cattle It can be spread from farm to farm via

slurry and streams Infection may enter even a

closed herd if it is grazing flooded pasture land

Lack of shelter, overcrowding, dirty

sur-roundings, and faulty feeding have all been

implicated in outbreaks In adult cattle, the

fortnight after calving is regarded as a danger

period, especially where the calving has been a

difficult one

S dublin can survive in slurry for at least

12 weeks

It is also known that salmonella organisms

can survive for 6 months or so in dung and

lit-ter, and S dublin can survive for up to 307

days, if not longer, on dung splashes on a wall,

so that thorough cleaning and disinfection of

buildings are necessary, and reliance must not

be placed on a simple ‘resting period’ between

batches of calves

Salmonella organisms may be present in

domestic sewage, and river pollution from this

source has led to outbreaks of salmonellosis in

cattle

Preventive measures include trying to keep

rats and mice off cattle feed, avoiding pig and

poultry effluent for organic irrigation, having

piped drinking water for cattle, and not buying

in through markets or dealers but rather fromfarms with a known health record The earlierhousing of cattle in the autumn may help, and it is important not to neglect liver-flukeinfestation which can sometimes act as a ‘trig-ger’ to outbreaks of salmonellosis in which theinfection was hitherto latent

Treatment Drugs used include antibiotics,potentiated sulfonamides and sulfadimidine

A range of vaccines and antisera-vaccine bined preparations is available for prophylaxis

com-and therapy They usually contain E coli,

Pasteurella and S typhimurium and S dublin

strains

In sheepS typhimurium has caused diarrhoea

and abortion S agona has caused abortion,

death of ewes from septicaemia, death of lambswithin a week of birth, and sometimes diar-

rhoea S dublin is likewise a cause of abortion

In pigsThe term ‘salmonellosis’ is now

usual-ly reserved for a severe septicaemia S cholerae

suis causes this; symptoms include fever,

hud-dling together, purple discoloration of ears,unsteady gait, and sometimes scouring The

624 Salmonellosis

S

Seasonal incidence of salmonellosis (With

acknowledgements to the British Veterinary

same organism may give rise to a chronic

infec-tion with scouring The organism can infect

man

Infection with S dublin sometimes occurs in

pigs, and may give rise to dysentery

More common is infection with S

typhimuri-um This causes fever, scouring, vomiting, and

unsteady gait – usually in younger pigs than the

first-named organism Sulfadimidine has proved

useful in treatment

In horsesS typhimurium has caused serious

outbreaks of illness in young horses Horses

may also be symptomless carriers of this

infection In 1976 an outbreak of S newport

infection caused the death of many horses in

the UK (See also FOALS,DISEASES OF.) Outside

the UK, S abortus equi is a cause of abortion in

mares

Stress, associated with the hospitalisation of

horses, is said to have led to acute enteritis,

often from S senftenberg.

In dogsIllness may be mild, with fever and

malaise; or there may be severe gastroenteritis

and death Many salmonella serotypes infect

dogs It is possible for a dog to become a

symp-tomless carrier of S typhimurium and to infect

man

Feeding raw offal to dogs had been suspected

as an important source of salmonellosis in

Berlin Accordingly, 408 samples of edible offal

(liver, lungs, heart, bovine rumen, and porcine

oesophagus) were examined bacteriologically It

was found that 231 samples (57 per cent) were

infected with salmonella S typhimurium was

the most prevalent of 24 serotypes

In cats Infection with S enteritidis and

S typhimurium may be set up following the

catching of infected rats and mice For this

reason cats should not be allowed to lie on

uncovered food-stuffs Cats may also become

infected through eating contaminated meat

In poultryAs a specific disease, salmonellosis

is rare except in broilers, although it is involved

in numerous other disease conditions Over

50 members of the salmonella group have been

isolated from poultry in the UK, and several

have caused outbreaks of disease in broiler

plants (See PULLORUM DISEASE;FOWL TYPHOID.)

Arthritis, due to a variant strain of S

pullo-rum, gives rise to a mortality of 5 per cent or so,

as a rule, but in one outbreak 200 deaths

occurred in a 1000-bird unit Apart from

lame-ness and swelling of the foot and hock joints,

symptoms include poor feathering and

under-development Death can be expected betweenthe ages of 10 days and 5 weeks

It was found that survivors did not react to a

blood test carried out with standard S pullorum

antigen, but reacted strongly to antigen pared from the variant strain This probablyaccounts for carrier birds having remainedundetected in the past

pre-During a 5-year period, birds in 144 flocks inSweden were given cultures of caecal contents

as a means of controlling salmonella infection

by the competitive exclusion technique In all,2.86 million birds were treated and it was concluded that this treatment was associatedwith a reduction in salmonella infections Noadverse effects were reported

Salmonellae will remain alive for periods of

up to 6 months or more in dung and litter.Therefore such material should be stacked sothat heating occurs; no animals should haveaccess to the heap

As mice may play a significant role in

main-taining S enteriditis infection in flocks, rodent

control and disinfection of housing may beeffective in dealing with the problem

A vaccine prepared from S enteriditis phage

type 4 is available (Salenvac; Intervet)

In ducksSalmonella species sometimes cause

a high mortality in ducklings Fatal cases ofhuman food poisoning have occurred as a result

of infected ducks’ eggs

In geese S typhimuriam may be found in

goslings, affecting only the eye; the vitreousbody is totally destroyed

Public healthAs already mentioned, nellosis is an important cause of food-poisoning

salmo-in man, often leadsalmo-ing to serious illness.Numerous instances linking food-processing

with outbreaks have been investigated S

seften-berg has been linked with isolates from human

beings and a poultry processing plant S.

kiambu and S enteritidis were isolated from

frozen turkeys from the same batch which

caused 64 cases of illness in people S panama and S brandenburg were similarly isolated from

abattoirs/processing plants and human beings

S agona is a public-health problem in the

USA, the UK, the Netherlands, and Israel Ineach country the original source of the infectionwas Peruvian fish meal used in animal feeds Ithas been demonstrated that animal feeds canplay an important role in the transmission ofsalmonellosis to man

Unpasteurised milk is another source ofhuman salmonellosis A 65-year-old woman was

Salmonellosis 625

S

infected in this way, and was ill with diarrhoea

and meningitis After her death a brain abscess

was found Both the latter and meningitis

are ‘rare complications of salmonellosis in

man’ Seventeen other people were ill with

salmonellosis from drinking the unpasteurised

milk

Viable salmonellae were found in the meat

fraction of domestic refuse from 120 houses

This source could provide a reservoir of

infec-tion accessible to wild animals Tipping should

be carefully controlled, and refuse covered

immediately

The protective gloves, worn by a veterinary

surgeon while calving a cow, unfortunately

burst Within 48 hours numerous non-pruritic

papules had appeared over both arms,

especial-ly the upper arm, where the gown cuffs had

chafed the skin The papules developed into

pustules which burst and resolved in

approxi-mately 10 days without treatment No other

symptoms were observed

A pustule was swabbed and a pure growth of

Salmonella species was recovered.

(See also under SAUSAGE.)

Saloliths

These are CALCULI, found mainly in STENSON’S

DUCTof horses

Salpingitis

Salpingitis is inflammation in the Fallopian tubes

or oviducts, sometimes the cause of sterility in

cattle (See INFERTILITY.)

Salt

A chemical substance in which a metal is

sub-stituted for the hydrogen of an acid

Sodium chloride (common salt)

(NaCl)is an essential ingredient of body fluids

Sodium depletion results, ultimately, in

circula-tory collapse

Salt is an appetiser, and commonly

incorpo-rated in animal feeds in carefully measured

proportions Ruminants will avidly consume

salt; any excess is harmlessly excreted in the

urine and faeces

Salt licksIt has been suggested that a 500-kg

(10-cwt) cow needs 30 g (1 oz) of salt a day

for maintenance and a further 3.5 g (1⁄8 oz)

for 4.5 litres (1 gallon) of milk produced

Therefore, a 3200-litre (700-gallon) cow

requires about 14 kg (30 lb) of salt yearly

On some pastures, or under some systems of

management, cattle may not obtain sufficient

salt To obviate this danger, salt licks are

commonly provided In some salt licks traces

of iodine are incorporated, together with othertrace elements such as copper, manganese,cobalt, and magnesium (See ‘LICKING SYNDROME’.)

Salt Poisoning

Salt poisoning has been reported in both pigs and poultry It is essential that pigs are notkept short of water, or given food that is toosalted

An outbreak, reported from Scotland,involved piglets aged 6 weeks brought indoorsfrom field arks at weaning A proprietary mealwas fed dry The water bowls in the house werenot very accessible, and some of the piglets werenot strong enough to depress the levers Twodays after being housed, 23 out of the 32 pigletswere showing symptoms of salt poisoning, andsome died

SignsOften a number of pigs are found deadwithout signs having been observed, theremainder being weak and very thirsty.Vomiting and diarrhoea may occur (For othersigns, see under MENINGOENCEPHALITIS.)

In poultry, adult birds show excessive thirstand diarrhoea, with sometimes cyanosis of thewattles, somnolence, and sudden death Inyoung birds gasping and ascites may occur

Samoyed

A medium-sized breed of dog characterised bythick straight cream or white hair Like thechow-chow, they tend to be ‘one-person’ dogs.Haemophilia has been recorded; pulmonicstenosis may be inherited

COLICwith impaction

Cattle feeding on the seashore take in tities of sand, which in some cases may be sogreat as to hinder the movements of the rumen(where the sand always collects), and, by upset-ting digestion, may cause unthriftiness andeven emaciation

quan-Sand Tampan (Ornithodorus Savignyl)

(see TICKS– Family Argasidae)

at some part of the wall of the hoof, extending

downwards from the coronet, and usually

involving the whole of the thickness of the wall

Causes Anything which interferes with the

proper nutrition of the horn at the coronet

predisposes to sandcrack, the actual splitting of

the horn occurring as the result of the strains

put upon the foot Treads on the inside of the

coronet, occasioned by hurried turning when at

work, are frequent causes in the fore-feet, and

continual pressure on the coronary matrix by

the 2nd phalanx, especially when the toes have

been allowed to grow too long, appears to be

the commonest cause in the hind-feet A

predisposition to sandcrack may be inherited

With all cases it is advisable to place the

ani-mal under veterinary care (See HOOF REPAIR.)

These are natural detergents, present in some

plants such as corncockle and soapwort

Saponins contain a sugar and a steroid-like

compound, and with water form a lather

Poisoning by them results in gastroenteritis

The central nervous system may also be

affect-ed, with consequent paralysis Saponins break

down red blood cells In the USA the leaves and

nuts of the tung tree, grown for the sake of its

oil, can cause fatal poisoning

Saprolegnia

A fungus that can infect fish It is sometimes

found as a secondary infection to another

con-dition such as ulcerative dermal necrosis in

salmonids, and autumn aeromonad disease in

adult brown trout The infection can be

con-trolled by bathing the fish in zinc-free malachite

green but the healing process is prolonged In a

salmon hatchery, it is important to remove dead

and infertile eggs as these can be invaded by the

fungus and passed on to healthy eggs

Sarco-Sarco- is a prefix signifying flesh or fleshy

SarcolemmaThe membrane covering each

voluntary (striated) muscle fibre

Sarcocystis

A genus of protozoal, coccidian parasites having

a 2-host life-cycle Carnivorous animals such asdogs, cats and foxes ingest the cysts when eatinginfected flesh of cattle, sheep, pigs and horses.Human infection also occurs, and sarcocystis is

a zoonosis (see ZOONOSIS)

While the cysts in the intermediate host’smuscles may not have any serious effect uponhealth, the second-generation schizonts are certainly harmful – damaging the endothelium

of blood vessels, and causing serious illness inmany cases

Signs Cattle showed loss of appetite, fever,anaemia, and wasting, after ingesting sporocystsfrom canine faeces, and some cattle died within

33 days Sarcocystosis has also killed sheep

In horses, signs of central nervous system damage may be seen, as well as signs of muscleinflammation, resulting in lameness

PrevalenceIn Europe 61 per cent of tered cattle have been found to be infected InGermany a prevalence rate of 5 per cent in pigshas been recorded

slaugh-Human sarcocystosis may give rise toabdominal pain, diarrhoea, fever, tachycardia,and an increased respiratory rate

A fibroma-like sarcoid is perhaps the mostcommon tumour of equines, especially olderones, occurring on limbs or head Believed to

be caused by a virus, the equine sarcoid monly ulcerates and recurs following surgery.Cryosurgery may be tried, or a BCG vaccine;the latter may be more successful in donkeys Aguarded prognosis should be given

com-Bovine papillomavirus is involved in theprocess by which sarcoids develop from normalequine fibrous tissue

called scabies – and is caused by the parasitic

mite S scabei (See MANGE.) Cats are only very

rarely infected

Sarcosporidia, Sarcosporidiosis

(see SARCOCYSTIS)

Sars

A form of AVIAN INFLUENZAthat is

transmissi-ble to man, often with fatal results Outbreaks

occured in several Far Eastern countries in

2004; many poultry flocks were destroyed in an

attempt to prevent the disease from spreading

Fears that migrating wild fowl would carry the

SARS virus to Western Europe led ??? consider

preventive measures

Sausage

Discarded portions of sausage, or sausage-skin,

can be a source of infection when fed, unboiled,

to pigs, etc Foot-and-mouth disease has been

transmitted in this way African swine fever and

swine fever could similarly be spread by this

means (See SWILL.)

The incidence of salmonella-contamination

of pork and beef and pork sausages taken from

a large factory during the course of production

was 65 and 55 per cent respectively The

salmo-nella serotypes isolated (in descending order

of incidence) included Salmonella derby,

S dublin, S newport, S stanley, S typhimurium,

S heidelberg, S infantis and S agona.

Savaging of Litters by Sows

Various causes of this have been suggested,

including: an inherited tendency; absence of

any straw for nesting purposes; a painful udder;

insufficient time to have become used to her

farrowing quarters; and fright resulting from

the use of a farrowing crate (See PIGS,SEDATION

OF.)

Sawdust

(see under BEDDING and MASTITIS)

Sawflies

Four-winged insects which have a saw-like

ovipositor The larvae can cause poisoning if

SignsDepression, anorexia, muscular

incoor-dination with a difficulty in rising to their feet

Autopsy Findings Liver necrosis, petechialhaemorrhages, and sometimes degeneration ofthe kidney tubules

Inflammation between the digits of young

sheep resulting from infection by Bacteroides

nodosus; it causes acute lameness Its onset is

said to be associated with frosts and moisture.Recovery may occur spontaneously under dryconditions The term is vague, however, and hasbeen used to include the non-progressive

‘benign’ form of foot-rot It has to be tiated from foot-and-mouth disease (See also

differen-‘SCAD’;OVINE INTERDIGITAL DERMATITIS.)

The name given in human anatomy to a small

bone present in the carpus and tarsus In the

racing greyhound, fracture of the right hind

scaphoid is a common accident Treatment has

included the removal of bone fragments and the

successful insertion of a plastic ‘scaphoid’

Scapula

The scapula is the shoulder blade – the large,

triangular, flat bone that lies on the outside of

the front of the chest, to which are attached

many of the muscles that unite the fore-limb to

the trunk

Scheduled Diseases

(see under NOTIFIABLE DISEASES)

Schistosomiasis

Infestation with Schistosoma worms or flukes,

which are also known as bilharzia worms They

inhabit the portal and mesenteric veins mostly,

one species preferring veins of the urinary

blad-der, and another the veins of the nose Cattle

and sheep and virtually all domestic animals,

and man, may become infested

Several species have been reported from

mammals in India, Africa, and Europe S bovis

may cause anaemia, emaciation and death of

cattle in Africa, or the infestation may be

sub-clinical In India S nasalis may produce a nasal

discharge and difficulty in breathing, with

sometimes the formation of a granuloma In

the Far East S japonicum occurs in

water-buffa-lo and infests man, in which the disease is very

serious

The life-cycle differs from the typical case, in

that the free cercaria may pierce the skin of its

host instead of being swallowed

The sexes are separate, and are usually found

with the female lying in a groove formed by the

incurved edges of the male

ControlProvision of clean drinking water and

treatment of pasture with molluscicides such

as copper sulphate to kill the intermediate

host will reduce infection However, such

mea-sures are rarely practicable in affected areas

Drugs such as praziquantel may be effective in

treatment

Schistosomus Reflexus

A deformity of the bovine fetus, in which the

spine is bent, so that head and tail curve

towards each other, causing dystokia Fetal

intestine may be visible at the vulva, or located

in the vagina

Schmorl’s Disease

Schmorl’s disease is a disease of rabbits, ing areas of necrosis of skin or mucous mem-

involv-brane, and caused by Bacteroides necrophorus

(often after the animal’s resistance has been lowered by some other pathogen)

Schnauzer

A German breed of dog with wiry coat thatforms characteristic eyebrows, mouth and chinwhiskers There are miniature, standard andgiant forms The standard has fewer defectsthan the miniature, which is predisposed tocataracts and progressive retinal atrophy

Schradan

An organophosphorus insecticide used in culture and a potential danger to farm livestock.(See also PARATHION.) Symptoms of poisoningmay include vomiting, lachrymation, saliva-tion, straining, twitching, distressed breathing,and coma

Scirrhous Cord

Scirrhous cord is a condition in which there is achronic fibrous enlargement of the cut end ofthe spermatic cord following castration In mostcases the castration wound does not completelyheal, but a small sinus discharging a thick whitepus persists The discharge may cease later, butthe swelling of the cord goes on increasing slow-

ly in size, until eventually it may be nearly aslarge as a man’s head In extreme cases theswelling extends upwards through the inguinalcanal and into the abdomen and a mass weigh-ing as much as 45 kg (100 lb) has occasionallybeen encountered in the horse on post-mortem examination Treatment is entirely surgical

Scirrhus

Scirrhus is a term applied to a growth or toother hard fibrous conditions of various organs

Sclera (Sclerotic Coat)

Sclera (sclerotic coat) is the outermost hardfibrous coat of the EYE

Sclera (Sclerotic Coat) 629

S

Scleritis means inflammation of the sclerotic

coat of the eye

A soil-dwelling fungus which may infect

salmonids, causing swelling of the skin and, if

it penetrates the body, in the kidney

Scoliosis

Lateral curvature of the spine

Scombiotoxic Poisoning

Scombiotoxic poisoning is a type of

food-poisoning which occurs as a result of eating

fish that contains large amounts of histamine

The histamine is produced by bacterial

degra-dation of histadine when the fish – particularly

tuna, bonito and mackerel, and also sardines,

pilchards and herrings – are stored for

pro-longed periods at elevated temperatures The

symptoms commonly found are rash,

diar-rhoea, flushing and headache

Scorpions

Their venom affects the nervous system,

caus-ing pain, salivation, erection of hair, dilated

pupils, increased blood pressure, and muscular

of age At around 2 years of age the dog may have outgrown ‘Scottie cramp’ The cause isunknown Intravenous injections of calciumborogluconate, or parathyroid extract adminis-tration, have been recommended The conditioncould be eliminated by breeders

Scottish Fold

A breed of droop-eared cat Although no majorproblems should be seen, owners are advised tocheck regularly for ear mites and infection.Some individuals may have a thickening andshortening of the tail that may be accompanied

by thickening of the limbs and overgrowth ofcartilage at the joints

Scottish Terrier

A small wiry dog, black, white or brindled VonWillebrand’s disease may be inherited and thebreed is prone to craniomandibular osteopathy,deafness and Perthe’s disease Intervertebral discdisease may be found in the neck region; it maypossibly be due to the weight of the head inrelation to the body in some individuals

630 Scleritis

S

Scours, Scouring

(see DIARRHOEA)

Scrapie

Scrapie is a disease of sheep mainly confined to

the district of the English and Scottish Borders,

to Spain, France, and Germany Sheep

import-ed into Australia, New Zealand, Canada, and

the USA have brought the disease with them

Australia and New Zealand are believed to have

quickly eradicated the disease Scrapie is a

NOTIFIABLE DISEASEin the UK, which operates

a compulsory slaughter policy for infected

sheep

Scrapie, BSE and other ‘prion’

diseases It is possible that scrapie has a

relationship with the human diseases kuru,

Creutzfeldt-Jakob disease and

Gerstmann-Straussler-Scheinker syndrome Material from

scrapie-infected sheep, rendered and used in

dairy cattle concentrates, is believed to be the

origin of BSE in cattle (See BOVINE SPONGIFORM

ENCEPHALOPATHY.)

DiagnosisOne method is to detect

scrapie-associated fibrillar protein (PrP) by means of a

rabbit-anti-sheep PrP polyclonal antibody by

Western blot analysis; but consistent results

have not, it seems, been obtained

Experimentally, scrapie has been transmitted

to goats, mice, rats, and hamsters

Cause An infective agent, possibly a prion

Research at the joint AFRC and MRC

neu-ropathogenesis unit, Edinburgh, found that

crude extracts of scrapie-infected brain

con-tained accumulations of material known as

scrapie-associated fibrils (SAF), which were also

found in scrapie-like diseases

Infection is spread from ewe to lamb and,

possibly, by contact with fetal fluids Signs take

about 2 years to appear

A long-term DEFRA research project is

investigating the causes, disease process and

epidemiology of scrapie, and the genetic factors

making some sheep more susceptible than

others The aim is eradication of the disease

from the UK (See NATIONAL SCRAPIE PLAN.)

SignsThe most striking and easily seen

symp-tom of scrapie is the torn, ruffled, and untidy

appearance of the fleece, and when very severe,

the bruised or scratched condition of the skin

In many cases, especially those occurring

dur-ing the late sprdur-ing, the fleece may be almost

entirely rubbed off against fences, posts and

trees or may be greatly removed by the mouth

In addition, the condition of the sheep is worthy; whereas the remainder of the flock may

note-be in fair bodily condition, the scrapie sheep arethin, gaunt, and apt to become weak on theirlegs, lagging behind when going uphill, and losing their foothold when descending.Muscular tremors are often seen, and later there

is evidence of intense itching

Occasionally, when startled – as, for instance,when being moved by dogs, or when a gun isfired near the unwary scrapie sheep – convul-sive seizures are seen, usually lasting from 3 to

5 minutes, and leaving the animal temporarilydazed

Screw-Worm Flies

These include Chrysomyia bezziana in Australia,

Cochliomyia hominivorax, C Americana.

The screw-worm (C hominivorax), a

signifi-cant parasite of both humans and animals, hadnot been recorded outside the New World untilits accidental introduction into Libya, probably

in 1988–9 Hundreds of cases of wound sis including many fatalities were recorded invarious species of domestic animals during

myia-1989 and 1990

An international campaign to eradicate theAmerican screw-worm fly from North Africaappears to be succeeding, according to a bulletinfrom the organisers

The campaign, begun in December 1990,involved the release of sterile male flies import-

ed from Mexico The flies were dispersed by air

at densities of 500 to 1200 per km2over an area

of 40,000 km2 More than 745 million flieshave been used and 40 million a week were dis-persed during the campaign (See FLIES;

MYIASIS;STRIKE.)

Scrotal

Relating to the scrotum

Scrub Typhus (Japanese River Fever)

A disease caused by Rickettsia tsutsugamushi,

and transmitted by mites

Scur

A loose, horny growth, not attached to theskull, at the site normally occupied by a horn in

a horned breed of cattle

A bull calf with a scur, or with a bony berance beneath the skin at the horn site, is not a pure polled animal Without these, a bullcan be expected to breed true as regards the poll character; this can be checked by a proge-

protu-ny test of the bull mated to horned cows – theresult should be polled heifer calves or bull

Scur 631

S

calves with scurs or bony protuberances, but no

calves with horns

Sea Lice

Farmed Atlantic salmon, and sea trout, are

subject to infestation by sea lice (Lepeophthirus

salmonis and Caligus elongatus) with serious

economic consequences Treatment with

para-siticides including hydrogen peroxide and

synthetic pyrethroids such as cypermethrin is

effective, but must be repeated at intervals

depending on circumstances

Seal

A common marine mammal found around the

coasts of Britain and many parts of the world,

favouring colder climates True, or earless,

seals are members of the family Phocidae They

are susceptible to infection by a morbillivirus

similar to that causing canine distemper In

polluted areas, they are liable to suffer mercury

poisoning

Sealyham Terrier

A short-legged breed with a wiry, often white,

coat Retinal dysplasia may be inherited and the

breed is prone to deafness and lens luxation

A source of AGAR; a food grazed by sheep on the

seashore, and sometimes fed to horses and cattle

A source of iodine and other trace elements and

(in the case of brown seaweeds) of vitamins A,

Bl, B2, C, and D Animals do not take readily to

seaweed as a rule, nor are they able to digest it

well at first, but after a few days it usually proves

an acceptable supplement to the ration

The ruminal microflora of sheep feeding

almost entirely on seaweed were devoid of

cel-lulolytic bacteria and anaerobic bacteria which

are so numerous in sheep-grazing pasture

Sebaceous Glands

Sebaceous glands are found in the skin (see

dia-gram under SKIN), and secrete the oily sebum

which prevents excessive dryness of hair and

skin The glands are liable to become invaded

during some parasitic diseases; sometimes a

blocked duct leads to a retention cyst

Seborrhoeais an excessively oily skin due to

over-production by the sebaceous glands

Secretin

A hormone secreted by the mucous membranenear the beginning of the small intestine whenfood comes into contact with the latter Onreaching the pancreas via the bloodstream, thehormone stimulates the flow of pancreaticjuice

Secretory IgA

It has been shown that in some infections, cially those of the respiratory and digestivetracts, immunity is conferred by antibodyfound in the local secretions – and not by the antibody circulating in the bloodstream.For example, the IgA found in secretions isquite different from that found in serum.Secretory IgA is relatively resistant to break-down by digestive enzymes and has an affinityfor mucus (See IMMUNE RESPONSE,IgA.)

espe Sectomy

A word-ending meaning ‘surgical removal of ’

Seed Corn, dressed

A number of substances with which seed cornmay be dressed may be toxic to animals Forexample, corn with a mercury dressing has beenfed to pigs with fatal results

Dieldrin seed dressings lead to poisoning inwild birds and, indirectly, have killed dogs, cats, and foxes which have eaten poisonedbirds (See also under GAME BIRDS.)

Seedy Toe

A condition affecting the hoof of the horse, inwhich there is a separation of the wall from thelaminar matrix below, and the formation in the space so produced of a dry, crumbly, friablevariety of horn, which bears some resemblance

to pumice-stone It may occur at any part of thewall of the foot The cause is uncertain

SignsIn most cases the condition is generallyfirst noticed by the farrier when paring downthe wall prior to fitting a new shoe Lameness isonly seen when the extent of the separation islarge, or when foreign matter becomes forced

up into the space, and causes pressure upon thesensitive matrix

When struck with a hammer the affectedpart of the foot gives out a hollow resonatingnote, and the margins of the separated area canusually be fairly well determined by this means

TreatmentAll the soft friable horn should becleared away and an antibiotic applied within

A suitable shoe should be fitted to cover thebase of the cavity (See HOOF REPAIR.)

632 Sea Lice

S

Selenium (SE)

A TRACE ELEMENTessential in minute

quanti-ties for nutrition, but toxic if fed in excess In

some parts of Britain home-grown animal feeds

may not contain enough selenium, and unless

concentrates are fed as well, nutritional

muscu-lar dystrophy may result The organic form

conjugated to the amino acid methionine is

more easily utilised by animals than inorganic

salts In other areas the soil may contain an

excess of selenium The normal level in animal

feeds should be around 0.2 ppm; the maximum

level of selenium allowed in pig diets without a

veterinary prescription is 0.5 mg/kg, this level

being specified under the Feeding-Stuffs

Regulations 1982

Supplements of selenium can be given not

only in the feed, but also in drinking water, by

subcutaneous injection, by BOLUS, and (for

lambs) by an oral dose

Sodium selenate is used by horticulturists as

an insecticide, and accordingly there is a

possi-bility of toxic effect occurring in animals

Sterility results, and also loss of hair These

symptoms are also observed in parts of the USA

and Eire where the soil contains an excess of

selenium In the acute form of poisoning,

ani-mals may be found wandering aimlessly or in

circles Paralysis precedes death

A horse weighing approximately 450 kg

received 25 mg selenium as sodium selenate

daily for 5 consecutive days The horse became

lethargic, walked stiffly and was unwilling to

undertake pace work The main signs were loss

of hair from the mane and tail, disintegration of

the skin of the lips, anus, prepuce and scrotum,

and separation of the hooves from the coronary

corium There were strong correlations between

the selenium concentrations in blood, hair and

hoof parings

Externally, selenium sulphide is used in

wet shampoos for dogs and cats infested with

fleas, harvest mites, or cheyletiella mites (See also

VITAMIN E;LATHYRISM;MUSCLES,DISEASES OF;

IONOPHORES.)

Retention of placentas in a dairy herd in

the north of England was associated with a

selenium deficiency

Sella Turcica

Sella turcica is the name applied to the deep

hollow on the upper surface of the sphenoid

bone in which the pituitary gland rests

Semen (Seminal Fluid)

Semen (seminal fluid) consists of the secretions

of the accessory sex glands, in which is

found the mature spermatozoa (or sperms)

from the epididymis A single ejaculation by abull may produce semen containing millions ofsperms

The secretions of the accessory sex glands act

as a vehicle for the sperms, probably as a ent, and neutralise any acidity in the femalegenital passages

nutri-The accessory glands are the prostate; the ampullae of the vasa deferens (absent in theboar); the seminal vesicles; and (except in thedog) the bulbo-urethral (Cowper’s) glands situ-ated on either side of the urethra (See also under SPERMATOZOA;ARTIFICIAL INSEMINATION.)

Imports of semen in Britain are subject toDEFRA regulations

Seminal Vesicles

(see under TESTICLE;ACTINOBACILLOSIS)

Sendai Virus

This causes respiratory disease in the mouse but

is most noteworthy for its use in experimentalcell fusion work

Senkobo

Cutaneous streptothricosis, caused by

Dermatophilius congolensis, occurring in tropical

Africa in cattle, sheep, goats, and horses Thehair stands erect and matted on small patchesalong the back Moist, raw areas are left, thencrusts form, and eventually a ‘crocodile-skin’effect is produced The disease occurs in associ-ation with tick infestation, and can therefore

be controlled by means of an ectoparasiticide.(See DERMATOPHILUS.)

Senna

A standardised preparation of this householdlaxative has been recommended in treating orpreventing constipation in pigs – especially inpregnant sows A sublaxative dose of 3 g is recommended during the farrowing period

ly distributed throughout the tissues, and cally every organ is affected by them In mostcases, septicaemia terminates in death Examplesare ANTHRAX;HAEMORRHAGIC SEPTICAEMIA

practi-Septicaemia 633

S

SignsIn many cases, especially when the

ani-mal is in a weakened state, sudden death,

pre-ceded by a very high temperature, may be the

only sign of the presence of septicaemia

TreatmentAntibiotics and/or sulfonamides,

and antisera (where appropriate) are given

Septum

A thin wall dividing 2 cavities or masses of tissue

Sequestrum

A fragment of bone which, in the process of

necrosis, has been cast off from the living bone

and has died, but still remains in the tissues

Sequelae

Symptoms or effects which may follow disease

or injury Thus pneumonia may follow a simple

influenza, and chorea may follow distemper

Seroconversion

The appearance in the blood serum of

antibod-ies following vaccination (or natural exposure

to some infective agent)

Serous Membranes

Serous membranes are smooth, glistening,

transparent membranes that line certain of the

large cavities of the body and cover the organs

that are contained in them The chief serous

membranes are: (1) the peritoneum, lining the

cavity of the abdomen; (2) the pleurae, one of

which lines each side of the chest and surrounds

the corresponding lung; (3) the pericardium, in

which the heart lies; (4) the tunica vaginalis,

one on each side, enclosing a testicle; and (5)

the mesentery supporting the small intestine

Serpulina

A group of spirochaetes which includes

Serpulina hyodysenteriae, the cause of swine

dysentery (See SWINE DYSENTERY;TREPONEMA.)

Sertoli-Cell Tumour

This may be associated in the dog with

femini-sation, urethral bleeding, and urinary

obstruc-tion (See also SPERMATIC CORD,TORSION OF.)

Sertoli Cells

Cells in the testicular tubules to which

sper-matids become attached Their function is

believed to be the nourishment of spermatids

(See diagram under SPERMATOZOA.)

Serum

Serum is the fluid which separates from

blood when clotting takes place It is, in effect,

defibrinated plasma without the red cells,

platelets or white cells (For a description ofplasma, see BLOOD.) (See also ANTISERUM.)

as anaphylactic shock (See HYPERSENSITIVITY.)

is detected at about 6 weeks, and checked againaround 9 weeks, the herdsman can, with a fairdegree of accuracy, be on the look-out for bulling

at or about the 12th week (or 84 to 85 days) Inpractice, most farmers will serve at 9 weeks to try

to maintain a 365-day calving interval Veryearly service may produce prolonged infertility

to the soil: however, passage through worms breaks down the complexes, which canthen be absorbed by animals The process may take several years Horses on pasture werefatally poisoned by cadmium, lead and copper

earth-5 years after sewage sludge was applied More

rarely, the eggs of Taenia sagniata which pass

through the filters in some sewage may be present on pasture and lead to cysticercosis incattle (See also SALMONELLOSIS;SLURRY;COPPER POISONINGin sheep.)

Sex Differentiation

Sex differentiation in the fetus is brieflydescribed under EMBRYOLOGY (See also under GENETICS;CYTOGENETICS;FREEMARTIN.)

634 Septum

S

(see HORMONES)

Sex-Inversion

Animals which at birth, and for a variable

period afterwards, are of normal sexual

struc-ture and function, but which later in life

acquire properties of the opposite sex, are said

to undergo sex-inversion This has been seen in

Ayrshire cows permanently kept indoors (See

also FEMINISATION.)

Sex Pilus

(see PLASMIDS)

Sex, Predetermined, of Calves

(see PREDETERMINED SEX OF CALVES)

Sexual Cycle

(see OESTRUS)

Shar-Pei

A medium-sized breed of dog originally from

China which is characterised by very loose,

infolded skin In the folds, dermatitis may

develop if the care of the dog is less than good

Shavings

(see under BEDDING)

Shearing

In Britain, the usual time for shearing is May in

the southern counties, early June onupland

semi-arable farms, and during July in mountain flocks

The newly shorn sheep is very sensitive to

cold This is particularly so with machine

shear-ing which leaves a fleece of about 6 mm depth

compared with about 12 mm after hand

shear-ing In Australia, late-winter and early-spring

shearing of ewes has led to a high mortality, so

that the practice is being abandoned or the usual

shears replaced by ‘snow combs’ which leave a

longer fleece In Britain, losses of weight or poor

gains in lambs shorn during the summer can

largely be attributed to an effect of cold

Chemical ‘shearing’ Certain drugs, for

example cyclophosphamide and mimozone,

cause the wool to loosen so that it can easily be

plucked It has been suggested that this could

be an economical way of defleecing sheep

However, the sheep is left naked and

unpro-tected against cold It does not seem that the

system has gained wide usage

Sheep, Abortion and

Infertility in

(see ABORTION)

Sheep Breeding and Management

The use of hybrids, referred to under SHEEP,

BREEDS OF(British), is a relatively new trend.Another is the housing of ewes for part of the winter before lambing The number ofsheep per flock has increased and a full-timeshepherd will be looking after more than10,000 breeding ewes

Economic factors have dictated manychanges in traditional sheep management Thesheep market has altered greatly; the demand ismainly for lamb, not mutton However, sheepare still sold through markets on a liveweightbasis and are classed as light (25.5 kg), standard(32.1 to 39 kg), medium (39.1 to 45.5 kg) andheavy (45.6 to 52 kg) Wool is now of rela-tively low value, because of reduced demand.Efficient sheep production depends on rais-ing the productivity of grassland by improvingthe quality and quantity of the grazing andimproving the growth characteristics of thesheep Worming regimes must be established todeal with the infestations that affect all grass-land used for growing young sheep Feed avail-able to the lactating ewe must be of sufficientquality to allow a good supply of milk for twin

or triplet lambs, and limit initial grass uptake.Direct and indirect feed costs (including fer-tilisers, fuel and labour), can account for 60 percent of the cost of sheep production Thisemphasises the importance of the efficiency offeed conversion In lowland flocks, most food isconsumed by the ewes, so the number of lambsweaned per ewe per year is of critical impor-tance Ideally, the aim is for a relatively smallewe, with good milking potential, which can becrossed with a larger, meat-producing, breed toproduce several offspring that grow fast andeconomically

While artificial rearing systems for lambs areused, they are not favoured by most breedersexcept for orphan lambs or those from large litters Most farmers aim to produce 2 viablelambs that can be naturally reared

Housing of sheep (In-wintering)Sheepare frequently housed for part of the year, usually before and after lambing The duration

of housing depends on the area and other management considerations In Scotland, in-wintering of ewes lambing between Decemberand April revives a practice traditional in hillareas until a change was made to winteringthem on lowland pastures That policy provedtoo costly and led to the flocks being kept

on the farms and provided with shelter Winterhousing is also now common on lowland

Sheep Breeding and Management 635

S

farms The ewes are kept in groups of 50 to 70,

lambing at the same time

Housing permits greater attention to feeding

and care at lambing, and leads to less culling

as the sheep are not subjected to the stress of

exposure to severe weather and finding their

own food However, the risk of disease and

mismothering is higher

Portable feeding troughs and racks in sheep

houses can be used as partitions and leave an

unobstructed floor so that pen sizes can be

altered according to requirements The 2 main

types of feeder are a hay rack, with sloping sides

so that seeds do not drop into the sheep’s eyes,

with a concentrate trough below (preferred for

upland sheep); and a box type with a barrier in

front which prevents the ewes from wasting the

forage Troughs should allow a length per ewe

of 23 to 25 cm (9 to 10 in) for hill breeds and

30 to 35 cm (12 to 14 in) for lowland breeds A

supply of fresh (i.e running) water must be

provided; sheep will not drink water that is

even slightly fouled, or warm A raised trough

fed from a slow running tap, with drainage to

the outside, is suitable About 30 cm (12 in) of

trough per sheep should suffice for 40 sheep

Adequate ventilation is essential Yorkshire

boarding to walls is suitable If slatted flooring

is used, care must be taken that updrafts do not

chill sheep and, especially, lambs The slats

must be laid parallel to the door openings

Lamb survivalLambs have the highest

post-natal mortality of all the main farm species

This is partly because they are very susceptible

to hypothermia caused by exposure, or lack of

food Problems arise when the environment is

colder than the critical temperature of the lamb

in the first few hours after birth This is 32°C

(89.5°F) for heavy lambs and 37°C (98.5°F)

for light lambs As most lambs are born at

ambient temperatures well below this, they

have to increase their metabolic rate to

main-tain body temperature Wind chill factor can

reduce the effective temperature considerably A

wind speed of 20 km/h (12 mph) can have a

cooling effect of up to 20°C (68°F) or more if

there is rain Even when a lamb survives such

conditions, it will have suffered a major drain

on its bodily reserves, mainly in the form of fat

In bad conditions these may be used up in

between 5 and 17 hours

While a lamb will normally begin to

replen-ish its store of energy within an hour of birth by

sucking, work in Australia has shown that the

urge to do so is reduced if its body temperature

falls below 37°C In some breeds of sheep, such

temperatures occur in weather not unusually

severe for March and April in Scotland So coldnot only increases the demand for energy, butmay prevent that demand from being met.Starvation exaggerates the effect of cold byreducing heat-production capability, so increas-ing the risk of death from hypothermia

It may be possible to breed for greater ablity

to survive under harsh conditions Experimentssuggest that there are significant differencesbetween breeds in their tolerance of body cool-ing; and within breeds, some individual sheephave a cold-resistance several times greater thanthat of other individuals Preliminary trials haveindicated that this character is moderately wellinherited

Lambs require between 180 and 210 ml ofcolostrum per kg bodyweight during the first

18 hours after birth, to provide sufficient fuelfor heat production; and immunoglobulins forprotection against infections

Ewes which are well fed during late

pregnan-cy produce more colostrum than their lambsneed; those with singletons have enough for a2nd lamb By contrast, most underfed ewes donot produce enough colostrum

Colostrum can be readily obtained by handmilking and stored for subsequent use Yields aremarkedly increased when milking is preceded by

an oxytocin injection

Life-saving techniqueson the farm Thefollowing recommendations have been made bythe Moredun Institute, Edinburgh Two dangerperiods should be recognised: (1) from birth to

5 hours afterwards; and (2) 10 hours to 3 daysafter birth

During the 1st period, moderate mia (a body temperature of 37°to 39°C; 98.5°

hypother-to 102°F) usually responds to drying the lamb,feeding it colostrum by stomach tube, andmoving it to shelter along with the ewe Serioushypothermia (below 37°C; 98.5°F) requires inaddition that the lamb be warmed in air at

37°C (98.5°F) to 40°C (104°F) until its bodytemperature has reached 37°C (98.5°F) Whenremoved from the Moredun-type bale-warmer(heated by a domestic fan-heater), the lamb isthen given colostrum and, if strong enough

to suck vigorously, can be reunited with theewe If not strong enough, the lamb must behoused for a day or two in its own cardboardbox in an intensive care unit There colostrum

is given 3 times daily, and warmth provided by

an overhead infra-red lamp

During the 2nd danger period, when serioushypothermia is then usually due to depressedheat production as a result of starvation, andoften complicated by low glucose levels in the

636 Sheep Breeding and Management

S

blood, treatment consists of drying the lamb, the

injection of glucose, and warming – in that order

Further details of bale warmers, lamb

warm-ing boxes, the Moredun lamb thermometer

(which indicates by flashing, coloured lights

whether a lamb has hypothermia, and if so how

badly), and techniques can be obtained from

the Moredun Research Institute,Pentlands

sci-entific Park, Bush Loan, Penicuik, Midlothian

EH26 QPZ

Worm control Most sheep at pasture are

infected with roundworms These, if numerous,

can cause outbreaks of scouring and obvious

unthriftiness Subclinical infestations of the

stomach or intestine can reduce the weight gain

of growing lambs by 20 to 50 per cent (See

WORMS,FARM TREATMENT AGAINST.)

Winter feedingResearch has indicated the

wisdom of hand feeding with starchy

concen-trates (rather than high protein or highroughage rations) to obviate the hill ewe burn-ing up her own tissues in order to keep warmand alive during very cold weather (See under ABORTION,FEED BLOCKS.)

For other aspects of sheep husbandry, andrelated health and disease problems, see ABOR- TION;BARLEY POISONING;BRACKEN POISONING;

‘BROKEN MOUTH’;CASTRATION;CLOTHING OF ANIMALS; COBALT; COLOSTRUM; CONTROLLED BREEDING; COPPER; COPPER POISONING; DIET AND DIETETICS;DIPS AND DIPPING;DOCKING,

DRENCHING;EXPOSURE;FEED BLOCKS;FLEECE,

FLUSHING OF EWES; GENETICS; HOUSING OF ANIMALS;INFECTION;INFERTILITY;ISOLATION;

LIGHTNING STRING;LUMPY WOOL;NOTIFIABLE DISEASES; OESTRUS; PARASITES; PARTURITION,

DRUG- INDUCED; PASTURE, CONTAMINATION

OF; PASTURE MANAGEMENT; POISONING; WEED; SHEARING;SHEEP, DISEASES OF; SHEEP- DOGS; SOIL-CONTAMINATED HERBAGE; STELL;

SEA-Sheep Breeding and Management 637

Pur lamb

Heeder

Weaning Hogg (also used Wether hogg Gimmer hogg Hogget wool is wool of

Hogget (also used Wedder hogg Ewe hogg

for the female)

Diamond ram Wedder hogg Double-toothed ewe to a ram is a ‘yield

Dinmont ram tup Two-toothed Double-toothed gimmer’ (Scotland)

Gimmer Second to Two-shear ram Four-toothed Two-shear ewe A ewe which has ceased

breeding flock she is

a ‘draft ewe’ or a

‘draft gimmer’

Third to Three-shear ram Six-toothed wether Three-shear ewe

fourth Three-shear tup Three-shear wether Winter ewe

Afterwards Aged tup or ram Full-mouthed, Ewe After fourth shearing

full-marked or Ewe ‘aged’ or ‘three-winter’ aged wether

or wedder

STOCKING RATES; STRESS; TRACE ELEMENTS;

TROPICS; VAGINA (for rupture of ); VITAMINS;

WATER;WEANING;WOOL BALLS;WORMS,FARM

TREATMENT AGAINST

Clipping (see SHEARING; CLOTHING FOR

ANIMALS; WOOL SLIP)

Sheep, Breeds of

IntroductionSheep are maintained,

general-ly speaking, with the object of producing both

wool and meat In some countries’ ewe’s milk is

valued for cheese-making In the UK the

impor-tance of the fleece tends to be disregarded

Hardiness, prolificacy, milking capacity of

the females, and activity are all important

What will constitute the most profitable type

must be carefully considered in relation to local

conditions

British breeds of sheepBritish breeds –

some 40 are registered – offer a wide choice of

types, adapted to almost every conceivable set of

conditions under which sheep are maintained in

the country, from the highest mountain grazings

in Scotland and Wales to the richest lowland

pastures, or the dry arable farms of the Wolds

However, crossbreeds are increasingly popular

Cambridge This breed was developed at the

University of Cambridge by Professor John

Owen in collaboration with Alun Davies The

breed is now regarded as one of the most

pro-lific in the world with litter sizes of 1.7, 2.5 and

2.9 for 1-, 2- and 3-year-old females

respective-ly Both sexes are polled, ewes weighing 70 kg

(154 lb) and rams 90 kg (98 lb) (See also TEXEL;

COOPWORTH.)

The British breeds are commonly classified

as Longwools, Downs, other Shortwools, and

Mountain breeds

Longwool breeds include Leicester, Border

Leicester, Lincoln, Wensleydale, Kent or

Romney Marsh, Devon Longwool, South

Devon, and Roscommon

Downs breeds include Southdown, Suffolk,

Hampshire, Dorset Down, Shropshire, and

Oxford

Other Shortwool breeds include Dorset

Horn, Wiltshire Horn, Ryeland, Devon

Closewool, and Kerry Hill

Mountainbreeds include Scottish Blackface,

Cheviot, Swaledale, Herdwick, Lonk, Welsh

Mountain, Exmoor, and Dartmoor

UK sheep population A rapid rise insheep numbers followed the imposition of dairymilk quotas, plus the granting of various subsidy payments At December 1994, MAFFrecorded 29.5 million of which 20.1 millionrepresented ewes in the breeding flock Thesummer census annually lists the population

at 35 to 40 million However, the virtual collapse of the sheep market in the later 1990sled to a drop in numbers A further fall fol-lowed the foot-and-mourh diseases outbreaks

of 2001, since when restocking has revivednumbers

Sheep Dipping

(see DIPS AND DIPPING)

Sheep, Diseases of

(see under ABORTION; ACTINOBACILLOSIS;

ANTHRAX; ARTHRITIS; BALANITIS; BLACK EASE; BLACK-QUARTER; BLOUWILDEBEESOOG;

DIS-BLUE TONGUE;BORDER DISEASE;BRAXY;‘CAPPIE’;

CASEOUS LYMPHADENITIS;ENTEQUE SECO;EYE DISEASES OF;FOOT-AND-MOUTH DISEASE;FOOT ROT; GAS GANGRENE; HYPOMAGNESAEMIA;

JAAGSIEKTE;JOHNE’S DISEASE; JOINT-ILL; LAMB DYSENTERY; LIVER-FLUKE; LOUPING-ILL; MILK FEVER;MOREL’S DISEASE; OVINE EPIDIDIMYTIS;

OVINE INTERDIGITAL DERMATITIS; TODIRUS; PARASITES; ‘PINING’; PNEUMONIA IN SHEEP; PREGNANCY TOXAEMIA; PULPY KIDNEY;

NEMA-‘REDFOOT’;‘RINGWOMB’;SCALD;SCRAPIE;SHEEP SCAB;SWAYBACK;TICKS;TICK-BORNE FEVER OF SHEEP; TOXOPLASMOSIS; UDDER, DISEASES OF;

WATERY MOUTH;WESSELSBRON DISEASE; also ZONA INFECTION; ENZOOTIC OVINE ABORTION;

ARI-HAEMORRHAGIC SEPTICAEMIA; MAEDI/VISNA;

‘MILKSPOT LIVER’;PULMONARY ADENOMATOSIS;

RIFT VALLEY FEVER;ULCERATIVE DERMATOSIS and under RAM.)

Sheep Health Scheme

A preventive medicine and productivity toring scheme for maintaining herd health; it isoperated by Scottish agricultural colleges APremium Health scheme is operated for flocksseeking accreditation as free from chlamydialabortion A maedi/visna accreditation scheme

moni-is also available; it involves certification by aveterinary surgeon that movement records havebeen checked, flock security rules obeyed andblood samples taken

Sheep Ked (Melophagus Ovinus)

Sheep ked (Melophagus Ovinus) is a winglessblood-sucking parasite (See KED.)

638 Sheep, Breeds of

S

Sheep, Legislation Affecting

Agriculture (Miscellaneous Provisions) Act

Foot and Mouth Order 1983

Fresh Meat (Hygiene & Inspection)

Regulations 1995

Market Sales and Lairage Order 1925

Products of Animal Origin (Import & Export)

Regulations 1992

Protection of Animals Act 1911

Protection of Animals (Anaesthetics) Act 1954

Sheep Scab Order 1997

Specified Diseases (Notification & Slaughter)

Order 1991 (amended 1992)

Veterinary Surgeons Act 1966

Welfare of Animals at Markets Order 1990

(amended 1993)

Welfare of Animals (Transport) Order 1997

Welfare of Livestock (Prohibited Operations)

Regulations 1982, 1987

Welfare of Livestock Regulations 1994

Zoonoses Order 1989

Sheep, Names Given According

to Age, Sex, etc.

There are probably more names for any given

class of sheep than is the case among any of the

other domesticated animals, and it is almost

impossible to give a list that will include all the

various designations that are used, but the table

gives a list of commoner terms

Sheep Pox

(see POX)

Sheep Scab

The popular name for psoroptic mange Sheep

scab was formerly a notifiable disease in the

UK, from where it was eradicated in 1952 It

reappeared in 1973 and, following the abolition

of compulsory dipping, has again become a

serious problem In the late 1990s, as many as

25 per cent of sheep pelts showed evidence of

damage associated with scab Although sheep

scab is no longer a notifiable disease, control is

exercised through local authorities It is anoffence under the Protection of Animals Actsand the Welfare of Animals (Northern Ireland)Act 1972 to expose an infected sheep for sale;the charge would be one of causing unecessarysuffering.(see MANGE– Mange in sheep)

Sheepdogs

Sheepdogs are popularly regarded as ally healthy, but a survey in Scotland showedthat at least 11 per cent were suffering from

exception-‘BLACK TONGUE’ as a result of an inadequatediet On average, this consisted basically of 225

g (8 oz) oatmeal, 225 g (8 oz) maize, and (by nomeans always) 225 ml (8 oz) of milk; the first 2ingredients being made into a brose or mash bypouring on boiling water The occasional rab-bit, or piece of boiled mutton from a deadsheep, or – at lambing time – the afterbirths,were not sufficient to prevent ‘black tongue’.Sheepdogs may walk or run 90 miles per day

at lambing time and must have meat if staminaand health are to be maintained Even fishmeal

is of service – also dried blood – if meat or fishare unobtainable (See also under GID;RICKETS.)Sheepdogs may become infected with brucel-losis as a result of eating infected cattle after-births; through eating dead sheep they maybecome infested with the tapeworm causing

HYDATIDdisease Regular worming is essential.(See also ORF;ANTHRAX;BOTULISM.)

Sheep, Winter Coats for

(see CLOTHING OF ANIMALS)

Shelters, Need for

(see under EXPOSURE,TROPICS; also STELL)

Shepherds

Occupational hazards include the following diseases: CAMPYLOBACTER INFECTIONS;

CHLAMYDIA; HYDATID DISEASE; LISTERIOSIS;

LOUPING-ILL; ORF; PASTEURELLOSIS; Q FEVER;

SALMONELLOSIS; TOXOPLASMOSIS (See also ZOONOSES.)

Shepherdesses, if pregnant, are at risk whenhelping with lambing (See CHLAMYDIA.)

Shetland Sheepdog

A small breed resembling a toy rough collie.Progressive retinal atrophy and distichiasis areinherited dominat traits and collie eye anomalyand patellas luxation are recessive traits.Haemophlia and deafness may also be found

Shigellosis

Infection by one of the Gram-negative Shigella

bacteria (See Sleepy foal under FOALS,DISEASES OF

– Septicaemia.)

Shigellosis 639

S

Shih Tzu

A small dog with short muzzle and long flowing

hair; it originates from Tibet The breed is prone

to cleft palate and interverbral disc disease

‘Shipping Fever’

A disease of cattle caused by a virus and/or

Pasteurella multocida or P haemolytica.

‘Shipping fever’ is very common in American

feedlots, among cattle 6 months to 2 years

old, and often follows the stress of transport,

castration, de-horning, winter weather, change

of food, etc In the USA the term ‘bovine

respiratory disease complex’ is a synonym (See

PASTEURELLA.)

Signsinclude fever, loss of appetite, weakness,

followed by nasal discharge, a discharge from

the eyes, distressed breathing, coughing, and

signs indicating bronchopneumonia Mortality

is usually 1 to 2 per cent, but may exceed this

if cases are neglected

Treatment And Prevention Antibiotics

and sulfa drugs are used Immunisation has

been tried using myxovirus parainfluenza-3 and

P septica, for example.

‘Shivering’

A nervous disease of horses It runs a

slowly progressive course, and constitutes an

unsoundness

CauseThis is unknown, though it seems that

there may be a hereditary predisposition to it

SignsIn a well-marked case, the muscles of the

hindquarters are seen to quiver or tremble At

the same time, the tail is usually elevated and

also shows the quivering movements In

advanced cases it may be difficult or impossible

to pick up either of the hind-feet, and shoeing

is only accomplished with difficulty When the

hind-limb is raised from the ground during

backing, in many cases it also quivers, or

‘shiv-ers’, and in some instances one or both of the

fore-limbs, or the muscles of the fore-quarter,

exhibit the same feature

Shivering in the dogmay occur,

especial-ly in fox terriers, for no apparent reason and

may be unconnected with either cold or fear At

the prospect of a walk the dog may suddenly

cease trembling

Shock

Shock is, clinically, an abrupt fall in blood

pressure (acute hypotension)

Signsinclude weakness, pale and cold mucousmembranes, subnormal temperature but noshivering; a weak and rapid pulse; shallowbreathing at an increased rate; cold extremities

CauseShock may follow severe trauma, orrhage, surgical operations, a sudden decrease

haem-in the heart’s pumphaem-ing capacity, burns andscalds, toxaemia (See also ELECTRIC SHOCK;ANA- PHYLACTIC SHOCK.) Pain, fright, and any air-way obstruction may exacerbate the condition

TreatmentAlthough corticosteroids are oftenused, it has been stated that there is little or noevidence that they are effective A blood trans-fusion, adrenalin, plasma substitutes based ongelatin and dextrans, and lactated Ringer’s solu-tion given intravenously, may each have a place

necrosis Infection with Fusiformis necrophorus,

Staphylococcus aureus, or Clostridium welchi may

follow

Shying

(see ‘VICES’)

SI Units

The Système International d’Unités was adopted

by the Conférence Générale des Poids et Mesures

in 1960 Based on 7 units – metre, kilogram,second, ampere, degree kelvin, candela, andmole – it admits only 1 unit for any 1 physicalquantity Derived units in any science or tech-nology can be made up from the 7 basic units

640 Shih Tzu

S

by division or multiplication without numerical

factors being involved The SI unit joules

replaces calories The 7 basic SI units and their

symbols are as follows:

(electric current) ampere A

(thermodynamic degree kelvin °K

temperature)

(luminous intensity) candela cd

(amount of substance) mole mol

(See under METABOLISABLE ENERGY.)

Sialocoeles

Cyst-like swellings, usually lined by granulation

tissue rather than epithelium, containing saliva

Sialogogues

Sialogogues are substances which produce a

copious flow of saliva, e.g pilocarpine and

arecoline

Sickness

(see VOMITING)

Sidebones

Ossification of the LATERAL CARTILAGESof the

horse’s foot When this occurs in a young

ani-mal, it is looked upon as an unsoundness In

old horses, all cartilages, not only in the foot,

tend to become ossified as an almost natural

course of events, and sidebones are accordingly

not looked upon as so serious

CausesHeredity is considered as a

predispos-ing cause, but in many instances no such

rela-tionship can be shown It has been suggested

that a vitamin D deficiency in foalhood may be

partly responsible

SignsOrdinarily, the upper part of each

carti-lage can be felt at the coronet as a flexible ridge

or edge, lying immediately below the skin, but

when the cartilage has ossified, this ridge is no

longer flexible, and is more or less thickened as

well In some instances the ossified cartilage can

be easily seen when the feet are viewed from the

front The condition is more common by far in

the fore-limbs, and may occur on the outside or

inside, or in both places, on one or both of the

fore-feet

When sidebones have formed, there is no

lameness, pain, heat, or other signs of

inflam-mation, but when forming, there may be pain

over the quarters involved, and lameness –

characterised by the taking of a shorter step bythe affected foot, and the tendency to do thismay result in a peculiar short and long step

Treatment As a rule, in horses with wideopen feet and well-developed frogs, no treat-ment is required The sidebone does not inter-fere with slow work of a regular nature (See also RING-BONES.)

Side-Effects

The side-effects of a drug are those produced inaddition to that for which purpose the drug isgiven Examples: deafness in humans followingthe administration of streptomycin; moniliasisafter the use of chlortetracycline; aplasticanaemia after the use of chloramphenicol (See also IATROGENIC DISEASE.)

Silage (Ensilage)

Silage (ensilage) is a succulent food It has beenclassified as follows: Grade I containing 15 percent and over crude protein, and made fromyoung grasses, none in flower, clover, lucerne,

or sainfoin in bud stage; Grade II containing

12 to 14.9 per cent crude protein, and madefrom grasses in their flowering stage, lateautumn grass, clover passed full flower, marrowstem kale, pea pods, cereal-legume crops cutwhen cereal is ‘milky’; and Grade III containingless than 12 per cent crude protein, and madefrom seeding grasses, stemmy clover, maize, peahaulm and pods, sugar-beet tops, potatoes.Grade I makes a substitute for cake, whereasGrade III is good enough only as a substitutefor roots, straw, or low-grade hay

Ensilage involves fermentation Lactic, aceticand butyric acids are produced: in good silage,lactic acid predominates Silage with a highbutyric-acid content must be fed with caution,and may be recognised by its to unpleasantsmell and lighter colour – yellowish-greeninstead of dark brown

The Dorset wedge system of silage-makinghas enabled better quality to be achieved

ADAS comments: ‘Most farmers still makesilage at the wrong time.’ This criticism refers tonot cutting at the optimum stage of growth buttending to delay until there is more to cut.Wilting, judicious choice of harvester, type ofsilo, sealing, consolidation, and use of additivesare all being applied by the more progressivefarmers

As with hay, there are extremes of quality

in silage At the Rowett Research Institute cows have maintained a yield of up to 23 litres(5 gallons) daily for 2 months while receiving

no other feed With the average quality silage it

Silage (Ensilage) 641

S

would, however, be unrealistic to expect to be

able to dispense with supplements

Acetonaemia is often seen in cattle receiving

large quantities of silage of low quality Hay

should be made available as well; also 55 g

(2 oz) per head of bone flour with salt added

When self-feeding of silage is practised, care

must be taken that conditions underfoot do not

become dirty and slushy to an extent where

softening of the horn of the hoof occurs and

foot troubles develop

Silage must be free of ragwort (See under

RAGWORT POISONING; also RETICULITIS,

TRAUMATIC.)

Listeria in silageLISTERIOSISin ruminants

has often been associated with silage feeding

In a survey carried out in Scotland, Listeria

monocytogenes was isolated from 2.5 and 5.9 per

cent of samples of clamp silage obtained in two

successive years

Silage Effluent

Silage effluent has been described as one of the

strongest of all agricultural wastes and

pollu-tants Some 16,000 litres (3500 gallons) of clean

water are needed to dilute 4.5 litres (1 gallon) of

silage effluent to bring it to the recommended

level for treated (‘safe’) effluents

In a wet season a 400,000-kg (400-ton)

silage clamp with grass at 1 to 15 per cent dry

matter at ensiling may produce 182,000 litres

(40,000 gallons) of effluent, most of which

discharges in the first month It takes only a

little of this effluent to kill fish and other forms

of aquatic life if it reaches a stream

‘Silent Heat’

(see under OESTRUS DETECTION;INFERTILITY)

Silica Contamination

Silica contamination can be a problem with

sugar-beet tops and other arable residues

Crops windrowed and then picked up may

contain up to 30 per cent silica Direct

load-ing might keep the figure down to 10 per cent

(See also SOIL-CONTAMINATED HERBAGE,SAND,

COLIC.) Silica is silicon dioxide, present in

sand

Silicon

A non-metallic element In the form of silicic

acid or its derivatives, silicon is essential

for growth, and is found mainly in connective

tissue It has been suggested that lack of

sufficient silicon may be a factor in the cause

of atherosclerosis in man (See also SILICA

CONTAMINATION.)

Silicone implant repair A year-oldArabian filly had a depression over its rightfrontal sinus as the result of an injury sustained

6 months earlier when it ran into a steel pipeand the frontal bone had been broken A heat-vulcanised silicone implant was used to repairthe deformity and the normal facial contourwas restored by suturing the sculpted implant

to the periosteum over the defect

Silicone Solution

An anticoagulation solution used in connectionwith blood transfusion apparatus and syringes

to prevent clotting

Simian Haemorrhagic Fever

(see MONKEYS,DISEASES OF; EBOLA VIRUS)

Simmental

A dual-purpose breed of Swiss cattle, now to befound throughout Europe and in the USA InGermany the Simmental has been developedwith emphasis on beef production

Simulium

(see under FLIES) In the UK, the gnat S ornatum,

which breeds in running water and is difficult

to control, sometimes causes eye lesions in cattle

Sinus

Sinus is a term applied to narrow hollow ties (especially in bones) occurring naturally

cavi-in the body, or produced as the consequence

of disease (See SINUSES OF THE SKULL; also FISTULA.)

In pathology, sinus refers to a blind infectedtract, leading from a site of suppuration to thesurface of the skin or of a mucous membrane

Sinuses, Diseases of the

The sinuses of the head are lined with a brane which is continuous with that of thenasal cavities, and which acts as a periosteal covering for the bone

mem-Causes Sinusitis may arise as a result of aspread of inflammation from that affecting the nasal mucous membrane It may followstrangles in the horse; occasionally the cause is

a diseased tooth, the root of which has rated and the pus burrowed through the thinplate of bone that separates the tooth socketfrom the sinus cavity In other cases, the cause

suppu-is a penetrating injury from the outside, such as

is occasioned by a blow on the forehead whichfractures the external plate of bone and allowsthe ingress of infection Animals living near the

642 Silage Effluent

S

seashore or in sandy and windy localities are

sometimes afflicted with collections of fine sand

in the sinuses In sheep, and sometimes in the

horse, sheep-nostril fly larvae of the Oestrus

family may be found in the sinuses, and are

generally associated with pus formation In

dogs especially, but also in other animals,

tumour formation is often accompanied by the

presence of pus in the sinuses, and the

condi-tion may be complicated by a FUNGAL

infec-tion In the dog, a foreign body such as a grass

seed may give rise to the discharge from one

nostril which is characteristic Either cancer, or

a fungal infection which may follow, can lead to

distortion of the dog’s or cat’s face (See also

MITESlinguatula serrate LEECHES.)

SignsThe most prominent sign of the

pres-ence of any amount of pus in the sinuses is

the usually slight, but continual, dribbling of

discharge from one or both nostrils This

discharge is usually more marked when the

animal lowers its head

TreatmentThis consists of opening, under

anaesthesia, the diseased sinus by trephining the

bone over the surface, and irrigation and

evacu-ation of the cavity When a tooth has been the

primary cause of the condition it is extracted,

and its cavity temporarily plugged with gauze

until healthy tissue fills up the space between

the tooth socket and the sinus Parasitic

inhab-itants are removed, either by the injection of

fluids that will kill them, or by picking each out

separately with forceps Chloroforming the

animal will often kill such parasites

Sinuses of the Skull,

The sinuses of the skull, also called the

paranasal sinuses, are directly or indirectly

con-nected with the nose There are 4 pairs: (1)

maxillary; (2) frontal; (3) spheno-palatine, or

sphenoid; and (4) ethmoidal

Sinusitis

Inflammation of the sinuses

Sinusitis, Infectious

A disease of turkeys, poultry and pheasants

caused by Mycoplasma gallisepticum The

obvi-ous sign is a swelling of the sinuses below the

eyes, but the disease will also be present in the

lower respiratory tract While local treatment

(e.g draining the sinuses) is helpful, generally

administration of antibiotics is necessary The

disease is egg-transmitted and may spread from

egg to egg in the hatcher Infected birds always

remain carriers Eradication has been carried

out in the commercial breeding stock of majorsuppliers

Swollen sinuses may also be seen in certainparamyxovirus infections, from which infectioussinusitis must be differentiated

in vitamin E; and if given along with cod-liveroil to beef stores, may lead to cod-liver oil poisoning or MUSCULAR DYSTROPHY

Skim milk is a useful food for pigs, but is notsuitable on its own It can be fed ad lib to suck-ling pigs; weaners may receive 3 litres (5 pints)per day; fatteners from 14 weeks to slaughter,about 3.5 litres (6 pints)

Skim milk is, if from infected cattle, a source

of tuberculosis in pigs, and pasteurisation may

be desirable in many countries

For sows and piglets, skim milk should befresh or completely sour; 0.1 per cent formalin

is sometimes added to skim milk for fatteningpigs

Skin

Skin, the protective covering of the body, iscontinuous at the natural openings with themucous membranes It consists of 2 main lay-ers, which differ in structure and origin

The epidermis This is a cellular layer ofnon-vascular, stratified epithelium of varyingthickness, covering the outer surface of thebody, which presents the openings of the cuta-neous glands and of the hair follicles In ani-mals it is divisible into 2 layers, the outer, hard,dry stratum corneum, and the deeper, softer,moist stratum germinativum The cells of thelatter are pigmented, and by their growth com-pensate for the loss by exfoliation or shedding

of the surface cells from the stratum corneum,which forms the scurfy deposit upon anungroomed horse This inner layer consists ofthe part of the skin which is living, and isformed by several layers of cells set upon thecorium and nourished by it The cells continu-ally multiply, and are slowly pushed upwards to

Skin 643

S

replace the constant wear and tear which occurs

on the cells at the surface There are no blood

vessels in the epidermis, but there is a

ramifica-tion of the surface sensory nerves which supply

the skin with its delicate sense of perception A

blister is a collection of fluid separating the

stra-tum corneum from the strastra-tum germinativum

The dermis (corium)consists of a network

of fibrous tissue and elastic fibres It is very

vascular, contains the hair follicles, the

sudorif-erous (or sweat) glands, and the sebaceous

glands, as well as a certain amount of

involun-tary muscle The most superficial part is known

as the corpus papillare, on account of the

presence of numbers of tiny papillae, which

are received into corresponding depressions in

the epidermis These papillae contain loops of

blood vessels, which nourish the epidermal

cells, and numerous sensory nerves, which act

as tactile organs, affording sensations of touch,

pain, temperature, etc

The sweat glands are situated partly in the

deeper parts of the corium, known as the

tuni-ca propria, and partly below it in the layer of

subcutaneous fibro-fatty tissue In this deepest

layer, which forms the bulk of the skin, or lying

in the deeper part of the corium, there are

cer-tain tactile bodies, known as Pacinian

corpus-cles The fibrous tissue of the skin consists of

interlacing bundles of white fibrous tissue

which form a dense felt-work Here and there

elastic fibres are mixed with them, and theseserve to give the skin its pliability, and at the same time keep it in place and stretched reasonably tightly

HairPractically the whole of the body of eachdomesticated animal is covered by hair, except

in the pig Portions of the skin which appear to

be bare are found on close inspection to be ered with very fine hair of delicate texture Thehairs are constantly being shed and replaced byothers, while at certain periods of the year inthe horse, and to a lesser extent in the other animals, they are cast off in great numbers, andconstitute the ‘shedding’ or ‘casting of the coat’.This normally occurs twice a year – once in theautumn, when it is more marked, and again inthe spring with the first warm weather of theyear

cov-Hairs are of several kinds: in the first placethere are the ordinary hairs which, on account

of the small amount of pigment that each ries, give the coat its characteristic colour; andthere are different kinds of special hairs Amongthese ordinary hairs scattered over almost thewhole body are: tactile hairs of the lips, nostrils,and eyes; cilia, or eyelashes, growing from thefree rim of the eyelids; tragi, in the external ear;and vibrissae, round the nostrils In addition tothe ordinary and tactile hairs, certain regionscarry specially long and coarse hairs, such as themane (juba), the forelock or foretop (cirrus

car-644 Skin

S

The nerve supply to the skin (In Muller, Christensen and Evans, Anatomy of the Dog, courtesy of W B.

Saunders Co.)

capitis), the tail, where the hairs (cirrus caudae)

are very large and long, and the ‘feather’ of the

fetlocks and cannons (cirrus pedis), which gave

the name of this region (fetlock = feet-lock – a

lock of hair on the foot)

Each hair has a shaft, the part above the

sur-face, and a root, embedded in the hair follicle

Below this is a little fibrous papilla possessing

blood vessels, which is capped by the expanded

end of the hair root, and known as the hair

bulb The follicles are set somewhat obliquely

in the corium and at varying depths; the long

tactile hairs reaching down to the underlying

muscle Most of the follicles have little bands of

plain muscle attached to one side, known as

the arrectores pilorum; these serve to erect the

hairs during anger, fear, or extreme cold, and

also to express from the sebaceous gland a small

portion of sebaceous secretion

Glands of the skinare of 2 kinds: sweat

and sebaceous The former are scattered over

the body in nearly all animals, being most

numerous in the horse, and least in the dog

(which is essentially a non-sweating animal),

where the largest are found only on the pads of

the feet Each sweat or sudoriferous gland

consists of a long tube, usually greatly coiled in

its inner part, which has a duct leading up to

the surface of the skin (See PERSPIRATION.)

The sebaceous glands, except in certain

places, open into the follicles of the hairs a

little way below the surface Each consists of

a little bunch of small sacs, within which fatty

or oily material is produced This secretion is

forced from the sacs by the contractions of the

arrectores pilorum muscles, and during exercise

it also escapes on to the shafts of the hairs Its

function is to keep these pliable and lubricated

and prevent them from becoming brittle

through drying A copious secretion from

the sebaceous glands results in a sleek shining

coat, such as is associated with a well-fed and

well-groomed horse

Appendages of the skinIn addition to

hair, the skin possesses certain appendages,

which in reality are modified hair only Thus,

horns, hoofs, claws, nails, ergots, chestnuts, and

other horny structures are closely packed

epi-dermal cells which have undergone

keratinisa-tion or cornificakeratinisa-tion Spurs of poultry are horny

epidermal sheaths covering a centre of bony

outgrowth from the metatarsal in the case of

poultry Feathers are highly specialised scales

The down feathers of the chicken are simple,

and consist of a brush of hair-like ‘barbs’

springing from a basal quill or ‘calamus’ From

the whole length of each barb a series of

small-er ‘barbules’ comes off not unlike the branches

of a shrub The adult or ‘contour feathers’ areformed at the bottom of the same follicles thatlodged the down feathers, which by the growth

of the adult feather become pushed out ofplace At first they are nothing more thanenlarged down feathers, but soon one of thebarbs grows enormously, and forms a mainshaft or ‘rachis’ to which the other barbs areattached on either side From the sides of thebarbs grow the barbules, just as in the downfeathers; and these, in the case of the large wingfeathers (‘remiges’) and the tail feathers (‘retri-ces’), are connected by minute hooks so that thefeather ‘vane’ has a more resistant surface forflight than in the case of the breast feathers, forinstance Moulting in birds occurs periodically,when the bird casts off the old feathers and gets

a complete new set

Functions of the skinThe main use of theskin is a protective one It covers the underlyingmuscles, protects them from injury, and byvirtue of its padding of fat prevents them fromextremes of temperature The hair, fur, wool, orfeathers assist this heat-regulating mechanismstill further, and usually the growth of the coat

is determined by the temperature of the roundings For example, when horses are keptout of doors during winter they grow long thickcoats, while when kept in warm stables and covered with rugs they assume a close sleekcoat: and the same applies to other animals.Heat regulation is one of the most importantfunctions of the skin When cold air, water, orother cooling substances come into contactwith a large area of the skin, the numerousblood vessels of the skin immediately contract,reducing the amount of blood circulating inthem, and therefore reducing the amountwhich will be exposed to the cooling actionfrom outside On the other hand, when the sur-rounding medium is at a higher temperaturethan the normal – i.e when it is approachingbody heat, or rises above it – the blood vessels

sur-of the skin dilate, more blood is brought to thesurface, and this stimulates sweating, or excre-tion; when the perspiration evaporates, espe-cially when the surrounding atmosphere is dry,considerable cooling of the skin surface occurs.(See TEMPERATURE;TROPICS;HYPOTHALAMUS.)

Skin, Diseases of

The majority of the commoner diseases of theskin in animals are due either to parasitic invasion, or to conditions of an allergic origin,e.g eczema These are treated under separate

Skin, Diseases of 645

S

headings – e.g mange, of all varieties, is dealt

with under MITES;ECZEMA;URTICARIA;

RING-WORM; ACNE; see also TUMOURS; IMPETIGO;

POX; BRIDLE INJURIES; SPOROTRICHOSIS;

SWINE ERYSIPELAS;LIGHT SENSITISATION;

DER-MATOPHILUS; GRANULOMA; ABSCESS;

HYPERK-ERATOSIS; LUPUS; AUTO-IMMUNE DISEASE;

CUTANEOUS ASTHENIA

Catsmay suffer from cancer of the sweat glands

Skin Disorders in Cattle

These include squamous-cell carcinoma (which

may also affect the eye), iodism, persistent

BVD infection, vitamin E deficiency, vitamin

A deficiency, papillomatosis, lice infestation,

ringworm and the effect of a snake-bite

Skin Grafting Transplantation

The pedicle technique, in which the transplant

is attached at one end to adjacent skin, has been

applied in cats and dogs A broad flap of skin is

formed by incision to cover the denuded area,

with a narrow strip to form the pedicle or

bridge to carry the blood supply to the broad

flap or graft The edges of the pedicle are

sutured; the flap is sutured to adjacent skin

In horses, skin grafting has also been carried

out using free, whole-thickness grafts of skin

taken from other sites in the same animal Such

grafts will give rise to normal hair growth

In a cat a badly damaged tail was used as a

source of skin for a graft before tail amputation

– extensive skin loss having resulted from a

fan-belt accident

Skin, Poisoning Through

(see under POISONING;HYPERKERATOSIS)

‘Skin Tuberculosis’

This is characterised by the appearance of

swellings, varying in size from that of a pea to

that of a tangerine, on the limbs and

occasion-ally on the trunk of cattle Lesions are often

mul-tiple and in the form of a chain, often along the

lines of the lymphatic vessels They are unsightly

but appear to cause the cow no discomfort and

their economic importance lies only in the fact

that they apparently sensitise the animal to

mam-malian and/or avian tuberculin, thus

complicat-ing the interpretation of the tuberculin test This,

indeed, may give rise to anxiety on the part of the

owners of attested herds A re-test after an

inter-val of 30 to 60 days will, however, in the absence

of tuberculosis, usually give a reaction justifying

retention of the animal within the herd

Microscopically, the lesions of ‘skin

tubercu-losis’ closely resemble those of tuberculosis, and

acid-fast bacilli resembling Mycobacterium

tuberculosis are present in them.

Skull

The bony structure of the head Excavated in itthere are large irregular spaces known as sinuses.(See SINUSES OF SKULL.)

General arrangement of the skullTheskull is divided into 2 parts: (1) the cranium;and (2) the face The former consists of the posterior part, which encloses the brain.Most of the bones of the skull are flat bonesdeveloped from a structure which is partly car-tilage and partly fibrous membrane Centres ofossification appear in these during early life,and soon after birth the greater part of eachbone has assumed its eventual outline, but isseparated from its neighbours by an intimatelydovetailed joint These joints, none of which ismovable, allow growth until the animal is adult,when bony fusion usually occurs, and the jointsbecome obliterated Many of these joints –

‘sutures’, as they are called – can be felt in theskull of a newly born animal, particularly overthe dome of the head in a foal or puppy, and for

a time constitute especially vulnerable parts ofthe skull

The bones of the cranium – those whichenclose the brain and its membranes – are 10 innumber: 4 single and 3 paired They are occip-ital, sphenoid, ethmoid, interparietal (single),and parietals, frontals, and temporals (paired).The occipital lies at the posterior lower aspect

of the skull, and forms the hinder wall of thebrain cavity Through it passes the spinal cord,which emerges by the foramen magnum, and to

a roughened prominence above this foramen isattached the very powerful ‘ligamentumnuchae’, which supports the head On eitherside of the foramen are the occipital condyleswhich articulate with the atlas – the first of the cervical vertebrae The lower part of the

occipital – the basilarpart – runs forward along

the base of the brain to meet the body of the

646 Skin Disorders in Cattle

S

sphenoid bone The inner surface is adapted to

the cerebellum – the most posterior upper part

of the brain, while above the basilar portion lies

the medulla which is continued backwards into

the spinal cord It has the form of a body with

2 pairs of wings and 1 pair of projections It is

supposed to resemble a bird with 2 pairs of

wings in flight trailing its legs behind it The

body is continuous with the basilar part of

the occipital, and helps to form the base of the

brain

Skunks

Skunks and foxes are now the 2 most important

wildlife hosts of the rabies virus in the USA

Slag

(see BASIC SLAG)

Slatted Floors

These were tried in England in the 19th

centu-ry and described in the RASE Journal of 1860,

and had been used for many years in Norway,

before being re-introduced in Britain as a

means of saving money on straw The current

practice is sometimes to sprinkle sawdust on the

slats (of wood or concrete), but to use no straw

The use of slatted floors can hardly be regarded

as anything but a retrograde step from the

animal husbandry point of view, however

attractive commercially The animals obviously

cannot rest as comfortably as on straw, and if

strict precautions are not taken (as in Norway)

they may be subjected to severe draughts with

resultant ill-health and poor food conversion

ratios Teat and leg injuries, and injuries or

abnormalities of the feet, may also develop in

animals on slats (See also EPIPHYSITIS.)

The space between the slats is critical, and

there must be no sharp edges on the concrete

(See LAMENESS.)

A slatted dunging area and a bedded area

are satisfactory (See also under SOW STALLS and

SLURRY.)

Slaughter

(see under EUTHANASIA; STUNNING) Specified

intervals between cessation of treatment of food

animals with certain drugs are required before

slaughter (See IVERMECTIN.)

Sleep (Horses)

The rest obtained by horses sleeping in an erect

position is, actually, not sufficient for their

needs They require complete relaxation of their

muscles, and this can only be furnished in the

recumbent position When from fear, ankylosis

of vertebrae, or other cause a horse does not lie

down, it should be placed in slings, or givensome form of support, such as a rope betweenthe heel posts upon which the hindquartersmay bear, so that it may obtain the requisiterest

On board ship, and for surgical or other sons, horses may be kept standing withoutharm for considerable periods, but they should

rea-be exercised for a short while 2 or 3 times daily,

in order that the muscles may be preventedfrom becoming stiff Horses are liable to fallwhile standing asleep, and may, in rare cases,actually come to the ground through the relax-ation of their extensor muscles; what happensmore frequently is that they knuckle over on totheir fetlocks, recovering themselves almost atonce, but not before a slight injury has beeninflicted to the skin over the joint The fallalways occurs in front, not behind, probablybecause of the extra weight carried by the fore-legs

‘Sleeper’ Syndrome (Haemophilosis)

This takes the form of a septicaemia, is caused

by Haemophilus somnus, and occurs in cattle in

feedlots in the USA The syndrome is

associat-ed with an encephalomyelitis; as well as brainand spinal cord, many other tissues may beinvolved It has also been seen in the UK

Sleeping Sickness

Human trypanosomiasis transmitted by tsetse

flies and caused by Trypanosoma gambiense and

T rhodesiensis (See TRYPANOSOMES;TROPICS;

FLIES.) Sleeping sickness caused by T

rhodesien-sis can also be transmitted from person to

person

‘Sleepy Foal Disease’

Infection with one of the Gram-negative bacteria (see under FOALS,DISEASES OF)

Slings

A device whereby a large animal may be kept inthe standing position for long periods withoutbecoming completely exhausted The apparatusconsists essentially of a broad strong sheetwhich passes under the animal’s chest andabdomen, supported by a block-and-tackle orother means to a beam overhead Connectedwith this there are 2 strong straps, one passinground the front of the chest, and the other pass-ing round the buttocks These latter serve tohold the sling in position, and prevent the animals from struggling free The whole isadjustable so that it may fit animals of differentsizes The sling is often made with a metal or

Slings 647

S

wooden bar along each end of the sheet; these

bars serve to distribute the weight of the animal

along the whole width of the sheet, and afford

a rigid means of attachment to the cross-beam

of the slings, to which the chain or rope of the

block-and-tackle is attached

In addition to the above use, slings are one

of the means of lifting a horse that has either

fallen or lain down in a stable and is unable to

rise The horse is placed so that the slings may

be pulled under it, or is rolled on to them,

and after the chest and breeching straps

are arranged, the horse is lifted by the

block-and-tackle high enough to be able to use its

feet It sometimes happens that if the horse has

lain for a considerable time it refuses to support

its weight on its feet, but hangs ‘like a herring’

in the slings In such cases it may be necessary

to startle the horse, when it will generally make

a lunge and ‘find its feet’

Slings are employed in a variety of conditions,

e.g fractures

When slings are applied to an animal, they

should not be fixed up so tightly that the

animal is unable to walk a step or so in each

direction They are only required as a means of

support for the animal when it so desires, and

not as a suspensory apparatus which is always in

use The animal soon learns to lean on the

slings and rest its feet The hand should be able

to be passed under the sling webbing when the

animal is standing immediately under the

cen-tre of the block-and-tackle, and neither the

chest strap nor the breeching should be buckled

up tightly It is generally necessary to secure the

head of the animal by a halter to restrict its

movements, and to supply a suitable manger or

other receptacle from which it may feed easily

(See also ‘DOWNER COW’ SYNDROME for a

means of lifting a cow.)

Slink Calves

Immature or unborn calves improperly used for

human food The flesh of slink calves is often

called slink veal

‘Slipped’

A colloquial expression meaning aborted; also

dislocated (seebelow)

‘Slipped Shoulder’

(see DISLOCATION and SUPRASCAPULAR

PARAL-YSIS)

Slipped Stifle

Slipped stifle is the popular term for dislocation

of the patella It may be partial, when the

patel-la slides in and out of the trochlear depression

on the femur with each step; or it may be plete, when the patella becomes fixed above theouter lip of the pulley-like trochlear surface,causing all the joints of the affected leg tobecome straightened, and the limb to be heldpointing behind Dislocation of the patella is acommon condition in the dog

Slope Culture

A method of growing micro-organisms on solidmedia (e.g agar) in tubes which are usuallyarranged in racks at the correct angle for theagar to solidify on cooling

Slough

Slough means a dead part separated by naturalprocesses from the rest of the living body Theslough may be only a small part, such as a piece

of skin that has been burnt by heat or chemicals,

or it may be a whole foot (See GANGRENE.)

Slow-Milking Cows

(see under MILKING MACHINES)

Slow Reacting Substances (SRS)

Also called leukotrienes, they are substancesreleased in an anaphylactic reaction whichinduce prolonged smooth-muscle contraction.The effect is seen in asthma

Slugs

The common field slug Agriolimax meticulatus

is of veterinary interest as intermediate host of

the sheep lungworm Cystocaulus ocreatus (For

the danger of slug poisons, see METALDEHYDE.)

Slurry

Slurry is the liquid mixture of urine and faeces,together very often with washing-down waterand rain-water, which has to be disposed offrom pig, beef and dairy units Deaths of pigshave been reported following agitation of slurryduring the emptying of tanks or pits under thepiggery slats It is recommended that slurryshould never be allowed to come within 45 cm(18 in) of the slats, and that especially in hotweather emptying should be carried out at least

648 Slink Calves

S

every 3 or 4 weeks Methane, hydrogen

sul-phide, ammonia, and carbon dioxide may all be

given off as the result of bacterial action on

slurry, giving rise to a mixture both lethal and

explosive

Cows, too, have been overcome by slurry gas

For methods of slurry disposal, see DAIRY

HERD MANAGEMENT (See also under

SALMONEL-LOSIS;PASTURE CONTAMINATION OF;‘MILKSPOT

LIVER’;SILAGE.)

Smear Preparations

A film of blood, pus, etc., smeared on to a

slide, fixed – and if necessary stained – for

microscopical examination

Smedi

An acronym for stillbirth, mummification,

embryonic death, infertility in pigs – a

syn-drome caused by infection with subgroups of

enteroviruses A, B, or C

Smegma

Sebum with a distinctive odour found in the

region of the clitoris and penis For a test using

smegma, see EQUINE CONTAGIOUS METRITIS

Smell

Smell is detected by the dissolving of minute

particles of oderiferous substances, gaseous or

solid, in the mucus lining the nose This

trig-gers a response in the hair-like processes

attached to the nerve cells which is transmitted

to the brain by the olfactory nerve The sense

of smell is much more highly developed in

dogs and cats than in humans They have a

for-mation at the roof of the nasal passage (the

subethmoidal shelf ) that extends the range and

accuracy of smell detection The act of

‘sniff-ing’, familiar in the case of the dog especially,

simply ensures that the particles are rapidly and

forcibly drawn upwards into the nose Smells

may be air-borne or ground smells, those left on

solid objects by an animal, person or object

The response to a smell can differ in different

animals: thus the smell of fish, blood, and offal

has a remarkably stimulating effect upon the

carnivorous animals, while grass, grain, and

vegetable substances stimulate the sense organs

of herbivorous creatures particularly The odour

of flesh, blood, etc., is repulsive to the

herbivo-ra, and may cause great nervousness and fright

Most of the wild grass-eating animals have

remarkably well-developed powers of smell, and

are able to locate their enemies at great

dis-tances – over 1 kilometre – but they also detect

ground smells which are important in marking

out territory It is through the sense of smell

that the male is attracted to the female duringthe season or oestrus of the latter; the odour atthis period is most persistent, and can be appre-ciated at great distances Females recognise theiroffspring by their sense of smell, and damswhose young have died can often be deceivedand persuaded into accepting other young ani-mals by clothing these in the skins of the deadones This fact is made use of in the case of eweswhich have lost their lambs (See JACOBSON’S ORGAN;PHEROMONE.)

Smells as Evidence of Disease

In certain cases the presence of a smell

connect-ed with an animal is almost a diagnostic feature

of disease Thus in decay of the teeth or position of bone there is a characteristic smellwhich, when once it is appreciated, can never

decom-be forgotten, although it is difficult to descridecom-be.The breath, urine, and the milk of a cow suf-fering from acetonaemia have a characteristicsweetish sickly smell Poisoning by certaindrugs, e.g carbolic acid, can be diagnosed tosome extent by the smell of the drug that is left in the mouth or on the skin The urine ofthe horse has the smell of violets after theadministration of turpentine in large quantities

It has been suggested that dogs might betrained to recognise certain smells associatedwith human diseases, and so aid diagnosis at anearly stage

Smog

This is the popular name for fog containing adangerously high proportion of sulphur dioxideand other harmful gases derived from coal firesand factory chimneys (See also OZONE for a further description of smog.)

Smooth Collie

This breed, originally a shepherding dog, caninherit, like other collies, collie eye anomaly.Central progressive retinal atrophy is a dominanttrait

Snails

One or two species are of veterinary interest inconnection with LIVER-FLUKESand tapeworms

The giant African snail (Achatina fulica) is

commonly kept in UK schools to show to ogy class pupils; however, it is a potential human

biol-health risk Third-stage larvae of Angiostrongylus

cantonensis, passed out in rats’ faeces, are

infec-tive for mammals, and in the Far East havecaused meningitis in people; though the major-ity of cases have occurred through eatinguncooked snails Snails are farmed for food inBritain, as well as in France and elsewhere

Snails 649

S

Limbless reptiles, widely distributed and

differ-ing greatly in size Many are poisonous Broadly

speaking, those which have 2 rows of small,

solid, equal-sized teeth on either side of the

upper jaw are non-venomous; while those with

1 row of small teeth on either side of the upper

jaw, and 2 or more large, curved, hollow or

grooved fangs on the outside of the smaller

teeth, should be considered venomous

SignsTwo kinds of symptoms are produced,

depending upon the kind of venomous snake

involved In those of the cobra type there is a

period of excitement immediately after the bite,

lasting only for a few minutes and followed by

a period of normality Then nervous excitement

appears, convulsive seizures follow, and death

takes place from asphyxia If death does not

occur at once, dullness and depression are seen

and death or recovery takes place some hours

later There is usually little pain at the site of

injury, and practically no local reaction in

rapidly fatal cases

The symptoms of bite by the adder (Vipera

berus) – the only poisonous snake found in

Britain – are similar, except that there is local

pain and considerable swelling The skin

becomes a livid colour, tumefied, and if in a

limb there may be severe lameness The dog

often appears to be frightened

With most snakes, the venom is, of course,

introduced by their fangs, which have either a

groove on the surface, as in cobras, or a canal

down its centre, as in adders

The African Ring-hals, however, squirts its

venom with uncanny accuracy for a distance of

about 2 m (6 ft) into the eyes of its victim; the

snake rising and opening its mouth wide, its

head thrown back

The rattlesnake venom contains compounds

possessing zinc, plus an enzyme which causes

destruction of muscle tissue

In Australia, snake bite was diagnosed at

the University of Melbourne in 41 cats over a

6-year period – the tiger snake having been

pos-itively identified in 7 of these cases Symptoms

included weakness, dilated pupils and absence

of normal reaction to light by the pupils, with

vomiting and laboured breathing in some

instances Paralysis and a subnormal

tempera-ture suggest a fatal outcome A high rate of

recovery followed the use of 3000 units of tiger

snake antivenin

Animals susceptibleDogs are the animals

most frequently killed by snake-bites, both at

home and abroad, and sporting dogs suffer

more than others Sheep, cattle, and horsescome next in frequency, whilst cats and pigs are only very rarely killed The reasons for this appear to be that hunting dogs most oftendisturb snakes, and that grazing herbivorousanimals, moving only slowly over a tract ofcountry, disturb snakes less; while the cat is not often attacked because of its greater cautionwhen hunting, and because of its superior agility Pigs apparently are least often killedbecause of the protection they possess in a hardtough skin, with a padding of fat immediatelybelow it

Sneezing

Sneezing is a sudden expulsion of air throughthe nostrils, designed to expel irritating materi-als from the upper air passages; the vocal cordsbeing kept shut till the pressure in the lungs ishigh, and then suddenly released, so that thecontained air is driven through the throat intothe nose Entrance to the mouth is prevented

by the soft palate closing the exit from themouth

Sneezing is induced by the presence in thenose of particles of irritating substances, such

as pungent odours, smoke, dust, spores of tain species of fungi, pollen from some grasses,etc It is also the forerunner of chills, colds,influenza, etc., when it is usually accompanied

cer-by a running at the nostrils, and it is a sign

of the presence of certain parasites, such as

Oestrus larvae in sheep and horses, and rarely Linguatula in dogs In pigs, sneezing is an

important sign of atrophic rhinitis andAujeszky’s disease

‘Snow Blindness’ in Sheep

(see under EYE,DISEASES OF– Keratitis)

Soapwort Poisoning

Soapwort poisoning may occur when the

soapwort plant (Saponaria officinalis) grows

abundantly in pasture The plant contains theglycoside saponin, which causes frothinesswhen stirred in water When saponin is intro-duced into the body it causes dissolution of thered blood cells, stupefaction, paralysis, vomit-ing, and purging with the passage of largeamounts of frothy faeces, which are mixed withblood

650 Snakes

S

A breed of small brown sheep, named after the

isle of Soay in the Outer Hebrides, where they

have existed since before the Roman occupation

of Britain Their fleeces, which weigh 1 or 2 kg

each, are much favoured by hand spinners The

ewes produce only single lambs but mother

them very well The breed has found favour in

Cornwall, where they do not graze clover in a

grass/clover mixture, so that the hillsides are

never overgrazed

Social Behaviour

(see BUNT ORDER)

Sodium (Na)

A metal, the salts of which are white, crystalline,

and very soluble in water Common salt, or

sodium chloride, is contained in the fluids of the

body under natural circumstances, and therefore

the salts of sodium, when used as drugs, act not

through their metallic base but according to

the acid radicle with which the sodium is

com-bined Generally speaking, the salts of sodium

act in a manner very like corresponding salts of

POTASSIUMbut are better tolerated

Sodium carbonate (washing soda) is an

irri-tant internally, and is therefore never given by

the mouth except, in an emergency, as an

emet-ic for the dog A solution of sodium chloride

0.9 per cent is called ‘normal saline’, as it is

isotonic with body fluids

Sodium Arsanilate

Sodium arsanilate is an organic preparation of

arsenic used for the treatment of coccidiosis

in poultry It has been used by intramuscular

and intravenous injection for treatment of

certain diseases caused by the presence of

trypanosomes in the blood

Sodium Deficiency

This may occur in dairy cattle in the UK

in July (See also SALT – Salt licks; METABOLIC

PROFILE TESTS,‘LICKING SYNDROME’.)

Sodium Metabolism

Sodium is important in maintaining osmotic

pressure in the body fluid outside cells, and so

controlling body fluid volume (See also KIDNEYS

– Function, and ALDOSTERONE.)

Sodium Monofluoroacetate

A rodenticide also known as ‘1080’ If ingested

by dogs, symptoms of poisoning include

yelp-ing, sometimes vomityelp-ing, and convulsions This

compound was sometimes used in wild-life

rabies control operations against foxes, etc

to 4000 sq m (1 acre), the daily intake of soilper head could be as much as 370 g (13 oz) inthe rainy season

In Britain, it has been suggested, July derstorms over first-year leys may – by a combination of splashing by rain and poaching

thun-by feet – produce a herbage that is seriouslycontaminated with soil This could well irritatethe sensitive lining of the gut in young lambs,with consequent scouring; this is often seenamong lambs believed to be reasonably freefrom parasitic worms (See also SAND, COLIC;

difficul-or by one approaching the end of a lactation, isparticularly undesirable

Maintaining the S-N-F percentage at a factory level is a more difficult problem for themilk producer than rectifying variations in thebutterfat percentage The causes of S-N-F defi-ciency are not always apparent, and attempts atremedying them may have no rapid effect.Factors involved include breed of cow, herinherited capacity, age, stage of lactation, theseason of the year, feeding, management, andattacks of mastitis

satis-The diet should contain adequate fibre aswell as protein There is some evidence suggest-ing that an all-silage diet may lower S-N-F,unless the silage is of the highest quality

Solids-not-Fat (S-N-F) 651

S

Hay, as well, is desirable (See RATIONS FOR

LIVESTOCK– Winter rationing.)

The percentage of solids-not-fat is relatively

high in October and November, after which

time it begins to decline and falls to a minimum

in February and March It then starts an

upward trend, reaches a high level in May, and

may drop again in July and August

Milk from cows of the Jersey and Guernsey

breeds is relatively high in solids-not-fat British

Friesians, as a rule, give milk low in S-N-F

Inherited capacity is important

The percentage of solids-not-fat in milk varies

according to the stage in the lactation It is high

at the beginning, but falls rapidly to a low level

within 6 to 8 weeks after calving Thereafter, it

rises gradually if the cow is pregnant, while it

tends to decline further if she is not again in calf

Towards the end of the lactation, when the cow

is drying off, it may fall very low

Somatic

Somatic means all the cells belonging to the

body except the germ cells in the gonads

Somatic Nerves

Sensory or motor nerves of the somatic division

of the central nervous system; they deal with

awareness of sensation and with voluntary

control of muscles (See CENTRAL NERVOUS

SYSTEM.)

Somatostatin

A peptide hormone, produced by the

hypothal-amus at the base of the brain, which acts as a

brake on growth by regulating release of growth

hormone directly responsible for tissue growth

Animals immunised against somatostatin are

not subject to this ‘braking’ effect, and it

has been suggested that this technique might

be more effective than conventional growth

promoters used in meat production

Somatotrophin

A growth hormone, produced by the pituitary

gland, which stimulates growth of all body

tissues, and influences mammary-gland

devel-opment Like insulin, somatotrophin helps to

maintain correct glucose levels in the blood

In the 1930s the National Institute for

Research in Dairying found that the hormone

could increase the milk of dairy cows In 1983

research was being directed towards production

of growth hormone by genetic engineering

techniques, with the aim of producing a

com-mercial product which could increase milk

yields This research was successful and trials

showed that in cows, fodder was metabolised

more efficiently, producing higher milk yieldsfor a given quantity of feed However, the argu-ment that this increased efficiency was benefi-cial did not prevail against UK and EU welfareconcerns about its use Although used in theUSA and elsewhere, there is a moratorium onthe use of somatotrophin in the EU (See SOMATOSTATIN;PITUITARY GLAND.)

Sorbitol

A sugar alcohol found in fruits and berries, it isone of the intermediate products in the conver-sion of glucose to fructose In severe diabetesmellitus, it is deposited in the lens of the eye

Sorbitol Dehydrogenase (SDA)

A liver enzyme; raised levels indicate liver damage, particularly in horses Also called L-iditoldehydrogenase

Sore Throat

Sore throat is a popular term for laryngitis orpharyngitis, which is often present duringcatarrh, strangles, influenza, etc (See THROAT –

Throat diseases.) A person with an infectedthroat may pass the infection to the udders ofcows being milked, setting up mastitis

grazing pasture containing Sorghum species.

Hindquarter weakness and paralysis of thebladder may result

to discover whether there are any hard or solidforeign bodies present

Sounds

Sounds are made both normally and

abnormal-ly by some of the organs of the body For ple, during the normal heartbeat there can bedistinguished 2 definite sounds The first ofthese, known as the ‘first heart sound’, is a long

exam-booming noise, similar to the syllable lu¯ b,

which is heard when the ventricles are ing and the atrio-ventricular valves are closing,and which is produced by these processes The

contract-652 Somatic

S