Black''''s veterinary dictionary 21st edition - W pdf

Cases of accidental poisoning have occurred, however, in domestic animals; and food conta-minated by rodents’ urine may be dangerous where warfarin is used.. Washing of Animals see BATHS

‘Walkabout Disease’

(see KIMBERLEY HORSE DISEASE)

Wall Eye (Leukoma)

Wall eye (leukoma) is a condition in which

the brown pigment of the iris is lacking, giving

the iris a steely blue appearance In dogs, it

is usually unilateral and is not a problem In

the horse, wall eyes may occur when the greater

part of the face, or that portion around the

eyes, is white The pupil of the eye appears

to be encircled by a ring of bluish or greyish

white, and the expression of the horse’s face is

consequently unusual It is not a serious defect except in tropical countries

Wallabies

Smaller than kangaroos, these native Australian marsupials are a source of human HYDATID DIS-EASEin the southern tablelands of New South Wales Lumpy jaw is a common finding They may sometimes be found as feral animals in parts of England

Warble Fly Order

The Warble Fly Order came into force in 1989 The presence of warble fly lesions in cattle is a

NOTIFIABLE DISEASEin Britain Where a blood test indicates that an infestation may be pre-sent, treatment under the supervision of an offi-cer of the State Veterinary Service is required Every herd and every bovine animal within

3 km of an infestation must be treated (the fly

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is able to travel only short distances) As warble

flies are present in other countries, all cattle

imported into Britain must be treated for

possible infestation within 24 hours of arrival

The treatment must be supervised by a State

Veterinary Service officer

Warbles

Warbles are swellings about the size of a marble

or small walnut occurring upon the backs of

cattle in spring and early summer, caused by the

presence in them of the larvae of one of the

warble flies – Hypoderma bovis or H lineata.

These are of very great economic importance

The adults – especially H bovis – cause great

annoyance to stock during the period when

eggs are being laid Not only does this result in

injuries, animals rushing around (‘gadding’) to

avoid the attacks, but the milk yield is reduced,

sometimes by as much as 25 per cent, and

condition is impaired

H lineata in its migration through the body

irritates the gullet; and both species may injure

the spinal cord The warbles on the back are

really so many small abscesses which not only

reduce condition very considerably but may,

when many are present, result in the death of

young animals The accidental crushing of a

number of the larvae in these cavities may cause

the death of the animal from anaphylactic shock

In the carcases there is considerable destruction

of valuable meat around the warbles; ‘butcher’s

jelly’ or ‘licked beef’ is an oedematous, straw-coloured, jelly-like substance, which infiltrates the tissue near the larvae The holes which the larvae produce in the hides reduce their value; heavily infected hides are often useless for leather Warbles are most common in young animals,

in which loss of condition is most serious; but they have been found in small numbers in ani-mals up to 15 years old They are sometimes found in young horses The larvae occasionally enter the spinal canal and produce very serious

lesions Horses are attacked mostly by H bovis

larvae, which affect the area of the saddle chiefly; but brain involvement has been

report-ed in the horse In deer, larvae of the warble fly

H diana are often found.

Methods of control Satisfactory control depends upon artificial interference with the life-cycle (See IVERMECTIN.) A systemic insecti-cide will kill a high percentage of larvae before they complete their migration and penetrate the back

In Britain in 1978, 40 per cent of cattle in England and Wales, and 20 percent in Scotland, were affected with warbles (See FLIES – FLYcontrol measure.)

Autumn is the more effective time for treatment, even though infestation cannot be visually detected then, and cattle-owners in warble-affected areas are advised to treat their herds accordingly

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Dressing against warbles.

Pour-on warblecide compounds include

phosmet and ivermectin Parenteral

prepara-tions of abamectin, doramectin and moxidectin

are also effective

ReindeerIn Canada they are attacked by the

warble fly Edoede magena tarandi Ivermectin

has been used for control

GoatsIvermectin has been used also against

the goat warble Przhevalskiana silenus.

Following the introduction of the Warble Fly

Order 1985, infestation by warbles was virtually

eradicated by 1995

The tropical warble fly of Central

America is Dermatobia hominis, which lays its

eggs on an intermediary vector – fly or

mosqui-to – which it catches for the purpose (See also

under FLIES, and IVERMECTIN.)

Warfarin

An anticoagulant drug used in human

medi-cine; its veterinary use is mainly as a rat poison

It causes death of rats and mice from internal

haemorrhage In the strengths used, 0.005 per

cent and 0.025 per cent, it is considered that

properly prepared baits will not prove

danger-ous to livestock if used with ordinary care

Cases of accidental poisoning have occurred,

however, in domestic animals; and food

conta-minated by rodents’ urine may be dangerous

where warfarin is used

Therapeutically, warfarin is used in the

treatment of navicular disease

Treatment of warfarin poisoning

Vitamin K1(phytomenadione) by intramuscular

injection Blood transfusion may be necessary

Once symptoms have appeared, use of

glu-cose saline, or blood transfusion, is indicated

The poisoned animal must be handled very

gently, or further internal bleeding may occur

(See also NAVICULAR DISEASE.)

Warts (Papillomas)

Warts (papillomas) are small growths which

appear on skin or mucous membrane, and

occur in all farm and domestic animals

Papillomas are benign, but an individual wart

can become malignant (See PAPILLOMA.)

Around the mouth they may interfere with

feeding, and when occurring about the nostrils

they may obstruct the breathing Soft warts in

the oesophagus sometimes make swallowing

difficult, and upon the penis or in the urethra

they may hinder the passage of urine (See also

EYE.)

HorsesThe commonest situations are the skin

of the udder or sheath, the lips and nostrils, the eyelids, outer and inner skin of the ears, the region of the breast, and the insides of the limbs

CattleThe commonest seats of warts are the teats of cows Young cows in winter are fre-quently affected about the skin of the eyelids and along the lower line of the abdomen, but the growths often drop off spontaneously from these positions when the young animals are turned out to grass in the early spring Otherwise warty growths are found as in the horse

Dogs and catsIn the dog especially, less so

in the cat, warts are common Single small warts with a cauliflower-like extremity or with a rounded top are commonly found about the eyelids, lips, ears, paws, etc., as well as upon the general surface of the body They usually grow very slowly and may be present for years with-out causing any pain or inconvenience In other cases warts appear in connection with the gums, tongue, and insides of the cheeks; in these positions they arise in clusters and grow very rapidly Cases such as these are usually accompanied by a great amount of salivation and a fetid discharge from the mouth

Removal Of WartsMultiple warts in cattle have been treated by a variety of chemicals, including injections of lithium antimony tartrate, with varying degrees of success Autogenous and other vaccines have also been used where there is a herd problem, and surgical removal may be resorted to

Washing of Animals

(see BATHS)

Wasp Stings

(see under BITES)

Waste Food

(see BAKERY WASTE; SWILL; CHOCOLATE POISONING)

Wasting

(see ATROPHY)

Water and Watering of Animals

Amounts requiredThe quantity of water needed per day by the various domestic animals depends upon the nature of the food, the cli-mate, the temperature, and the size and the

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activity of the animals themselves When very

dry food is given, such as hay, bran, oats, etc.,

more water is required than when roots or

growing grass is eaten

Drinking water should be freely available to

animals, so that they can drink as and when

they choose (See below under ‘Water supply’.)

Stress may occur in an animal deprived of the

chance to drink sufficient water, and actual

dehydration (which can lead to death) may be

caused Production of milk, etc., will obviously

be adversely affected

With an ad lib water supply, the amount of

water required by various animals under various

conditions is of mainly theoretical interest,

apart from practical aspects of planning

ade-quate supplies of piped water, trough space, etc

Water requirement figures can be taken only as

approximate guidelines, and authorities differ

to some extent

CattleDry cows of the larger breeds require

between 36.5 and 45 litres (8 to 10 gallons)

per day Those in milk need in addition about

5 times as much water as the volume of milk

produced, while for the last 4 months of

preg-nancy, the daily consumption may rise to about

70 litres (approximately 15 gallons)

As the air temperature increases above 10°C

(50°F), the water requirement rises rapidly

Calves require much more water after they

are weaned than before A common mistake is

to ignore this fact, with the result that the calves

receive a check to their growth from which they

may never fully recover

Pigs are highly susceptible to water

depriva-tion (See SALT POISONING.) Approximate

quan-tities required have been given as 4.5 litres

(1 gallon) per day for a litter of 3-week-old

piglets, and up to 22.5 litres (5 gallons) per day

for a nursing sow The benefits of creep feeding

may be lost if the piglets are denied water

Quality of waterThis is obviously of prime

importance Animals may suffer thirst and

stress if the only drinking water available to

them is disagreeable in taste Where piped

water is not available, and rainwater has to be

stored in tanks, it is important to clean out

gut-ters and the tanks themselves Galvanised iron

tanks should not be allowed to get rusty

Well-water may contain an excess of one or more

minerals which may make it unpalatable or be

harmful to the animal, so that sampling and

analysis should be carried out

Poisoning by water may result from the use

of lead pipes or tanks (See LEAD POISONING.)

The use of lead paints in storage tanks is also a danger (See also ZINC POISONING.) Stored rain-water containing decaying organic matter (leaves, bird droppings, etc.) has led to the death of pigs from nitrite poisoning

Diseases spread by water Apart from illness caused by some inorganic substance dissolved in the water, such as lead from lead pipes or tanks, or arsenic from contamination with sheep-dip, water-borne infection may cause disease

Among diseases that can be distributed in this manner are the following: anthrax, from water used in tanneries or wool-washing premises, or when a carcase has been buried near a stream; Johne’s disease, salmonellosis, and coccidiosis in cattle, from contamination of streams, ditches, and ponds Liver fluke can be

spread via infected mud snails, Lymnaea

trun-catula Leptospira hardjo infection is 8 times

more likely where cattle have access to a water course

Washing water and water-tanks have been

contaminated with, for example, Bacillus

subtilis, leading to MASTITIS

Water supplyA good stockman will ensure that the animals in his care are never short of water; that all automatic drinking bowls or nip-ple drinkers are in working order; that frost has not cut off the supply of piped water (lagging of exposed pipes is obviously necessary in winter); and that the water has not been allowed to freeze in troughs, tanks, etc It is also necessary

to ensure that the levers of automatic drinking

Designed for field use, this CemFil glass fibre-reinforced cement drinking trough is obtainable in sizes of up to 2000-litre capacity The water supply

is, of course, piped.

Water and Watering of Animals 771

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bowls are not too stiff for young animals to

operate, and that young stock are shown

work-ing nipple drinkers – not left to find them for

themselves (See also ALGAE.)

In one incident, newly weaned pigs were put

into a yard having automatic water-bowls

fit-ted, but as the yard had been mucked out the

bowls were out of reach of the young pigs

Pigs deprived of water show nervous

symp-toms They may walk in circles, or backwards,

press their heads against a wall, champ their jaws,

collapse and have convulsions Of course, some

pigs may be found dead without symptoms

having been observed

Sheep have shown symptoms suggestive of

twin-lamb disease, and died, after being

removed from a field where they had access to

a stream and placed on pasture where the

ball-valve of a drinking trough had been tied up

Sheep prefer to drink running water, and those

of some breeds are so reluctant to drink

any-thing else that, when housed, a running water

supply must be arranged indoors

A drop in milk yield may occur in dairy

herds where the cows are moved periodically to

a field too far from a water-trough; or where the

water pressure is too low to ensure adequate

supply

Dogs, cats, and poultry should always be

allowed an unlimited supply of water so

arranged that they are unable to foul or upset

the drinking vessels

(See also DEHYDRATION.)

Horses Wherever possible, water should be

given before the food, or not for 1 to 2 hours

after feeding The horse’s stomach is small, and

cannot contain a full feed and several litres/

gallons of water simultaneously Water in excess

of requirements should be offered when horses

are at rest, and they should be allowed to drink

frequently when working

Water intoxication This may occur in

farm livestock when, as a result of bad

manage-ment, they have been deprived of adequate

drinking water and then suddenly find

them-selves in circumstances which enable them to

drink as much as they want

One symptom may be a red discoloration of

the urine Convulsions, recumbency,

hyperaes-thesia, aimless wandering, and death have been

seen in calves

Water Buffaloes

Water buffaloes are regarded by many as an

under-utilised form of livestock It is common

practice in the tropics to immerse them in water

during the heat of the day as they have very few sweat glands and are prone to heatstroke However, they can be reared away from water if shade is available They are widely used as a draught animal in warmer countries, including the poorer parts of Italy They are farmed in Britain to produce mozzarella cheese Studies in the USA, Papua New Guinea, Trinidad and Australia have shown water buffalo perform well as regards growth rates, health and produc-ton of meat and milk They are able to digest rougher material than cattle or sheep

Water buffalo meat is similar in taste to beef; the milk is richer in butterfat and solids-not-fat than cows’ milk There is a general low inci-dence of mastitis, probably because on ceasing milking, the teat canal closes very rapidly Water buffalo are generally quite docile unless severely stressed or in pain

Some of the steps needed to permit greater exploitation of this valuable animal are:

1 Trials to compare growth rate, feeding, nutrition and other characteristics of water buffalo with those of cattle

2 Selective breeding and protection of out-standing buffalo specimens, especially in Southeast Asia

3 Replacement of the 1500-year-old ineffi-cient wooden yoke (in rural Asia, where the water buffalo is the small farmer’s ‘tractor’, improved harnesses could increase pulling power by up to 25 per cent) (See TRANSPORT OF ANIMALS.)

The limitation of water buffaloes must be taken into account For instance, the animals suffer if forced to remain, even for a few hours,

in direct sunlight They cannot be worked for long periods during the heat of the day, and

they are also susceptible to extreme cold (The

Water Buffalo: New Prospects for an Underutilized Animal, US National Academy of

Sciences)

An important roundworm of the water

buf-falo (Bubalus bubalis) is Paracooperia nodulosa.

This causes development of nodules in the intestine, and diarrhoea, anaemia, emaciation and sometimes death (See LIVESTOCK PRODUC-TION.)

Water-Dropwort

This is Oenanthe fistulosa, and while it and pars-ley water-dropwort (O lachenalii and also O.

aquatica) are all poisonous, they are less so than

hemlock water-dropwort (O crocata) – a weed

of marshy places, ditches, and other wet loca-tions This is considered to be one of the most dangerous and poisonous of the commoner plants found in Britain, and many cases of

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poisoning, not only among animals but also

among human beings, have been recorded It is

a member of the same botanical class as

cow-bane, hemlock, and fool’s parsley, and like them

the poisonous principle is found in all parts of

the plant In its leaves it has a great similarity to

celery, and its rootstock has been mistaken for

parsnip The active toxic principle is called

oenanthotoxin, and is most abundant in the

root Hemlock water-dropwort often causes

problems when roots of the plant are exposed

following hedging and ditching, and canal bank

and stream clearances

SignsThe symptoms appear very quickly after

the plant has been eaten, and death follows

within 1 to 4 hours when large amounts have

been taken Cattle become very depressed in

general appearance, and their respiration is fast

and laboured The mucous membranes become

congested, the eye rolls, the pulse is weak and

fast, and there is a certain amount of foaming at

the mouth Convulsions follow

In some cases that are not fatal, one or more

of the limbs may remain paralysed In the horse

the appearance of symptoms and the course of

the illness are much more rapid and the nervous

symptoms are exaggerated

TreatmentBarbiturates may save life

Water-Fleas

Daphnia pulex, a brown water-flea found in

British ponds, is the intermediate host of the

roundworms of ducks, e.g Acuaria uncinata.

Water Hemlock

Water hemlock, a common plant of damp marshy places in all parts of the Northern Hemisphere, has a short, stout hollow root-stock, and large much-divided leaves set on

strong stems Water hemlock (Cicuta virosa) is

also known as cowbane

The root in springtime contains the greatest amount of the poisonous principles, which are

3 in number, viz an alkaloid, cicutine; an oil, oil of cicuta; and a bitter resinous substance, cicutoxin

Signs Salivation, dullness, vomiting in pigs; colic in horses; bloat in cattle; together with diarrhoea, a staggering gait Sudden death or a few hours’ illness

First AidOwing to the rapidity of the appear-ance of symptoms it is not often that treatment

Water-dropwort (Oenanthe crocata) This should

strictly be called hemlock water-dropwort The

roots are the most poisonous part of the plant,

and are often dislodged during severe floods or

ditching or drainage work Height: about 1.3 m (4

ft).

Water hemlock or cowbane (Cicuta virosa),

show-ing the dahlia-like roots attached to the enlarged base of the stem, seed capsule, leaves and green-ish-white inflorescence The flowering stem may be 1.6 to 2.5 m (5 to 10 ft) tall.

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can be successfully carried out Strong black

coffee or tea may be given Veterinary help

should be sought

Water, Loss of

Loss of water from the tissues – a serious

con-dition – is referred to under DEHYDRATION It

occurs especially during the course of diarrhoea

Waterhammer Pulse

The peculiarly sudden pulse that is associated

with incompetence of the aortic valves of the

left side of the heart

Watery Mouth

An often fatal disease of newborn lambs in the

UK E coli is commonly isolated but its

involvement in the disease is unclear The lambs

appear strong and healthy but on taking milk

from the ewe they soon show signs of

abdomi-nal pain, and a watery fluid drips from the

mouth There may be scouring Death soon

follows as a rule

In a summary of the clinical features of

102 cases of watery mouth in lambs, the

majority of cases were observed in ram lambs

(73 per cent) and within the first 3 days of

life (80 per cent) The results suggest that the

incidence of watery mouth may be reduced

by delaying castration until lambs are at least

3 days old A similar condition occurs in calves,

also due to E coli.

WBC

White blood cells

Weals

Weals are raised white areas of the skin which

possess reddened margins They may result

from sharp blows or from continued pressure

against some hard object They are only visible

upon the skins of pigs, as the hair of the other

domestic animals hides the actual skin surface

(See URTICARIA.)

The term ‘weal’ is also used in surgery in

connection with the use of local anaesthetic

solution A primary weal is made, and when

the local anaesthetic has taken effect, the needle

of the syringe may be reintroduced into the

now insensitive area and further injections

made painlessly in order to anaesthetise a given

area

Weaning

Weaning is a critical period in the life of the

young animal unless carried out with care

Generally speaking, it is necessary to accustom

the young growing animal to a diet in which its

dam’s milk takes a more and more secondary place for some weeks before actual separation occurs In the case of dairy cattle there is an exception to this rule, in that newly born calves are often taken away from their mothers as soon

as they have had some colostrum, and are then reared from a pail Sudden changes in the diet are to be avoided at all times, and the changes from a milk to a herbivorous or omnivorous diet should be gradual, for obvious reasons In modern pig husbandry, creep-feeding is prac-tised before weaning (See CREEP-FEEDING;

COLOSTRUM.)

Early weaning of calves Most calves in the dairy herd are taken from their mothers within a day or two of birth, after they have received colostrum They are then introduced

to milk or milk-substitute feeding from a

buck-et, a teated container or an automatic machine feeder The amount of liquid the calf receives with the first 2 methods is restricted, usually, to about 2 litres of milk or substitute containing 12.5 per cent solids This does not completely satisfy the appetite of the growing calf, so it is introduced to roughage, in the form of creep feed and water They continue on a fixed quan-tity of the liquid feed and gradually increase the amount of other feed consumed This allows them to be completely weaned at a younger age than would otherwise be possible Calves can be weaned when they are consuming 0.7 kg (11⁄2 lb) daily if in single pens, or 1 kg (2 lb) on aver-age if in group pens, for 3 consecutive days It has, however, been suggested that calves should not be weaned until they double their birth-weight or are at least 80 kg (175 lb), whichever

is the heavier

Early weaning of pigletsMost piglets are weaned at 3 to 4 weeks Earlier weaning is only permissible if the health and /or welfare of the sow or the litter would be adversely affected by the normal weaning age

Piglets suckled to 8 weeks can cause marked loss of condition in the sow Weaning at 4 weeks allows quicker turnround in the farrowing house, and consequently less accommodation is needed – as well as the attainment of more than

4 litters in 2 years Food-costs per piglet are higher by this method, but weight at 8 weeks can be appreciably higher The sow must be taken from the piglets, not vice versa, and housed out of earshot, as she will fret (See also under SOW’S MILK.)

Early weaning of lambs (see SHEEP BREEDING)

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The particles finer than bran of the husk of

wheat, containing not more than about 6 per

cent crude fibre They are also known as offals

and middlings, and much confusion exists

between these various terms

Weaving

Weaving was thought to be a vice of horses and

a form of stereotypical behaviour, but this is

open to doubt Affected animals swing the head

and neck and the anterior parts of the body

backwards and forwards; sometimes the

affect-ed animal appears not to be able to stand still

on all 4 feet and lifts each foot in turn The

behaviour shown is thought to indicate pain It

has been postulated that the affected horse is

suffering from trigeminal neuralgia, a

recog-nised condition in man that causes excruciating

pain In some cases, a degree of relief has been

obtained by tracheotomy; it appears that the

mere passage of air through the nose is enough

to cause the clinical signs

Wedder (Wether)

A castrated male lamb, after weaning (see under

SHEEP)

Wedge Osteotomy

An operation for treating an angular deformity

of the horse’s fetlock of 8°or more

Weedkillers

Weedkillers used in agriculture include:

DNOC, DNP, PARAQUAT,DIQUAT Hormone

weedkillers: MCPA, Agroxone 4, and 2, 4-D

MCPA, it is claimed, renders pasture more

palatable and has no ill-effects upon cattle or

their milk Ragwort and buttercups also

become more palatable, due to a temporary

increase in their sugar content, and poisoning

may consequently arise (See also HERBICIDES.)

Weights of Cattle

At birth, calves of the larger breeds weigh 36 to

54 kg (80 to 120 lb) – 77 kg (170 lb) has been

recorded The averages for heifer calves are

about: British Friesian, 39 kg (86 lb); Dairy

Shorthorn, 36 kg (80 lb); Jersey, 25 kg (56 lb)

Bull calves weigh about 2.25 kg (5 lb) more

Weights of Horses

At birth, a Shire or Clydesdale foal averages

90 or 100 kg (11⁄2or 2 cwt)

Weights of Pigs

Averages in Britain are as follows: at birth, 0.9 or

1.4 kg (2 or 3 lb); at 3 weeks, 5.4 or 5.9 kg (12

or 13 lb); at 8 weeks, 16 or 16.6 kg (36 or 37 lb)

Weil’s Disease

(see LEPTOSPIROSIS IN DOGS)

Weimaraner

A German breed of dog, medium to large, with long neck, pendulous ears and a smooth silvery coat Originally used as a pointer and retriever Close to extinction at the end of the 1939–45 war, it was saved by British troops Distortion of the nictitating membrane may be found, as well

as spinal dysraphism (an abnormal dilation of the central canal of the spinal cord) Cutaneous asthenia and ununited anconal process may be inherited, as may haemophilia A

Welfare Codes for Animals

Welfare Codes for Animals produced under the Agriculture (Miscellaneous Provisions) Act

1968, make recommendations as to how ani-mals should be kept There are codes covering cattle, domestic fowl, ducks, farmed deer, goats, pigs, rabbits, sheep and turkeys Anyone keep-ing any of those species must have, and have read, a copy of the appropriate code; staff looking after the animals must also have read

it While the codes are advisory only (but see

below), if the recommendations are ignored and animals suffer in consequence, the code can

be used in evidence in a court of law

RegulationsThe regulations relating to cat-tle, poultry, pigs and rabbits (Welfare of Farmed Animal Regulations 2000) have converted some of the recommendations of the codes

of practice into mandatory requirements (e.g stocking densities for pigs) The regulations also prevent the routine tail-docking and tooth-clipping of pigs except where this is necessary (a case for performing such operations must be made) Tail-docking of cattle, surgical castra-tion of poultry and interference with the vision

of birds are also prohibited (see also under FARM ANIMAL WELFARE COUNCIL;LAW)

Welfare of Animals at Slaughter Act

This amends the Acts of 1974 and 1980, and covers the formal training, examination, and licensing of slaughtermen, codes of practice relating to welfare, in both slaughterhouses and knackers’ yards

Welfare of Farmed Animal Regulations 2000

Welfare of Farmed Animal Regulations 2000 specify the minimum standards under which farmed animals are to be kept There are special provisions for battery hens, calves, pigs and

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rabbits The regulations incorporate many of the

guidelines in the WELFARE CODES FOR ANIMALS

Wells (Well Water)

(see WATER AND WATERING OF ANIMALS)

Welfare of Animals (Slaughter

or Killing) Regulations 1995

These cover the licensing of slaughtermen and

knackermen, including the handling of animals

at abattoirs They detail the (only) methods by

which animals may be slaughtered or killed

Wesselsbron Disease

Cause A flavivirus Transmitted by

mosqui-toes, and communicable to man, this infection

was first reported in South Africa in 1955 It

caused death of lambs, abortion, and some

deaths of ewes; persistent muscular pain in

man It resembles Rift Valley fever

West Highland White Terrier

A small, rough-haired breed, with pointed ears

and black nose The breed is prone to

cran-iomandibular osteopathy, inguinal hernia,

keratoconjunctivitis sicca and Perthe’s disease

West Nile Virus

Cause of an infection, mainly in wild birds;

corvids (crows, magpies, jays) are particularly

susceptible, with dead birds literally falling out of

the sky The disease was transported from Israel

to the USA in 1998 and spread rapidly, reaching

Canada Virus is transmitted by mosquitoes;

humans and other primates can be infected, but

a mosquito biting an infected human is unable

to transmit the disease to another person There

is evidence that the infection is present in British

wild birds The virus is related to yellow fever

and Japanese encephalitis viruses

Wether

A castrated male sheep after weaning (see under

SHEEP)

Wetting Agents

Substances which lower the surface tension of

water, so that the latter spreads out over the

surface rather than remaining in the form of

drops Good wetting ability is a characteristic of

detergents, which play an essential part in the

disinfection of vessels, pipes, glassware used for

milking equipment, etc

Wharton’s Duct

Wharton’s duct is the name of the tube by

which saliva secreted by the submaxillary gland

reaches the cavity of the mouth It opens in the floor of the mouth almost opposite to the canine tooth in the horse

Wharton’s Jelly

Wharton’s jelly is the embryonic connective tissue that forms the basis of the umbilical cord

in the fetus In its substance are found the umbilical vessels and the other structures that constitute the umbilical cord

Wheat Gluten

For the adverse effect of this in some instances

in calves, see under SOYA BEANS

Wheezing

(see BRONCHITIS; also‘BROKEN WIND’)

Whelping

(see under PARTURITION, in the bitch)

Whey

Whey is the liquid residue left after the separa-tion of the curds in cheesemaking Used as a food, particularly for pigs Can be a source of infection if made from unpasteurised milk

Whippet

A medium-sized dog of the greyhound type The breed is prone to alopecia

Whipworm

Whipworm is the popular name for the Trichuris found in the caecum (See ROUND-WORMS.)

Whirling Disease

A parasitic disease of fish caused by the

proto-zoan Myxosoma cerebralis The parasite spends

part of its life-cycle in mud; after swallowing

by the fish it migrates and penetrates the carti-lage of the skull Affected fish swim erratically There is no treatment but the disease can be prevented by rearing young fish in plastic or concrete-lined ponds until the skull is ossified – the parasite cannot penetrate bone It was formerly a notifiable disease

Whistling

Whistling is a defect affecting the respir-atory system of the horse In many respects

it is similar to ‘ROARING’, but the note emit-ted is higher pitched It constitutes an unsoundness

White Cells

(see under BLOOD For white cells in milk, see under MASTITIS)

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White Diarrhoea, Bacillary

(see under PULLORUM DISEASE)

‘White Heifer Disease’

The name given to defects in the genitalia most

commonly found in Shorthorn cattle The

defects can vary from the presence of fibrous

tissue across the posterior part of the vagina

(‘persistent hymen’) that may be corrected

surgically, to the absence of all or part of the

uterus

White Line

White line is the margin of horn that runs

round the outside of the sole, between it and

the wall, in the horse’s hoof It acts as a slightly

pliable cementing material between wall and

sole It is important as a guide to the shoeing

smith, since it forms a line inside which it is

unsafe to drive a nail without risk of pricking

the sensitive parts of the foot

White Muscle Disease

White muscle disease is another name for the

result of vitamin E deficiency (See MUSCLES,

DISEASES OF– Nutritional myopathy.)

White Scour in Calves

White scour in calves is a disease affecting calves

within the first 3 weeks of life The

disease is usually a rapid one In the acute case

the calf may be found dead or dying; in other

cases death occurs within 3 to 10 days after

symptoms are first noticed

Causeis usually E coli, but other organisms

may be involved, including Proteus vulgaris

andPseudomonas pyocyanea, Salmonella spp.

Predisposing causes include: exposure to cold

and damp; deprivation of colostrum; sudden

changes in diet; feeding with unsound milk

or mouldy calf-meals from unclean utensils; overcrowding; and housing healthy calves in pens or boxes that have previously contained cases of the disease and have not been carefully disinfected afterwards

White scour is very rare in beef cattle at pasture

Calving-boxes should be disinfected and well littered before the pregnant cattle occupy them

A protective serum has been used with encour-aging results Where bucket-feeding is adopted, colostrum must not be withheld

Treatment It is essential to overcome the dehydration resulting from the diarrhoea (For details, see DEHYDRATION.)

Other treatment comprises the use of E coli

antiserum, sulfamezathine or one of the other sulfa drugs, and in some cases the inclusion of yeast in the diet Serum from the dam has been given by subcutaneous injection in default of colostrum (See also DIARRHOEA.)

White Spot

White spot is a parasitic disease in which white cysts are formed all over the surface of the fish, including the gills It is more common in the carp family, including goldfish The cause is

Icthyophthirius multifiliis Part of its life-cycle

is spent at the bottom of ponds, from where the infective stage is released into the water and makes for the fish It is only at this stage that the parasite can be treated Zinc-free malachite green is used to create a very dilute solution

in the pond (0.1 ppm), as the parasite will continue to be released until eradicated Treatment instructions must be followed carefully if toxicity is to be avoided

‘Whites’

‘Whites’ is another name for leukorrhoea, and

is a term popularly used in connection with

C pyogenes infection in cows (See LEUKOR-RHOEA;UTERUS,DISEASES OF;VAGINITIS.)

Whiteside Test

This has been used for the detection of subclin-ical mastitis, by indicating an abnormally high white-cell count of the milk A modified ver-sion consists of placing 1 drop of 4 per cent caustic soda (NaOH) and 5 drops of the milk

on a glass plate, and stirring with a glass rod for

20 seconds or so The presence of flakes indi-cates a positive result; a viscous mass at the end

of the rod suggests a strong positive result It is

a laboratory version of the California Mastitis Test

An arched back is characteristic of white scour;

also a dejected appearance.

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