Black''''s veterinary dictionary 21st edition - R doc

In Asia and South America dogs are still the most important vectors, but in many countries wild animals provide a reservoir of infection, and infect dogs and cats and farm animals – whic

R Factor

(see PLASMIDS)

Rabbit Fur Mite

This may be picked up by dogs and

rabbit-keepers, and cause intense irritation (See

CHEYLETIELLA PARASITIVORAX.)

Rabbit Haemorrhagic Disease

Rabbit haemorrhagic disease is widespread

throughout the UK and the rest of Europe

The disease, caused by a calicivirus, originated in

China and may have been imported into Europe

in rabbit meat Cases are not known in rabbits

under 4 months, at which age liver metabolism

changes This makes it a serious problem for

breeders when a doe dies, leaving an orphan

litter Clinical signs are often transient: difficulty

in breathing, or a short squeal followed

immedi-ately by the rabbit falling over, is often

accom-panied by sudden death Animals surviving the

acute stage develop jaundice and die after a few

weeks Haemorrhage from the nostrils and/or

anus may be seen Prevention is by vaccination

Rabbit Rings

The British Rabbit Council issues 100,000

metal rings each year in the UK to members to

use in identifying rabbits, but advises that the

rings should be removed from rabbits sold or

given away as pets ‘Injury can occur if bedding

material becomes trapped between ring and

leg,’ or if the ring has become – with the

rabbit’s growth – too tight, with the risk of

causing necrosis Should that occur, surgical

intervention or euthanasia will be needed

‘Rabbit Syphilis’

‘Rabbit syphilis’ is caused by a spirochaete,

Treponema cuniculi (which does not affect

humans) It is a venereal disease characterised

by the appearance of nodules and superficial

ulcers covered with thin, moist, scaly crusts

and oedematous swellings of the surrounding

tissues mainly in the region of the genitalia

(hence the colloquial name, ‘vent disease’) and

also sometimes in the region of the nose

Rabbits

Breeds of domesticated rabbits used for table

purposes include the New Zealand white, the

California, and the Dutch rabbit (See also PETS,

CHILDREN‘S AND EXOTIC.)

HandlingWhen lifting a rabbit, a fold of skinover the shoulder and back should be graspedwith one hand, while the other supports therump A rabbit should not be lifted by its ears.Struggling while being inexpertly handled canlead to fractures of limbs A startled rabbit mayleap and fracture the spine

Diseases include APPENDICITIS; ATROPHIC RHINITIS; COCCIDIOSIS; HYDROMETRA (theaccumulation of watery fluid in the uterus);

IMPACTIONof colon or stomach (often the result

of insufficient hay being provided); LISTERIOSIS;

MASTITIS;METRITIS;MYXOMATOSIS; LOSIS; PNEUMONIA; RABBIT HAEMORRHAGIC DISEASE; ‘RABBIT SYPHILIS’; SALMONELLOSIS;

PASTEUREL-SCHMORL’S DISEASE;TOXOPLASMOSIS; LOSIS;TYZZER’S DISEASE;YERSINIOSIS

TUBERCU-Pasteurella multocida causes a pneumonia

which may be acute and fatal in rabbits under

12 weeks old It may cause also middle-ear ease with a loss of balance, circling, and headheld to one side, epiphora, and also ‘snuffles’ inwhich there is a discharge from eyes and noseand sneezing

dis-Rabbits act as hosts of the liver-fluke of sheep,and of the cystic stages of some tape-worms, e.g

Taenia pisiformis, T serialis.

Rabbits have been used experimentally asincubators for sheep’s eggs

A hermaphrodite rabbit served severalfemales and sired more than 250 young of bothsexes In the next breeding season the rabbit,which was housed in isolation, became pregnantand delivered 7 healthy young of both sexes

Pregnancy diagnosis An ELISA test isavailable for this purpose It can also differenti-ate between pseudo-pregnancy and pregnancy,and detect rabbits about to ovulate

AnaesthesiaA wide range of anaesthetics issuitable for use in rabbits Halothane and otherinhalation anaesthetics are suitable and conve-nient to administer Premedication withatropine (50 micrograms per kg by hypodermic

or intramuscular injection) or acepromazine (1 mg per kg intramuscularly) is advisable half

an hour earlier Alfaxalone/alfadolone (Saffan)

is one of several injectable anaesthetics mended for surgery Oxygen should be ready

recom-to hand

The Veterinary Formulary, published by

the BVA/Royal Pharmaceutical Society, gives

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comprehensive details of anaesthetics and

analgesics suitable for rabbits and small rodents

Rabies

The Latin word for madness, it is a specific

inoc-ulable contagious disease of virtually all

mam-mals, including man; and occasionally it occurs

in birds, e.g domestic poultry and vultures It is

characterised by nervous derangement, often by a

change in temperament, with paralysis occurring

in the final – and sometimes in the intermediate

– stages

Foxes and cattle are both highly susceptible

to infection

Rabies occurs in all continents with the

exception of Australasia and Antarctica In

Turkey, dogs remain the principal vectors; in a

few countries in Europe cats attack more people

than do dogs In Asia and South America dogs

are still the most important vectors, but in

many countries wild animals provide a reservoir

of infection, and infect dogs and cats and farm

animals – which in turn may infect man, who

is an incidental host of the disease (See table of

vectors.)

Public healthRabies is virtually always fatal in

the human being, and there is danger not only

from being bitten by rabid animals, but also from

contamination by their saliva of wounds, cut

fingers, eyes, etc Scratches may convey infection

as well as bites

People have died from rabies following attacks

by rabid dogs, cats, foxes, wolves, badgers,

skunks, racoons, mongooses, bats, rodents, etc

Pet animals, such as rabbits, may be bitten by

rabid animals and themselves become rabid;

and it has sometimes happened that wild or

exotic animals (originating in countries where

rabies is endemic) were bought as pets while in

the incubation stage of rabies, with unfortunate

results

In the UK as in most other countries, rabies

is a NOTIFIABLE DISEASE, and must be reported

to DEFRA or to the police Bitten personsshould seek medical advice immediately

Cause A Lyssavirus (one of the Rhabdovirusgroup) When it is injected into the tissues,either naturally (from a bite) or artificially, thevirus passes along the nerves and reaches thecentral nervous system The time elapsingbetween infection and onset of symptoms variesgreatly with the location of the bite, its severity,and – no doubt – the quantity of virus in thesaliva In the most rapidly developing cases thesymptoms may be shown as early as the 9th day after being bitten, and at the other extreme,cases have appeared several months after theincident It is owing to this fact that the 6-months period of quarantine insisted upon

in Britain is something of a compromise Theaverage incubation periods in dogs, sheep, andswine are from 15 to 60 days; in horses and cattle, from 30 to 80 days In young animals theperiod of incubation is shorter than in adults

Signs

DogThere are 2 distinct forms of rabies in thedog – the ‘furious’ and the ‘dumb’; but these are in reality 2 stages only It is customary toconsider 3 stages of typical symptoms

(1) Melancholy The prodromal dull stage isoften not noticed, or, if it is, only scant attention

is paid to it The habits of the dog change

It becomes morose and sulky, indifferent toauthority, disregards its usual playthings or com-panions, shows a tendency to hide in dark cor-ners, and may appear itchy or irritable as regardsits skin Noisy, boisterous animals become quietand dull, while animals that are normally of agentle, quiet disposition may become excitable.After 2 or 3 days of such behaviour the nextstage is reached

(2) Excitement The symptoms describedabove become exaggerated, and there is a ten-dency towards violence The dog pays no atten-tion to either cajoling or threatening Itbecomes easily excited and very uncertain in itsbehaviour Food is either disregarded complete-

ly or eaten with haste Vomiting is a not

uncommon symptom A fear of water is not a

symptom to expect in the rabid dog, which willoften drink or attempt to do so even when part-

ly paralysed After a time the appetite becomesderanged The dog refuses its ordinary food,but eats straw, stones, wood, coal, carpet, pieces

of sacking, etc., with great avidity If the animal

is shut up in a kennel, it persists continually inits efforts to escape Should it be released orshould it escape, it almost invariably runs away

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Rabies in wild animals – principal

vectors in various regions

badgers, martensAsia Wolves, jackals, bats,

mongoosesNorth America Foxes, skunks,

coyotes, batsCentral America Bats

South America and

Trinidad Vampire bats

from home It may wander for long distances.

In its travels it bites and snaps at objects which

it encounters, real or imaginary, animate or

inanimate Some rabid dogs bite several people

The tone of voice is altered

The face has a vacant stare, the eyes are fixed

and expressionless, and the pupils are dilated

This stage lasts from 2 to 4 days, unless the dog’s

strength gives out sooner, and the next stage

appears

(3) Paralysis The characteristics of the last

stage in the train of symptoms of rabies are

those of paralysis, especially of the lower jaw

and the hindquarters The dog begins to stagger

in its gait, and finally falls It may manage to

regain its feet when stimulated, but soon falls

again The lower jaw drops, the tongue lolls out

of the mouth, and there is great salivation The

muscles of the throat and larynx are soon

involved in the progressive paralysis

The dumb form of rabies consists of this

par-alytic stage – the stage of excitation having been

omitted The dumb form is the more common

in the dog: barking ceases – hence the name

Vomiting may suggest merely a digestive upset

Protrusion of the nictitating membrane partly

across the eye, together with a dropped jaw, i.e

partly opened mouth which can be closed by

gently raising the lower jaw by means of a stick,

are highly suggestive of rabies

In parts of Africa and Asia, the classical form

of rabies in dogs (described above) is replaced

by a form called (in Africa) ‘OULOU FATO’

Cat In this animal the furious form is more

common than in the dog The aggressive stage is

most marked, the cat attacking other animals

and man with great vigour, and attempting to

injure their faces with teeth or claws Sometimes

the rabid cat will at first show extra affection

The course of the disease is usually shorter than

in the dog

It is worth mentioning that occasionally dogs

and cats die from rabies without any observed

symptoms They may be found dead or dying

It is not unknown for a cat to be found lying in

a field or garden unable to walk but still able to

bite

Cattle These animals are usually affected

through having been bitten by a rabid fox or

dog The stage of excitement is short and the

dumb stage most evident Affected cattle

behave in an unusual manner; they may stamp

or bellow, salivate from the mouth, break loose,

and may do much damage Rumination and

milk production cease, muscular quiverings are

seen, sexual excitement is noticed, and there is

a great loss of condition Exhaustion soon lows and paralysis sets in Death occurs within

fol-2 to 6 days or more after the commencement ofthe condition

Rabies may be mistaken for saemia, milk fever, botulism, anaplasmosis, listeriosis, lead poisoning, choking, etc

hypomagne-In Central and South America, cattle areinfected with rabies by vampire bats, and mayshow long streaks of blood on their shoulders,necks and backs

Sheep, goats and swineThe sheep and thegoat are affected in a manner similar to cattle, butthe stage of excitement is shorter or absent, andthe dumb paralytic stage is more often noticed.Pigs become excitable; they may squeal and showmuscular spasms before paralysis ensues

HorseThe furious form is common but theanimal may appear calm between bouts ofaggressiveness Dumb forms also occur andmay be mistaken for colic, paresis or encephali-tis from other causes Signs may include a facialtwitch, biting of woodwork or self-mutilation,head-tossing, frequent whinnying, abnormalposture, apparent lameness, ataxia, paralysis ofhindquarters The horse may continue to eatand drink until shortly before death The tone

of voice may be altered

DiagnosisThe routine examination for Negribodies has now in most countries been super-seded by the fluorescent antibody test, withconfirmation by mouse inoculation if necessary.(If a dog which bit someone is still alive after

10 days, it cannot be assumed that the dog is

not rabid.)

Differentiation between laboratory andstreet rabies virus, between rabies vaccine virusand street virus, and between rabies virus andrabies-like viruses (e.g Mokola, Lagos bat, andDuvenhage viruses) is possible by laboratorytests based on differentiation of monoclonalantibodies

PreventionPrevention of the disease in manand animals stems from the research of LouisPasteur in the 1880s He discovered the process

of attenuation, by which the virulence of amicro-organism is reduced but not its ability

to produce antibodies against disease Pasteurachieved this by infecting rabbits with rabiesfrom a dog Although this was fatal to the rabbits, dogs survived infection with the rabbitvirus Tissue from the spinal cord of an infect-

ed rabbit was then used to prepare a vaccine

Rabies 583

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His triumph came in 1885 when the vaccine

saved the lives of 2 badly bitten boys

In the intervening years many modifications

have been made, and new techniques developed,

to make rabies vaccines which would be safe and

free from dangerous side-effects, and so could be

used to immunise people and animals against

rabies (‘pre-exposure’ – vaccination), as well as

provide ‘post-exposure’ treatment of those bitten

by rabid animals

The table shows examples of vaccines

pre-pared from tissue culture cells The last one,

the Merieux, was developed by the Merieux

Institute of France using a technique pioneered

at the Wistar Institute of Philadelphia Only

1 ml doses are required, and 2 injections (apart

from any booster doses) (See also VERO CELLS.)

In the UK, 2 vaccines approved for use in

dogs and cats: Rabisin rabies vaccine (Merial)

containing inactivated GS-57 Wistar virus

strain; and Nobivac Rabies (Intervet) prepared

from virus grown on cell-line tissue culture

Mass vaccination of dogs is carried out in

many countries as a control measure; and in

Central and South America, cattle on ranches

are vaccinated against vampire-bat-transmitted

rabies In France and other countries of

Europe, hundreds of thousands of cattle are

vaccinated against rabies (often a combined

rabies/foot-and-mouth disease inoculation)

It must be remembered, however, that no

vac-cines are 100 per cent effective, that certificates

of vaccination can be forged, and that

conse-quently it is still essential to control the import

of animals, whether vaccinated or not, and to

enforce quarantine measures where appropriate

Control of rabies in BritainFrom 1902

until 1918, no cases occurred in the British Isles;

but in that year infected dogs were smuggled

from the Continent, and the disease obtained

a fresh hold for a period of little more than

3 years Britain had been free since then, but in

1969 a dog released from quarantine 10 days lier showed symptoms of rabies and bit 2 people

ear-at Camberley, Surrey; a 2nd case occurred in

1970 In 1965 there was a case in a recentlyimported leopard in quarantine at EdinburghZoo In Britain, in 1969, the danger of allowingthe importation of rabies-susceptible exotic ani-mals, for sale as pets or for research, was official-

ly recognised, and the quarantine regulationsamended to include monkeys, mongooses, etc.Following strong pressure to replace quaran-tine for pet dogs with a vaccination/identifica-tion policy, a government committee was set up

in 1997 to examine the issue The committeerecommended that a strict scheme of medicalexamination, rabies vaccination and veterinarycertification should replace the compulsoryquarantine regulations for dogs and cats Therecommendation was accepted and an arrange-ment introduced in 2000 under which dogs andcats may travel to and from the UK and specifiedcountries without quarantine under the PET TRAVEL SCHEME (See also IMPORTING/EXPORTING ANIMALS.)

Other points to note: (1) the saliva is times infective before symptoms of rabies appear– a hazard for a person licked; (2) farmers havedied through mistaking rabies for ‘choking’ and,with abraded fingers, examining their cow’smouths; (3) non-typical cases of rabies are notuncommon; (4) a dog may bite a small child orhousehold pet and promptly run away – rabiesnot being suspected, though running away is initself a canine symptom; (5) the virus may be pre-sent in semen, as well as in milk, tears, faeces, andurine; and (6) subclinical rabies, and a ‘carrier’state, have long been recognised in Africa (see

some-‘OULOU FATO’) and in Asia

Vaccination of foxeshas been an ing success in controlling the disease in WesternEurope Currently Britain, Andorra, Ireland,

outstand-584 Rabies

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Examples of rabies vaccines prepared from tissue culture cells

and other animals

Inactivated:

and other animalsHamster embryo Cats, dogs, horses,

cattle and sheep

Italy, Netherlands, Norway, Sweden, Denmark,

Greece, Spain and Portugal are all rabies-free

There are still black spots in Germany, while

there are enzootic areas in Poland and Turkey

The oral vaccine is genetically engineered on

vaccinia virus so that the antigen to rabies is

absorbed from the intestine The vaccine is put

into fish-flavoured capsules scattered from

heli-copters In the areas so treated, up to 93 per cent

of foxes, stoats, weasels, polecats and badgers

caught and bloodsampled have been found to

have taken up the vaccine

Rabies (Control) Order 1974

This gives powers to deal with an outbreak of

rabies outside quarantine premises In a declared

infected area, an order may be made for the

destruction of foxes and other wild mammals,

and for access to land for this purpose Fences or

other types of barrier may be erected to restrict

movement of animals into or out of an area

while such destruction is in progress

Orders may be made for compulsory

vacci-nation, confinement, and control of domestic

animals, including strays Anyone knowing or

suspecting that an animal has rabies must

noti-fy that suspicion to the police Deaths of

ani-mals in an infected area must also be notified,

and the authorities can take over ownership of

carcases and determine the means of their

dis-posal This is because it is essential to confirm

a diagnosis of rabies, so that precautions can

be taken concerning in-contact animals and

human beings The order can override a

dog-owner’s reluctance or refusal to part with the

body of a dead pet or working dog

The Rabies (Importation of Mammals)

Order 1974prohibits the landing of

suscepti-ble mammals in Britain unless from Ireland, Isle

of Man, or the Channel Islands Any animal

brought in from elsewhere has to undergo a

peri-od of quarantine Imported animals are

vacci-nated while in quarantine as a precaution against

a quarantined animal developing the disease

Those animals not a threat to human health

(ruminants, pigs and horses) do not go into

quarantine for rabies but may be quarantined for

other diseases Control under the Order is

exer-cised on the transport of imported susceptible

animals within Britain

If an animal is landed at a port or airport not

authorised to receive such animals, that

consti-tutes an illegal landing even if the circumstances

are outside anyone’s control (e.g if an airport is

fogbound)

Under a 1984 amendment order, animals

which have not been in contact with another

animal (e.g have been on an oil rig) are ted to be landed in Britain A similar relaxationapplies to animals belonging to the police,Customs & Excise and H.M Forces, if the ani-mal has been abroad but under the constant con-trol of a trained handler while outside Britain.(See also PET TRAVEL SCHEME (PETS).)

permit-Rabies-Related Viruses

These include Duvenhage virus, the cause in

fruit-eating bats of a disease very similar to

rabies; the Mokola virus, which has been

isolat-ed from shrews, and causes nervous symptoms

in man; the Lagos bat virus; the Nigerian horse

virus and Lyssa virus.

Raccoons

Raccoons are, in Canada and the USA, amongthe wildlife creatures which sometimes transmitrabies

A dog bitten by a (non-rabid) raccoon maybecome paralysed in all 4 limbs (quadriplegia)

Racehorses

Every year between 1400 and 1600 bred mares go to stud in the UK About 67 percent of them foal successfully, and for every 1000mares covered, 270 or so of the resulting progenyfinally appear on the racecourse Temperament,unsoundness, or sale abroad account for the non-appearance of more in the UK

thorough-An epidemiological study of wastage amongracehorses has been conducted among 6 stables,

5 of which were in Newmarket The basis of thesurvey was the inability of horses to take part incantering exercise as a result of injury or disease.The greatest number of days lost to training wascaused by lameness (67.5 per cent) and respira-tory problems (20.5 per cent) Conditions of thefoot (19 per cent), muscle (18 per cent), carpus(14 per cent), fetlock joints (14 per cent), tendons (10 per cent) and sore shins (9 per cent)were the major reasons for training days beinglost in 198 cases in which a positive diagnosis ofthe site of lameness was made

Pulmonary haemorrhage In horseswhich show blood at their nostrils after exercisesuch as racing, the blood does not come fromthe nasal cavity but from the lungs Endoscopicexamination showed an incidence of 42 percent in a group of horses with only 15 per centshowing blood at the nostrils Affected horsesmight appear distressed, with dilated pupils.Exercise-induced pulmonary haemorrhagewas observed in 23 of 49 endoscopic examina-tions after high-speed training, in 9 of 37 exam-inations after cantering, and in 1 of 17 after

Racehorses 585

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walking or trotting; it was not possible to

pre-dict its occurrence Mucoid or mucopurulent

exudate was observed in 60 of 118 examinations

and the amount increased after exercise

Pulmonary haemorrhage was diagnosed by

endoscopic examination in 255 2-year-old

quar-terhorses after racing Only 9 (3.5 per cent) of

the animals had visible epistaxis

Fatal pulmonary haemorrhage occurred in a

racehorse which panicked as the aircraft in which

it was travelling landed

(See HORSES,BREEDS OF;HORSES;EXERCISING

Radial paralysis (‘dropped elbow’) is

common-est in horses and dogs, though it may be seen in

any animal

CausesProbably the majority of cases are due

to a fracture of the 1st rib on the same side of

the body, the broken ends of the rib lacerating

the nerve-fibres as they pass the rib, or pressing

against them In other cases the origin of the

paralysis seems to be situated in the end-plates

of the nerve-fibres where they are distributed to

the muscles, and in some cases a neuritis

involv-ing the radial nerve, or a tumour pressinvolv-ing upon

it at some part of its course, is responsible for

producing the condition

SignsIn a typical case the horse stands with the

elbow dropped lower than normally, and with

the knee, elbow, and fetlock joints flexed Little

or no pain is felt, unless there is a fractured rib,

or some inflammatory condition which has

caused the paralysis The limb is held in the

position assumed at the commencement of a

stride, but the animal is incapable of advancing

it far in front of the sound limb No weight is

borne upon the leg, the muscles are flaccid and

soft, and if the horse is made to move forward

either it does so by hopping off and on to the

sound fore-limb, or it may fall forwards If the

hand be forcibly pressed against the knee, so

that the limb is restored to its natural upright

position, the horse is able to bear weight upon it

and may lift the other limb from the ground,

but as soon as the pressure is released, the joints

fall forward again Sometimes the toe is rested

upon the ground, but at other times the horse

stands with the wall of the foot in contact with

the ground In cases that are not so severe, the

flat of the foot may rest on the ground, and the

limb can be advanced forwards to a considerableextent

TreatmentThe majority of such cases as thesewill recover in a few weeks Patience on the part

of the owner is essential

Radiation, Exposure to

The 1986 Chernobyl nuclear power-station aster in the former USSR led to controls beingimposed on the movement and slaughter ofsheep in parts of Scotland, Cumbria, and Wales,after between 1000 and 4000 Becquerels/kg ofcaesium-137 had been detected in lambs.Similar controls were applied in other countriesaffected by the fallout The ban temporarilyaffected about 2 million sheep and lambs insome 500 flocks

dis-The Atomic Energy Authority stated that10,000 Bq/kg represents a health risk

However, the contamination figures

exceed-ed, in 9 cases, the internationally recommendedaction levels for radiocaesium of 1000 Bq/kg.The highest figure was 4000

‘Although the physical half-life of sium is 30 years, its biological half-life is muchshorter In an adult animal, the half-life is esti-mated at between 30 and 100 days, but for lamb

radiocae-it would be between 25 and 50 days.’ (MAFF)(See also RADIOACTIVE IODINE;RADIOACTIVE STRONTIUM.)

Annual human exposureOf the average

UK citizen’s annual exposure to radioactive charges, only 0.1 per cent comes from the nuclearpower industry, according to the RadiologicalProtection Board

dis-For radiation exposure associated with nary practice, see RADIOISOTOPES and X-RAYS.Carbon-14 is among internal sources of nat-ural radiation, and is present in the humanbody to the extent of about 2000 Bq

veteri-Radiation, Protection against

Regulations governing the use of X-ray ment, and the precautions to be taken by thosehandling it, are very strict Details are given

equip-in the Health and Safety at Work Act (See under X-RAYS.)

A concise guide to the Health and Safety atWork Act 1974 can be obtained from HSEBooks, PO Box 1999, Sudbury, Suffolk COI06FS

Radiation Sickness

Dogs exposed to radiation following a nuclearexplosion will vomit as a result of gastroenteri-tis, become dull and lose their appetite This

586 Rachitis

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may return after a day or two, but leucopenia

develops, and may be followed by haemorrhage

or septicaemia

Radioactive Caesium

High levels of caesium 137 were found in areas

of Wales and Scotland following the nuclear

power-station explosion at Chernobyl in 1986

Certain flocks of sheep were affected by the

fall-out and the meat declared unfit for human

consumption for some time

AntidoteA ferric-cyano-ferrate (AFCF), in the

form of a dark blue powder, can bind

radiocae-sium both in vitro and in the gastrointestinal tract

of animals very effectively, preventing the isotope

from being absorbed and secreted into the milk

or transferred to the meat of cows, etc The

addi-tion of only 3 g AFCF per day to the diet of

lactating cows reduced the radiocaesium content

of their milk by between 80 and 90 per cent, and

of their meat by 78 per cent

The radiocaesium content of the meat from

sheep fed 1 g AFCF per day or of calves or pigs

fed 2 g AFCF per day was reduced by

approxi-mately 90 per cent The compound was given

official clearance as a feed additive against

radio-caesium in Germany

Radioactive Discharges

Of the average UK citizen’s annual exposure, only

0.1 per cent comes from the nuclear power

indus-try, according to the Radiological Protection

Board

Around 90 per cent comes from natural

sources, principally radon gas released from

building materials

For radiation associated with veterinary practice,

see RADIOISOTOPES and X-RAYS

Radioactive Fall-Out

Radioactive fall-out, following the explosion of

nuclear bombs, etc., or accidents at atomic plant,

may be dangerous to farm livestock on account

of the radioactive iodine and strontium released

After an accident at Windscale, radioactive

iodine alone contaminated pasture in the area

(See also RADIATION, EXPOSURE TO; RADIATION

SICKNESS;RADIOACTIVE IODINE.)

Radioactive Iodine

Cattle grazing pasture contaminated by fall-out

pick up 10 times as much radioactive iodine as

do people in the same locality, according to

American reports Much is excreted in the milk,

and much concentrated in the thyroid glands

Feeding-stuffs or pasture contaminated by

fall-out containing radioactive iodine and

strontium may give rise to illness in cattle.Digestive organs may be damaged, changes inthe blood occur, and deaths follow within amonth or so, after a period of dullness andscouring (See RADIOACTIVE STRONTIUM.)

Radioactive Strontium

Whereas the half-life of radioactive iodine is amatter of days, that of strontium is 30 years.Following the grazing of contaminated pasture

or the eating of other contaminated feed,radioactive strontium is excreted in the milk,but much of it enters the bones and is liable toset up cancer many years afterwards

The UK average ratio of strontium-90 to calcium in milk was 2.8 picocuries per gram ofcalcium in 1975, compared with 3.3 picocuriesper gram in the previous year; this result isabout one-tenth of the maximum reached in

1964 The average concentration of

caesium-137 (7 picocuries/litre) was about four-fifths ofthe value in 1974 and less than one-twentieth

of the 1964 maximum (AFRC.)

Radioisotopes

A radioisotope is a form of an element thatundergoes decay while emitting radiation.Artificial radioisotopes (radiopharmaceuticals)are widely used in diagnosis and in humanmedicine Nuclear medicine involves the use

of unsealed radioisotopes for diagnosis andtherapy For example, in bone scanning, themost commonly used radiopharmaceutical ismethylene diphosphonate, labelled withTechnetium 99 mm (Tc-99) With a half-life ofonly 6 hours, high doses can be given for a lowradiation burden, permitting high resolutionpictures to be obtained

Radio ‘Pills’ (Telemetering Capsules)

Radio ‘pills’ (telemetering capsules) have beendeveloped for research purposes A radio trans-mitter, the size of an ordinary drug capsule, can give information concerning pressure, temperature or pH within an organ

Radio ‘Pills’ (Telemetering Capsules) 587

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The inner of the 2 bones of the fore-limb

In the horse and ox particularly, the radius

forms the main bone of this part, the ulna being

much smaller and not taking part in

weight-bearing (See BONE.)

Radon

A colourless gas produced by the disintegration

of radium It is found naturally in low

concen-trations in certain areas, e.g parts of Cornwall,

where it has given rise to public-health concerns

(see under RADIOACTIVE)

Ragdoll

A breed of cat originating in the USA, so called

because it tends to ‘flop’ if carried They have a

high pain threshold and, if involved in a fight,

could continue long after a normal cat would

have stopped As a result, it could sustain serious

injuries even if it won the fight

Ragwort Poisoning

Ragwort poisoning causes losses among cattle

and sheep in Great Britain, Canada, and New

Zealand It is the cause of the ‘Pictou cattle

disease of Canada’, and of ‘Molteno cattle

dis-ease’ in South Africa The plant (Senecio

jacobaea, or sp.) is very often fed off by sheep

when it becomes too plentiful in grass land In

the UK fatal poisoning has followed the giving

of hay contaminated with ragwort – death

occurring many weeks after the last mouthful

The death of 28 head of cattle was caused 2 to

4 months after feeding ragwort-contaminated

silage Acute ragwort poisoning may also occur,

causing death in 5 to 10 days with symptoms

of dullness, abdominal pain, and sometimes

jaundice

Ragwort contains PYRROLIZIDENE ALKALOIDS,

which produce cirrhosis of the liver,

inflamma-tion of the 4th stomach, and other lesions

In grazing horses, ragwort will be eaten only

if other food is not available but may be

ingest-ed in hay or silage In the UK after a mild, damp

winter, when the plant grows earlier in the year

than usual, and is sprouting among the grasses,

horses may eat it

Chronic liver damage may result, with acute

signs apparent when the cirrhosis becomes

advanced

Milk from a cow which has eaten ragwort may

be dangerous to children, causing liver damage

Signsinclude loss of appetite and of condition,

constipation, sometimes jaundice Cattle may

strain and later become excited and violent;

horses may become drowsy, with a staggering

gait Secondary gastric impaction and rupture

in horses has been reported

TreatmentThere is no specific antidote, butmethionine has been reported to be helpful (See LIVER,DISEASES OF.)

Diagnosis A liver biopsy may be helpful inthe diagnosis of chronic ragwort poisoning inhorses – ‘probably the most common cause ofchronic hepatic pathology in horses in the UK’

‘Rain Scald’

An old name for Dermatophilus infection in

horses subjected to prolonged wetting Lesionsoccur on withers, shoulders, and rump Forappearance of the lesions, see under GREASY HEEL,

and DERMATOPHILUS

Rainfall

Rainfall may influence outbreaks of NESAEMIA;BLOAT;FOOT-AND-MOUTH DISEASE

HYPOMAG-Rales (Moist Sounds)

Rales (moist sounds) are sounds heard by cultation of the chest during various diseases.They are divided into 2 main classes: (1) crepi-tant or vesicular rales, which are heard in the 1st stages of pneumonia, and are sharp, fine,crackling noises noticed during inspirationonly; and (2) mucous rales, which are heardduring expiration as well as during inspirationand may be described as bubbling or gurglingsounds

aus-Ram Epididymitis

This is a disease of economic importance inmost of the sheep-farming areas of the world,including Australia and Mediterranean Europe,

but not the UK The cause is Brucella ovis.

Diagnosis by clinical means (palpation, mainly)

is not very satisfactory Laboratory tests to firm the organism confirm the diagnosis.Vaccination and culling are methods of control,but vaccination is not free from problems.Contagious epididymitis is a NOTIFIABLE DISEASEthroughout the EU

con-Rancidity

Rancidity of cod-liver oil or other fish oils, etc.,can be extremely dangerous Rancid mash maybring about deficiencies of vitamins A, D, and

E, with acute digestive disorders and death

in chicks Growing and adult birds may alsosuffer losses from this cause; with osteomalacia,and decreased egg production (See also under VITAMIN E.)

588 Radius

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Rangoon Beans

(see JAVA BEAN POISONING)

Ranula

Ranula is a swelling which sometimes appears

below the free portion of the dog’s tongue It is

caused by a collection of saliva in one of the small

ducts that carry saliva from the glands below the

tongue, or further back, into the mouth, and

when of some size a ranula may cause

consider-able interference with feeding It is treated by

incision or excision, and is usually not serious

Rape Poisoning

Rape poisoning occurs in animals which are

not given hay or other food in addition to rape

Poisoning can be extremely serious, especially

in sheep

Signs include dullness, red-coloured urine,

and blindness In one outbreak reported by the

Reading VI Centre, 36 out of 360 sheep died

from rape poisoning

A form of light sensitisation called ‘rape scald’

occurs in sheep on rape Swelling of the head

occurs, there is irritation leading to rubbing, the

ears may suffer damage Jaundice may occur

Rapeseed Cake

A compressed ‘cake’ of rapeseed is used as a

cattle feed The oil is first removed and the cake

may be processed to remove any toxicity

Rapeseed Oil

This has been shown experimentally to be toxic

to the hearts of rats The degree of toxicity

varies according to the erucic acid content of

the oil, and perhaps to closely related

mono-ethylenic acids (e.g cetoleic and nervonic) It is

apparently the breakdown of erucic acid in the

myocardium and skeletal muscles which

pro-duces the damaging effects The use of the oil in

margarine manufacture and as a substitute for

more expensive olive oil has led to anxiety over

the effects on the human heart

Rapeseed mealfed to poultry may depress

growth and egg yield, and cause hypertrophy of

the thyroid gland, liver haemorrhage,

abnormal-ities of the skeleton, and a fishy taint in the eggs

The liver haemorrhages resemble those

associat-ed with the ‘fatty liver/haemorrhagic syndrome’

Rapeseeds of low toxicity, such as the Canadian

variety canola, have now been bred

Raphe

Raphe means a ridge or furrow between the

halves of an organ

Rarefaction of Bone

A decrease in the mineral content

Rat and Mouse Poisons

(see under RODENTS)

Rat-Bite Fever

This is a disease recognised in man and caused,following the bite of a rat (or, sometimes, dog,cat, mouse, weasel, or squirrel), by infection with

Spirillum minus or Streptobacillus moniliformis In

addition to fever there may be an extensive rash

Rations for LivestockDairy cattle

Winter rationing The home-grown foodsavailable naturally vary from farm to farm Farm-mixed rations often make good use of barley.Proprietary compound feeding-stuffs are wellbalanced and formulated to contain all necessaryingredients such as vitamins, trace elements, etc.,and are nowadays extensively used Proprietarybarley balancers and straw balancers are alsomuch used (See also under WINTER DIET.)

Rations: theoretical basis for tionTraditionally, it is customary to regard theration as being composed of 2 parts: (1) the

calcula-‘maintenance’ part, which provides the materialfor all vital activities and makes good the nor-mal wear and tear of the body without causingincrease or decrease in liveweight; and (2) the

‘production’ part, which supplies the materialsused for increase in body size, fat production,growth of the fetus, and milk production

ADAS Advisory Paper No 11, Nutrient

Allowances and Composition of Feeding-Stuffs for Ruminants, contains 2 valuable sets of informa-

tion: firstly, what different classes and weights

of ruminant stock need for maintenance andproduction; and secondly, the analyses of a widevariety of feeds

Maintenance and 4.5 litre (1 gallon) rationsfor cows of Friesian breed or similar:

kg (lb)

Brewer’s grains 4.5 (10)Dried sugar beet pulp 1.8 (4)

Ryegrass/lucerne haylage ad lib

Rations for Livestock 589

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Brewer’s grains plus minerals 7 kg (15 lb)

with every 1.8 kg (4 lb) hammer-milled maize

fed in parlour for every additional 4.5 litres

(1 gallon)

Summer rationingGrass is the standard

sum-mer food for cattle On a good, well-managed

pasture – where over-stocking is avoided – young,

leafy grass will supply enough protein for high

yielders, but they will require additional

carbohy-drate This may be supplied in the form of

cere-als, e.g 1.8 kg (4 lb) for each 4.5 litres (1 gallon)

of milk over about 20 litres (4H gallons)

produced per day

It has been recommended that in April, cows

grazing young, leafy grass 10 to 15 cm (4 to

6 inches) high for 4 hours daily, should receive

3 kg (7 lb) hay and cereals (plus a mineral

mixture) at the rate of 1.8 kg (4 lb) for each

4.5 litres (1 gallon) over 13.5 litres (3 gallons)

In May, with unrestricted grazing of grass 20 or

25 cm (8 or 10 inches) long at the pre-flowering

stage, the hay is discontinued; the cereal ration

remaining as before In June and July, with grass

at the flowering stage, the cows receive balanced

concentrates for yields over 11 litres (21⁄2

gallons) (June), then over 9 litres (2 gallons) In

August, grazing aftermath (or green fodder ing a drought), the cows receive concentrates foreach 4.5 litres (1 gallon) over the first 4.5 litres(1 gallon) In September, with young aftermath

dur-or maiden seeds, there is a hay ration of 3 kg (7 lb) (or 13 kg (28 lb) kale) plus concentratesfor yields over 9 litres (2 gallons) per day.More sophisticated calculations for feedrequirements are based on the metabolisableenergy requirements of specific herds or even ani-mals Calculations take into account the amount

of energy required for maintaining condition; thequantity of milk produced; and the stage of preg-nancy For growing cattle, rations are calculatedbased on the maintenance requirement plus thedaily liveweight gain

Beef cattle(see table re suckler cows,and under BEEF)

Calves(see CALF-REARING)

Rations for suckler cows

per day so that

Breeders and growers* Per cent

*Plus mineral and vitamin supplements

Sheep(see under SHEEP, and FLUSHING OF EWES)

Horses(see under HORSES,FEEDING OF)

Rats are important from a veterinary point of

view as carriers of infection to cattle, pigs, dogs,

etc Examples of rat-borne diseases are:

Aujeszky’s, leptospirosis, salmonellosis,

ring-worm, trichinosis, and foot-and-mouth (See also

Receptors

These are or contain antibody molecules, occur

on the surface of lymphocytes, and enable cific antigens to be recognised (See under IMMUNE RESPONSE;BLOOD.)

spe-Physiological receptors include those forenzymes, and for hormones

Recessives

(see GENETICS)

Recombinant DNA Technology

A process by which genes from one organism aretransferred – usually by a modified bacterium orvirus – to another to reproduce a desirable char-acteristic For example, some vaccines are made

by modifying a virus so that its virulence isremoved but its antigenic potential – its ability

to confer immunity – remains Similarly, ria have been modified so that they producehuman insulin The possibility for using thetechnique to synthesize biological medicines notcurrently commercially available, or to improveplant breeds to enhance food yields, is likely tobecome increasingly important

bacte-Plants may also be modified so that desirablecharacteristics such as resistance to disease are

‘bred’ into them

Recovery Quilts

Recovery quilts for cats and dogs have beendeveloped Marketed as Flectabed, the quiltscontain Flectalon, a special fibre developed foremergency blankets It is stated that the prod-uct reflects back 95 per cent of the infra-redheat lost by the body Details from Flectabed,17a Moor Street, Chepstow, Gwent BP6 5DB

Rectum

The posterior end of the intestine It mences on a level with the anterior opening ofthe pelvis and extends to the anus, passingthrough the upper part of the pelvic cavity Inmost of the domesticated animals it possesses adilatation, known as the ‘ampulla’, which serves

com-to collect the faeces that are slowly passed incom-to

it from the colon, and holds them until timeand circumstances are convenient for theirevacuation to the outside (See INTESTINE.)

Rectum 591

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Rectum, Diseases of

With the exception of the dog, the domestic

animals are comparatively free from disease of

this part of the alimentary system

ImpactionThis occurs mainly in dogs (and to

a lesser extent in cats) when pieces of bone, string,

and other foreign materials form with the faeces

a hard mass The affected animal attempts to pass

faeces, but after considerable efforts fails to do so

If the impacted material contains spicules of bone

or other hard material, every effort at defaecation

causes the animal to cry out with the pain

Removal of the offending matter is effected by

the administration of an enema of glycerine, oil,

or soapy water, and the introduction of the gloved

finger Hard masses are broken up and taken

away in portions if too large to remove whole A

mild laxative should be given by the mouth after

the impacted material has been cleared from

the rectum, and the dog should receive a soft

semi-fluid diet for some days afterwards

Inflammation of the rectum may follow

impaction, or it may commence as the result of

an injury The animal frequently strains, and

the owner may surmise that it is constipated,

but exploration reveals the absence of faeces

Abscesses, tumours and ulcers may also affect

the rectum, but they are not common (See also

under ANUS.)

Prolapse of the rectum may occur in any

animal, but is especially common in the smaller

animals A portion of the gut is protruded from

the anus to an extent of a few inches It appears

as a tumorous swelling of a bright-red

appear-ance, cold to the touch, and usually covered with

mucus or faecal material There is usually some

straining when the condition is of recent origin,

but after a time the animal appears to become

used to the protrusion of the piece of bowel, and

only strains when it is handled or when attempts

are made to return it Anaesthesia or analgesia

will be needed It may be gently bathed with

warm water containing common salt in solution

(5 per cent) while awaiting assistance An

opera-tion, in which the rectum is sutured to some

part of the abdominal roof, is sometimes

neces-sary to prevent its recurrence after replacement

Prolapsed rectum is not uncommon in the horse

Sometimes it may be easily returned by placing

the neck of a quart bottle within the central

depression that is always present, and pressing

slowly and cautiously in a forward direction

In some instances amputation of the

pro-truded portion becomes necessary, especially if

it has been outside for some considerable timeand has become gangrenous

to paralysis of a horse’s hind-legs, necessitatingeuthanasia It has been suggested that a slightlyoblique dorsal recumbency is advisable.Anaesthetised horses, when positioned in left lateral recumbency, showed least muscle ornerve injuries when lying on a water mattress.Foam rubber was ‘far from satisfactory’

Recurrent Laryngeal Nerve

Recurrent laryngeal nerve is a branch of thevagus nerve which leaves the latter at differentpoints on the right and left sides of the body

On the right side it leaves the parent nerveopposite the 2nd rib, curves inwards round thesubclavian or the costo-cervical artery, and runs

up the neck on the lower surface of the tracheaand below the carotid of the same side In thecase of the left, the branch leaves the vaguswhere that nerve crosses the arch of the aorta,winds inwards around the concavity of the aortic arch, and runs up the neck in a positionsimilar to that of the right side Both nervessupply the muscles of the larynx which are concerned in the production of voice and inmaintaining the glottis open during ordinaryand forced respiration

‘Redfoot’

A condition seen in newborn lambs, in whichthe sensitive laminae of the feet become exposedowing to detachment of the overlying horn Thecause is unknown, no treatment effective, andthe lambs soon die

Red Squill

Preparations of the dried ground bulbs of the

sea onion Urginea maritima are used for

poi-soning rodents, baits being made up to contain

10 per cent red squill Domestic animals refrainfrom eating such preparations owing to thesmell and taste Symptoms of poisoning includeprofuse vomiting in the pig but not in the cat,excitement, muscular incoordination, and con-vulsions Poisoning in rodents by red squill may

be agonising and prolonged Its use in the UK

is banned

592 Rectum, Diseases of

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Red Urine

Causes of red discoloration of the urine

include: haematuria – blood in the urine, which

settles out on standing; haemoglobinuria – the

breakdown of red blood cells, in which urine

does not change colour on standing; and

pig-ments The coloration is usually a sign of

disease: pyelonephritis and cystitis cause

haematuria; red-water fever, leptospirosis,

infection with Clostridium haemolyticum, kale

and rape poisoning, copper poisoning, and the

drinking of very large quantities of water all

result in haemoglobinuria Azoturia results in

breakdown of muscles to produce

myoglobin-urea, a brown-red coloration Dosing with

phenothiazine produces a red pigment

Red-Water

Also called bacillary haemoglobinuria, or

ictero-haemoglobinuria, in the USA it occurs

in California, Colorado, Idaho, Louisiana,

Montana, Nevada, Oregon, Texas, and Utah

Clostridium haemolyticum is the cause (See also

TEXAS FEVER, the American red-water fever.)

Red-Water Fever

In the British Isles, babe siosis or piroplasmosis

(see under BABESIA), to give red-water fever its

proper names, is a disease of cattle and sheep,

due to the presence in the blood of a protozoonparasite which attacks the red blood cells,destroying their envelopes and liberatinghaemoglobin, which is excreted by the kidneysand colours the urine reddish or blackish Itoccurs mainly in the south and west ofEngland, in the north and west of Scotland,and practically all over Ireland, but it is alsoseen at times in districts that are not included inthese areas It is common in low-lying, rough-pastured, and moorland districts, where ticks,which harbour and transmit the parasite, canfind abundant shelter and suitable breedingplaces Cattle are usually attacked from the age

of about 6 months upwards, but young calvesare practically immune One attack gives adegree of immunity, and cattle that have beenbred upon infected farms, and from infectedcattle, are more resistant than those broughtfrom a clean district It is more prevalent in thespring and autumn months, since the ticks arethen at their maximum activity

CauseBabesia (Piroplasma) divergens This is

transmitted by the common tick Ixodes ricinus, and occasionally by Haemophysalis punctata.

(See under BABESIA and TICKS; also MUSCLES,

DISEASES OF;MYOGLOBINURIA.)

SignsTwo varieties of the disease are recognised:

an acute and a mild form

The acute type is sudden in its onset and frequently fatal The animal becomes very dulland depressed, separates itself from the rest of theherd, moves slowly or not at all, grunts, groans,arches its back, salivates freely, grinds its teeth,and often staggers and falls The coat becomeshard and staring, the skin is dry and often hide-bound, and there is almost always a profuse,watery, violent ‘pipe stem’ diarrhoea, due tospasms of the anal sphincter The temperaturerises to as high as 40.5° to 41.5° C (105° to

107°F), the pulse is fast and weak (often 100 perminute), and the respirations are laboured, blow-ing, and rapid (80 to 100 per minute) The visi-ble mucous membranes are pale After a few daysthe animal’s distress becomes less acute, and themost alarming symptoms subside The signs offever, however, are still evident, and the cow isstill in a serious condition The urine usuallyshows some degree of coloration, which variesfrom a clear reddish claret to a deep dark brown

or black – almost like stout

The duration of acute attacks varies, but it isseldom that the high temperature lasts for morethan a week Death may take place in from 3 to

5 days, or later on, when it is usually due toexhaustion

Red-Water Fever 593

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An electron microscope picture showing three

profiles of Babesia divergens – the cause of

red-water fever – inside the egg of a tick.

In the mild type the urine is not usually

highly coloured; there is only slight dullness

and loss of appetite The animals are ill for a

week or 10 days, and the only marked sequel is

anaemia

There are irregular forms of red-water met

with at times, in which the general symptoms are

similar to these seen in the typical acute attack,

but the urine does not become discoloured

Many of these cases end fatally

TreatmentImidocarb (Imizol) For use under

prescription only A single dose of 1 ml per

100 kg bodyweight for treatment, or 2.5 ml per

100 kg bodyweight for prevention; the dose

must be given subcutaneously Cattle must not

be slaughtered for human consumption for

90 days after administration, and milk from

treated animals must be withheld for 21 days

Veterinary surgeons who prescribe Imizol are

advised that:

1 Full records of product administration to

identifiable animals must be maintained, and

that it is the duty of the farmer to keep a

care-ful record of all administration of the product,

as required by the Animals and Fresh Meat

(Examination for Residues) Regulations 1988

2 The local DVM must be notified of the

address of the farm where treatment is to take

place

3 Farmers should be informed that they must

notify the local DVM when treated animals go

for slaughter for human consumption or when

milk from treated animals is intended for human

consumption

Any suspected adverse reactions, including

evidence of lack of efficacy, should be reported

to the Veterinary Medicines Directorate, New

Haw, Weybridge, Surrey, immediately

Ticks should be removed, either by

hand-picking or by spraying with a suitable parasiticide

(See TICKS,CONTROL OF.)

The few piroplasms taken into the

blood-stream, when young cattle are bitten by infected

ticks, tend not to multiply but to give rise to

a useful degree of immunity This may wane if

the piroplasms die, so that the animal becomes

susceptible again Immunity may likewise break

down if the animal becomes ill from some other

cause

Control Measures involve tick control, and

not mixing cattle from red-water areas with

susceptible cattle Even then there are risks

Twenty deaths occurred when local cattle

were placed on sea marsh land in Lincolnshire

that had previously been used for fattening

imported Irish steers which were carriers of

B divergens Cornish cattle brought to a farm in

Sussex set up a focus of infection because

infect-ed ticks became establishinfect-ed in the new habitat.And Simmental, Charolais and other Europeanbreeds are imported into Britain with noscreening for blood parasites

Red Worms

The common name for strongyles These cancause severe anaemia, unthriftiness, and debility.(See under FOALS,DISEASES OF; also under EQUINE VERMINOUS ARTERITIS; HORSES, WORMS IN.)Benzimidazoles, ivermectins and thiabendazoleare useful drugs for the removal of red worms.(See also ROUNDWORMS.)

Reduplication

Reduplication is a term applied to a duplication

of the normal heart-sounds as heard by tation There are heard a 1st and a 2nd sound

auscul-in a normal heartbeat, and auscul-in the above tion one or both of these may be doubled It isfound in certain diseases of the heart, such asobstruction of the valve between the auricle andventricle on the left side of the organ (the mitralvalve)

condi-Reflex Action

Reflex action is one of the simplest forms

of activity of the nervous system For the mechanism, see NERVES

Superficial reflexes are well instanced in thesudden shivering movement that is seen when

a fly or other insect settles upon the skin of ahorse, particularly in the region of the back ofthe shoulder

Visceral reflexes are those connected withvarious organs, such as the narrowing of thepupil when the eye is exposed to a bright light.(See SPINAL CORD.)

Regional Anaesthesia

This consists in the anaesthetisation of a region

of the body by means of a local anaesthetic tion injected either into the connective tissue sur-rounding a sensory nerve trunk or into the spinalcanal (See EPIDURAL ANAESTHESIA,ANALGESICS.)The most common example of perineurial injection is plantar block in the horse

solu-Register of Veterinary Surgeons

The Register of Veterinary Surgeons lists nary surgeons who can practise in the UK Itmay be consulted in some public libraries or isobtainable from the Royal College of VeterinarySurgeons, Belgravia House, 62–64 HorseferryRoad, London SW1P 2AF

veteri-594 Red Worms

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The restoration of the correct levels of water

and electrolytes in animals suffering from

DEHYDRATION

Reindeer (Rangifer Tarandus)

Both in northern Europe and North America

these animals are of economic importance

Parasites include WARBLES Subcutaneous

injec-tions of ivermectin are recommended for

prevention of infestation and treatment

Relapse

A relapse occasionally occurs when antibiotic

or sulfa drug treatment of an infectious disease

is stopped – the infection having been

sup-pressed but the animal’s powers of resistance

not having been stimulated to establish a

suffi-cient degree of immunity Some forms of

lame-ness are particularly liable to relapses, especially

those associated with sprains of tendons or

ligaments

Relative Breeding Value

(see PROGENY TESTING)

‘Remote Injection’ Method

(see PROJECTILE SYRINGE)

Renal

Relating to the kidney

Renin

An enzyme, secreted by the kidneys, which may

control the secretion of the hormone aldosterone

by the adrenal glands

Reovirus

The name derives from the words ‘respiratory

enteric orphan virus’ Reoviruses have

double-stranded ribonucleic acid (RNA), and will

repli-cate and produce changes in cells of cattle, pigs,

dogs, cats, rabbits, monkeys, and man Reovirus

in poultry is often seen as tenosynovitis The

tendon sheaths, synovial membrane and the

myocardium are all affected Vaccination is

possi-ble but attention to hygiene is also essential for

effective control Only flocks known to be free

from the infection should be selected for

produc-ing hatchproduc-ing eggs (See also CALF PNEUMONIA.)

Repair

Repair of tissue after injury is described under

WOUNDS; for the repair of special tissues, see

under BONE,MUSCLE,NERVE, etc (See also HOOF

REPAIR WITH PLASTICS.)

ReproductionOvulationAt OVULATIONthe Graafian folli-cle bursts, and the ovum is expelled by the rush

of the escaping fluid The cavity of the Graafianfollicle becomes filled with special cells to formthe corpus luteum, and the ovum begins itscareer as an absolute entity In normal circum-stances the fimbriated and dilated funnel-shaped end of the Fallopian tube, or oviduct, isapplied to the point at which a follicle willburst, so that upon escape of its ovum this latter may be caught and retained The dilatedend of the oviduct is usually known as thevestibule, and it is in this part that the spermusually meets the ovum and fertilises it (See also under OVARIES.)

CoitusThe act of copulation As mentionedunder OESTRUS, service by the male is onlyallowed during the period of oestrus by thefemales of the majority of species of higher animals At other times there is little or nodesire exhibited by the male, and all attentionsare resented by the female Artificial methods ofdomestication have to some extent modifiedthe frequency and duration of oestrus, so thatthe domestic animals sheltered under the pro-tection of man breed more frequently than dothe majority of wild animals of similar species.During a single ejaculation of an adult vigor-ous stallion about 80,000,000 sperms arereleased As soon as the sperms are free in theuterus or vagina, they travel towards whereverthe ovum is situated This they accomplishpartly by a kind of wriggling movement of theirtail, which drives them onwards always in thesame direction They are attracted to the ovum

by ‘chemotaxis’

FertilisationSomewhere in the oviduct, erally in its vestibule but not necessarily so, thespermatozoa arrive in the region of the waitingovum More than one sperm may penetrate thewall of the ovum, but except in rare instances(giving rise to PRIMARY MOSAICISM) only onesperm fertilises the ovum

gen-The sperm, having penetrated the ovum,loses its tail, which is no longer required, and lieswithin the protoplasm of the ovum The nucle-

us of the ovum and that of the head of the spermnow fuse, each contributing half the number ofchromosomes that are to be found present innearly all the cells of the future young animal.The fused body is known as the segmentationnucleus, and from it, when it begins to divide,all the body cells of the embryo are formed Theprocess of the formation of the young embryo is

Reproduction 595

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considered under EMBRYOLOGY (See also

TESTI-CLE;OVARIES;OESTRUS;BREEDING OF ANIMALS;

PREGNANCY;PARTURITION;PARTHENOGENESIS

Reproductive Organs

(see diagrams under UTERUS and PENIS)

Reptiles

A class of animal which includes tortoises,

lizards and snakes They tend to favour warm

places when they are ill Reptile housing should

be heated at all times, but a range of heat

should be available in different areas, within the

normal limits for the species, so that they can

choose which suits them best Under no

cir-cumstances must they be allowed to come into

direct contact with the heat source Many

species require ultraviolet light, otherwise bone

rarefaction (weakening) may occur; expert

advice must be sought before buying such a pet

(See also PETS.)

Resection

Resection is an operation in which a part of

some organ is removed – as, for example, the

resection of a piece of dead bone, or resection of

a part of the intestine which is diseased;

resec-tion of a rib in thoracotomy; aural resecresec-tion

done to overcome chronic disease of a dog’s ear

Resistance Transferability

(see under PLASMIDS;ANTIBIOTIC RESISTANCE)

Resistant Strains

This phrase is commonly used of bacteria which

are not sensitive to antibiotics, or of insects

which are not killed by an insecticide

Resorption

Mummification Resorption of the fetus occurs,

e.g in heifers receiving a high calcium and low

phosphorus diet In sows, mummification can

be a feature of Aujeszky’s disease, ‘blue-ear’

dis-ease (PRRS), and both African and classical

swine fever With the banning of sow stalls and

the need to find alternatives, it has been

report-ed that the level of mummification tends to

be higher in dry sows kept in straw yards The

reason is not clear, but bullying has been

suggested as a cause (See MUMMIFICATION.)

Respiration

(see also NOSE AND NASAL PASSAGES;LUNGS)

Mechanism of respirationFor the

struc-ture of the respiratory apparatus see NOSE AND

NASAL PASSAGES;LUNGS, etc

Inspirationis due to muscular effort whichenlarges the chest in all 3 dimensions, so thatthe lungs have to expand in order to fill up thevacuum that would otherwise be left; and since,although the lungs are not fixed to the chestwall, surface tension between the pleura liningthe chest and the pleura covering the lungs, hasmuch the same effect

In most vertebrates, except birds, the lungsare not normally attached to the walls of thechest, but are rather suspended in them fromtheir ‘roots’, so that there is no direct pull uponthe lungs when the chest cavity increases in size.The vertical diameter of the chest is increasedduring inspiration through the downward tilt-ing of the sternum This movement is best seen

in the dog when it is out of breath; at othertimes, and in other animals, it is so slight that

it escapes detection The transverse dimension

of the chest increases when any 1 of the ribsbehind the first 2 or 3 are forcibly pulled for-ward by muscular action Each rib only moves

a small amount, but the mass effect of the series

is considerable The muscles which bring aboutthese changes in ordinary inspiration are thediaphragm, the intercostal muscles which aresituated in two layers between each rib and itstwo neighbours, and possibly the levators of theribs, and the serratus muscles

When the chest expands, the lungs expandtoo; but initially the quantity of air within themremains the same Accordingly, the pressure falls,leading to an inflow of air

Expiration is in ordinary circumstancesmerely an elastic recoil, the diaphragm movingforward and the ribs settling back into theiroriginal positions, partly through muscularaction, and partly through the elasticity of theircartilages It occupies a slightly longer period oftime than does inspiration

Nervous control Respiration is usually

an automatic act under the control of the respiratory centre in the medulla oblongata.Although the respiratory centre is itself capa-ble of carrying on respiration, it is in its turnliable to be controlled by the higher consciouscentres This is seen particularly well in humanbeings, where it is possible to ‘hold the breath’,

or inhibit respiration for considerable periods

(when diving underwater, for example)

Rate of respirationThe speed of the

respi-ration varies with many internal and external

factors It is faster during fevers, after violent

exercise, or even after mild exercise (though it

soon returns to normal upon cessation); during

powerful emotions, such as fear, anger, sexual

excitement, etc.; during very cold or very hot

weather; when the body condition is very fat,

or when radiation is obstructed, through too

thick a covering of wool, fur, etc., or too much

clothing (See also ANAEMIA.)

It is slower than normal during resting, either

when merely lying or when sleeping; and in cases

of unconsciousness

The normal rates in adult domesticated

animals are as follows:

In each case, the larger the particular animal,

the slower it breathes, other things being equal

For instance, a Shetland pony respires about

12 times per minute, while a shire stallion

respires only 8 times; also, the young of any

species breathe faster than do adults; and

females breathe faster than males – especially

during pregnancy

When this air is taken into the lungs its

composition is altered, so that upon leaving the

lungs its CO2content is about 4 per cent greater

and its oxygen content about 4 per cent less

Quantity of airThe lungs do not by any

means completely empty themselves at each

expiration and refill at each inspiration What is

left after maximum expiration is called the

residual volume The volume of air exchanged

during normal breathing (i.e passing in and

out of the nose) is the tidal volume – about

5 litres in the horse The volume of air in the

airways leading to the alveoli of the lungs is

the anatomical dead space Air available for

the supply of oxygen in the lungs is the tidal

volume minus the anatomical dead space

Irregular forms of respiration Apart

from mere changes in rate and force, the

respi-ration is modified in various ways under certain

conditions Coughing is a series of violent

expi-rations, during each of which the larynx is at

first closed until the pressure of air in the lungs

and lower passages is considerably raised, and

then suddenly opened, so that the contained air

is released under pressure and rushes to the

out-side; its object is to expel some irritating object

from the air passages Sneezing is a single

sud-den expiration, which differs from coughing in

that the sudden rush of air is directed by the

soft palate up into the nose in order to expelsome source of irritation from the nasal cham-bers It is particularly well exhibited by the dog.Yawning is a deep slow inspiration followed

by a short expiration, the air being taken in

by the open mouth as well as by the nose.Hiccough is due to a sudden spasmodic con-traction of the diaphragm, along with a suddenclosing of the larynx, producing a sound notunlike a very loud heartbeat Hyperpnoea is aterm applied to the slightly increased frequencyand depth of respiration occurring during gentleexercise, or from some mild stimulus to the respiratory centre Dyspnoea means that there isdistinct distress in breathing, due to a morepowerful stimulus to the respiratory centre, and

is usually characterised by convulsive ments of the chest and diaphragm It is fre-quently the forerunner of asphyxia Apnoea isseen when there is a hyperoxygenation of the tis-sues, and consequently no further immediatedemands for oxygen It consists of a completecessation of the respiratory movements withoutthe exhibition of any distress It is artificiallyproduced in human beings when a diver takes

move-10 or 12 deep breaths before entering the water,where he must hold his breath It is not com-monly seen in the domestic animals, but the sealand other diving animals have developed thepower of inducing apnoea to a marked extent.(See also under ASTHMA; LARYNGEAL PARALYSIS;

VOICE;TACHYPNOEA.)

Respiratory Difficulty, Failure

(see under BREATHLESSNESS;ANAEMIA;OEDEMA;

ASPHYXIA; BRONCHITIS; PNEUMONIA; FOG FEVER; ANAESTHETICS.) Many poisons bringabout respiratory failure, e.g chloroform,hydrocyanic acid, paraquat

Respiratory Disease in Pigs

Pigs are susceptible to a number of respiratoryproblems; the most common being the following(see also undermain dictionary entries)

Atrophic rhinitisThis is generally agreed to

be the result of bacterial infection with Bordetella

bronchiseptica followed by toxigenic strains of Pasteurella multocida, leading to progressive

atrophy of the turbinate bones (see RHINITIS); avaccine is available A few cases are caused bycytomegalovirus (inclusion body rhinitis)

Enzootic pneumoniais a common lem, particularly in growing pigs; affected animals have a dry cough, reduced weight gainand poor feed conversion efficiency The cause

prob-is Mycoplasma hyopneumoniae.

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Pleuro-pneumonia of pigs is a rapid

onset respiratory disease resulting in dyspnoea

and, often, death in acute cases Less severely

affected animals have a variety of subclinical

problems The cause is Actinobacillus

pleuro-pneumoniae Often seen following other disease

problems, pleuro-pneumonia can affect only

some of the animals in a herd, causing high

temperatures, laboured breathing with, often, a

bloody frothy discharge from the nose Early

antibiotic treatment can effect a recovery;

tetra-cyclines, lincomycin and ceftiofur are among

drugs used Vaccines are available for control

Swine influenzacan sweep through a pig

unit, causing a variety of respiratory signs and

sometimes precipitating other respiratory

dis-eases Little can be done to control the spread of

infection, but the pigs recover after 4 to 6 days;

subsequent immunity lasts about 3 months

Porcine respiratory reproductive

dis-ease (PRRS) (‘blue-ear’ disdis-ease)results

in variable signs, but affected animals may

have respiratory difficulties; it often exacerbates

any underlying respiratory diseases, such as

pneumonias

Porcine respiratory-coronavirus

infec-tion (PRCV) Outbreaks are often relatively

mild, but other respiratory problems may result

Coughing, sneezing or dyspnoea can occur

Ascarids Infection with Ascaris suum can

result in coughing during the migratory stage of

the larvae

Aujeszky’s diseasesometimes causes

respi-ratory signs such as sneezing, coughing and nasal

discharge, occasionally with dyspnoea Vaccines

are available (in Ireland)

Lungworm Infection with Metastrongylus

apri is usually only a problem in outdoor pigs;

signs are often limited

Not all the factors involved in respiratory

disease are infections: management factors play

their part, too Space allowance per pig,

num-ber of pigs per group, effects of mixing and

crowding, temperature, humidity, nutrition,

age and genetic status of the pigs all exert their

effects (See also under ATROPHIC RHINITIS.)

Respiratory Stimulants

Respiratory stimulants are used to promote

breathing in the newborn and to relieve

respira-tory depression associated with, for example,

general anaesthesia They include doxapram

(Dopram V), cropropamide and crotethamide(Respirot), and etamiphylline (Dalophylline)

Respiratory Syncytial Virus

Respiratory syncytial virus was first isolated fromchimpanzees showing ‘cold-like’ signs; since themid-1950s it has been detected in clinical cases ofrespiratory disease in man, cattle, sheep, goats,and horses It is a cause of acute bronchiolitis andalveolitis

Restraint

In order to examine an animal thoroughly forsigns of injury or disease, in order to carry outinoculations, or even to administer an anaes-thetic, some form of restraint is often necessary.The introduction of effective tranquillisersand sedatives facilitated the handling of horses,cattle and small animals, and may assist orreplace the use of several means of restraintdescribed below (See also TRANQUILLISERS;

XYLAZINE;ANALGESIA.)The following methods should not be usedindiscriminately upon any and every animal

A method that is sufficient to restrain one animal may prove aggravating to another; e.g.while the common twitch may serve for a heavydraught gelding, it is likely to cause a thor-oughbred stallion to be more restive than ever

A person who finds it necessary to employ somemeans of restraint should first of all considerthe temperament, age, breed, and, if possible,the individual characteristics of the animal,

as well as the purpose of the restraint, beforedeciding upon what methods will be employed.Firm gentleness, a kindly spoken word, and ahand-pat, with a little coaxing or urging, willvery often allay an animal’s fears, but there arethose of a temperament which will not respond

to gentleness; it is to those particularly that suchmethods as described here are applicable

HorsesThe usual halter, head-stall, or bridle

is generally sufficient to control broken horsesthat are to be handled or examined without theinfliction of pain In some cases it may be nec-essary to tie the animal to a ring in the wall ormanger, or to the heel-posts, but it is better insuch cases to take a couple of turns round thering and have a man hold the end of the rope.For measures which involve handling of thehind-parts of the body, it is usually advisable tohave one of the fore-feet picked up and held(preferably that upon the same side of the body

as the operator is to work)

For greater control a TWITCHmay be applied.(See also TRANQUILLISERS;ANAESTHETICS.)

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CattleA cattle CRUSH; either of a commercial

pattern or one constructed of timber by farm

labour, is useful; a gate may be hinged to a wall

and closed so as to act as a crush for

inocula-tions, etc (See also VETERINARY FACILITIES ON

THE FARM.)

A halter is also useful in cattle, as in horses

In the case of comparatively quiet cattle, milk

cows, etc., it will generally suffice if an assistant

takes the animal by the nose The thumb and

middle finger of one hand are inserted into

the respective nostrils, and the nasal septum is

pinched between them It is important that the

stockman’s fingers do not block up the airway

The other hand may be placed under the

jaw In this position the majority of adult quiet

cattle can be easily held For bulls and those

cattle that are more difficult to control it is

usual to use a pair of bull-holders (‘bull-dogs’;

‘bull-tongs’); or if the animal is already rung

(with a copper or aluminium ring), to attach a

rope or bull-leader to the ring in the nose For

drenching purposes it is necessary to keep the

head and neck in as straight a line as possible

to obviate the risk of choking If an assistant

is needed he should stand on the opposite side

of the beast and take the horns in his hands

so that he may tilt the head upwards and at

the same time keep the head and neck straight

out A pair of bull-holders may be inserted

into the nostrils, and have a rope attached to

them which is passed over a beam and the head

pulled up

For lifting a hind-leg, a pole, broom handle,

etc., may be placed in front of that hock and

behind and above the other Two helpers take

hold of ends of the pole and pull the leg upwards

and backwards, at the same time steadying the

animal’s balance by leaning against its thighs with

their shoulders For the fore-feet it is usual to pass

a rope around the cannon or above the heels and

over the back to the opposite side, where it is

held by an assistant (See also TRANQUILLISERS.)

Sheep For most purposes the sheep may be

turned up into a position in which it sits upon

its rump, by placing the left hand round under

the neck from the near side, and the right hand

over the back to seize the wool of the abdomen,

lifting the animal’s fore-end off the ground and

twisting its hind-legs from under it In this

position its feet may be dressed, its fleece may

be examined, etc It is not advisable to turn

in-lamb ews, due to the possibility of harming

them or the fetus; they may be held against

a wall or fence by an assistant while their

feet, etc., are being dressed Sheep stocks are

sometimes used, or modern shearing tables

PigsThe adult pig is proverbially a difficultanimal to handle and restrain, especially whenthe handling involves pain or discomfort, butpiglets are easily held by the hind-legs with thehands, while the knees grip the dependenthead With large sows and boars it is wise toremember that they are apt to be vicious withstrangers, and to use a shield of wood or a hur-dle to prevent a rush by the angry animal

A method of securing a large pig is to drive itinto a corner and pen it there with a door, gate,

or heavy hurdle carried by 2 helpers, and held

so that the pig has no room to turn while anoose is dropped over its head and pulled tightround its jaws, and another is secured to a hind-leg above the hock The ends of theseropes are then passed round a post or a rail inthe fence and pulled tight when the pig isreleased from its corner

Dogs and cats These animals are usuallymore easily restrained than some of the largeranimals because of their intimate associationwith man, but there are certain animals thatpresent difficulty when angry or excited A kindword and a caress will often be necessary to gain the animal’s confidence before attempting

to examine it, and, wherever possible, severemethods of restraint should be avoided except

as a last resort The human voice often

exercis-es a degree of control over an excitable animal,and there are certain people who appear to pos-sess the faculty of immediately gaining almostany dog’s confidence and of being able to doanything with it

However, it is always wise in any case ofdoubt to take no risks The safest way of deal-ing with a dog is to muzzle it first A tape muz-zle may be applied; this is simply a piece of tape

or a bandage about 118 cm (3 ft) long whosemiddle is wound round the dog’s nose, the endsbeing crossed under the jaw and tied round theneck or on to the collar With bulldogs, andthose with a short face and a pug nose, it is better to tie the tape round the jaws, finishingwith the end above the nose, tying them togeth-

er there, and then passing the ends back to thecollar

Cats can be rolled in a sack or towel Withcats it is important to prevent them from usingtheir claws, which inflict injuries more oftenthan do the teeth (See also under TRANQUILLISERS;

ANAESTHETICS.)

Resuscitation

A basic method of pulmonary resuscitation withexpired air, using a device portable and simpleenough for emergency use by herdsmen and

Resuscitation 599

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shepherds, is in use on farms The device

con-sists of a mouthpiece, non-return valve, flange,

and mouth tube (See ARTIFICIAL RESPIRATION;

RESPIRATORY STIMULANTS;ACUPUNCTURE.)

Retention of Afterbirth

(see PLACENTA – Retained)

Reticulocytes

The penultimate stage in the formation of red

blood cells Reticulocytes are numerous in the

blood only in anaemic conditions and indicate

an effort of the blood-forming tissues to restore

the red blood cell count to normal levels

Reticulo-Endothelial System

This consists of macrophages, special cells present

in the liver, spleen, lymph nodes and bone

marrow The system has a number of functions

including the regulation of immune responses (see

under ANTIBODY) It also removes disintegrating

red cells from the blood

Reticulum

The 2nd stomach of ruminants

Retina

The innermost layer of the eye; it includes the

light-sensitive rods and cones which transmit

impulses to the optic nerve Detachment of,

or haemorrhage into, the retina is a cause of

sudden blindness in dogs It is often due to

hypertension, the long-term effects of which

may be hypertrophy of the left ventricle of

the heart and kidney failure (See EYEand EYE,

DISEASES AND INJURIES OF.)

Retropharyngeal abscess is the name given to an

abscess occurring at the back of the throat in

the region behind the pharynx Such abscesses

generally make swallowing difficult or

impossi-ble until they burst, which they frequently do

into the cavity of the pharynx, whence the pus

is swallowed (See STRANGLES.)

Retrovirus

A member of the Retroviridiae, the family of

viruses which includes the lentiviruses and

the oncornaviruses Retroviruses are naturally

occurring gene transfer organisms When the

virus infects a cell, it is uncoated; the viral RNA

is transcribed into DNA and this DNA grates into one of the cell’s chromosomes Thisproperty could be used to produce disease-resis-tant transgenic animals Certain viral groupsappear to need the presence of a receptor on the cell membrane in order to gain access intothe cell Retroviruses are enveloped viruses andcarry a glycoprotein on their surface; a specificinteraction with this glycoprotein and the cellular receptor is a prerequisite for infection.Immunodeficiency viruses of humans, cats, cattle and primates are retroviruses

inte-(See table under VIRUSES; also GENETIC NEERING.)

ENGI-Rhabdomyolosis

Rhabdomyolosis, also called azoturia, is a ing down of skeletal muscle in consequence ofwhich the urine contains myoglobin (See EQUINE MYOGLOBINURIA.)

break-Rhabdovirus

A group of bullet-shaped viruses which includesthe rabies virus and that of vesicular stomatitis.Several rhabdoviruses are associated with diseaseconditions in fish

Rhea

Ostrich-like flightless bird, native to SouthAmerica Smaller than ostrich, about 120 cm (4 ft) tall, and has 3 toes

Rheumatism

A general term indicating a painful condition

of muscles, tendons, joints, bones, or nerves; it

is generally less common in animals than inhumans

Rheumatism is seen in dogs, pigs, and horsesmost commonly, but it can affect all of thedomesticated animals Young animals are mostoften attacked by the acute type, especiallyyoung pigs and puppies, and adults by the muscular form and by chronic or particularrheumatism

For the muscular type see under MUSCLES,

DISEASES OF

Treatment There is no absolute specific,although certain drugs have enjoyed a great repu-tation in the alleviation of this disease, especiallysalicylates Phenylbutazone has been used withreported success (See also CORTISONE.)