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

East Coast Fever Theileriosis An acute specific disease of cattle enzootic in certain parts of Africa, especially in the eastern provinces of South Africa, in Kenya and in Zimbabwe.. The

E Coli

Escherichia coli, formerly known as Bacillus coli,

is a normal inhabitant of the alimentary canal

in most mammals This bacterial family is a

large one, comprising many differing serotypes

which can be differentiated in the laboratory

by means of the agglutination test Only a

few serotypes cause disease However, E coli

infections can be severe and have become

suffi-ciently prevalent for a range of vaccines to

be developed for protection against the most

common pathological strains in farm animals

(See also DIARRHOEA; JOINT-ILL; COLIFORM

INFECTIONS.)

Sheep E coli scours and septicaemia are

common in newborn lambs and often fatal

Vaccines are available for protection and

antis-era may be used for treatment

PigsOne serotype gives rise to oedema of the

bowel; another to the death of piglets within a

few days of birth

Those strains of E coli which cause diarrhoea

in piglets only a few days old are able to do so

because they are covered with an adhesive coat

known as the K88 antigen This enables them

to adhere to the wall of the intestine where they

induce disease by means of toxins, causing

diar-rhoea, dehydration, and death

E coli toxins are classified as (a) heat labile

(LT), which may cause severe diarrhoea,

dehy-dration and death of piglets; and (b) heat stable

(ST) associated with only a mild enteritis

Scouring in older pigs may often be caused

by strains of E coli having no K88 antigen.

The K88 antigen and related antigens can

be prepared in the form of a vaccine,

formulat-ed with E coli toxoids This is injectformulat-ed into

pregnant sows and gilts to provide protection

(passive immunity) to the piglets when they

are suckled, via the colostrum, by preventing

the K88-coated E coli from adhering to the

intestinal wall Oral and parenteral vaccines are

available

CattleE coli is an important cause of calf

enteritis, enterotoxaemia and septicaemia, and

of mastitis Combined antiserum preparations,

vaccines, and antisera-vaccine combinations are

available

Poultry Coliform septicaemia is a frequentcause of loss, and one difficult to control sinceinfected birds are disinclined to eat or drink,which hinders drug administration

Dogs E coli is perhaps the most important

pathogen of the bladder and urethra; it alsocauses enteritis

Horse(see FOALS,DISEASES OF)

Public healthA strain of E coli, 0157, has

been associated with outbreaks of disease inhumans Animals that carry this toxic strain donot usually show any signs of clinical disease andshedding of the organism by animals is erratic,making detection difficult Young children andthe elderly are most susceptible to the disease

In the mild form there is blood-tinged rhoea Some of those cases will go on to develophaemorrhagic diarrhoea and a number developneurological disease that is fatal Following anoutbreak involving more than 50 persons whohad eaten contaminated meat, an investigationled by Professor Hugh Pennington of AberdeenUniversity resulted in a series of recommenda-tions for good hygiene practices

diar-Ear

Sound is appreciated through the mechanism ofthe outer, middle, and internal ears Soundwaves are collected by the funnel-like externalear (pinna) and transmitted down into an exter-nal canal, across the bottom of which isstretched the ear-drum or tympanum againstwhich these waves strike Their impact causes avibration of the tympanum, and the soundwave becomes transformed into a wave ofmovement This movement is transmittedthrough a chain of tiny bones, called auditoryossicles, in the middle ear, and then to fluidcontained in canals excavated in the bone of theinternal ear The vibration of this fluid stimu-lates the delicate hair-like nerve-endings whichare found in the membranous walls of thecanals, and impulses pass to the brain, whereby

an animal is able to appreciate external soundsliterally by feeling them

Structure The middle and inner ears areessentially the same in all animals, but theexternal ears present certain differences in dif-ferent species (See also AURAL CARTILAGE.)

External ear

HorsesThe ears serve to some extent as anindication of the state of the horse’s emotions –

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anger or viciousness being shown by laying the

ears flat back against the head, and surprise,

anticipation, or pleasure being indicated by

‘pricking’ the ears At the base of the ear a

com-plete cartilaginous tube is formed, and this

leads into the bony canal or external auditory

meatus

Middle earThe tympanic membrane,

form-ing the ‘drum’, is stretched completely across

the outer passage at its innermost extremity

The cavity of the middle ear is a

compart-ment excavated in the hard mass of the petrous

part of the temporal bone which lodges the

ossicles These are the small auditory bones

which carry impulses across its cavity and are

called the malleus (hammer), incus (anvil), and

stapes (stirrup) The Eustachian tube admits air

from the throat, and so keeps the pressure on

both sides of the tympanum equal

Horses have a diverticulum (guttural pouch)

of the Eustachian tube (See GUTTURAL POUCH

and GUTTURAL POUCH DISEASE.)

Internal earThis consists of a complex

sys-tem of hollows in the substance of the sys-temporal

bone enclosing a membranous duplicate

Between the membrane and the bone is a fluid

known as perilymph, while the membrane is

distended by another collection of fluid known

as endolymph This membranous labyrinth, as

it is called, consists of 2 parts: the posterior

part, comprising a sac, called the utricle and

3 semicircular canals opening at each end into

it, is the part concerned with the preservation

of balance; the anterior part consists of another

small pouch, the saccule, and of a still more

important part, the cochlea, and is the part

concerned in hearing In the cochlea there are 3

tubes, known as the scala tympani, scala media,

and scala vestibuli, placed side by side (the dle one being part of the membranouslabyrinth), which take 21⁄2spiral turns round acentral stem, somewhat after the manner of asnail’s shell In the central one (scala media) isplaced the apparatus known as the organ ofCorti, by which the sound impulses are finallyreceived, and by which they are communicated

mid-to the audimid-tory nerve, which ends in filaments

to the organ of Corti The essential parts of theorgan are a double row of rods and several rows

of cells furnished with hairs of varying length

The act of hearingThe main function ofthe movement of the ears is that of efficientlycollecting sound waves emanating from differ-ent directions, without the necessity of turningthe whole head, although in some animals theears may be flicked to dislodge flies

When sound waves reach the ear-drum, thelatter is alternately pressed in and pulled out;the movements being communicated to theauditory ossicles

These movements are then transferred to theperilymph in the scala tympani, by which inturn the fluid in the scala media is set inmotion Finally these motions reach the delicatefilaments placed in the organ of Corti, and soaffect the nerve of hearing, which conveys thesensations to the auditory centre in the brain

Ear, Diseases of

Diseases of the ears of animals should never beneglected, for although in the early stages mostare amenable to treatment, in the later stagestreatment is likely to be more difficult

Inflammation of the outer ear (otitis externa)may be found in one or both ears It is often due

to the presence of a foreign body (a grasshopper

in one case), parasites or bacterial infection

Ear, Diseases of 209

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Outline of the structure of the ear.

The signs include shaking the head, often

per-sistently for a few moments at a time,

scratch-ing, rubbing head rotation with the affected ear

lowered, and a foul-smelling discharge

Scratching the ears is also a symptom of

ear-mange mite (Otodectes) infection of the external

ear canal (See MITES– Mange in dogs and cats,

for first-aid and treatment of Otodectes.)

Other forms of mange may start at the ears

and involve the pinna, e.g psoroptic mange,

notoedric mange

Discharge from the ear, or the presence of

pus within, is a sequel to a neglected case of

parasitic otitis in the dog and cat and due to

secondary infection by bacteria and/or moulds

Excessive wax in the ear often leads to

disease later It is especially common in dogs

which have large pendulous ear flaps, when

ventilation is poor

In some cases, dressing the inner parts of the

ear is difficult or impossible because of the

thickening and perhaps distortion For these an

operation, in which the cartilages at the lower

parts are opened or resected, has been devised

Operation may also be needed where

deep-seat-ed ulceration of one or other of the aural

carti-lages has occurred, and even the mere initial

cleaning of a very inflamed and painful ear

must be done under an anaesthetic

Foreign bodies, such as hay seeds, sand,

pieces of glass, wood, peas, or parasites, may

become lodged in the ears of animals and give

rise to irritation occurring very suddenly

Haematomais common in dogs and in cats

which are affected with ear mange, but it may

occur in almost any animal A large fluctuating

swelling appears upon the flap of the ear and

causes the animal to hang its head towards the

same side In many cases little or no pain is

experienced once the swelling has appeared,

and, in fact, a small swelling becomes larger in

many cases through the continued shaking of

the head even after its original formation The

swelling is caused by bruising of the skin and the

blood vessels which lie between it and the

carti-lage, with a consequent extravasation of blood

or serum under the skin The condition is

treat-ed by opening the haematoma under conditions

of surgical cleanliness, evacuating the fluid

contents, and suturing the skin in such a way

that the collection of more fluid is prevented

Woundsof the flaps of the ears are usually

caused by bites, or from barbed wire, etc., in the

larger animals The comparatively poor blood

supply to the AURAL CARTILAGESmeans that,

if torn or lacerated, necrosis may occur In dogs

it may be necessary to secure the ear-flaps bymeans of surgical adhesive tape, or a head-cap improvised to give several ‘tails’ which can

be tied

Deafness(see under this heading)

Middle-ear infection (otitis media) isalways serious as it may lead to MENINGITIS It

is often found on one side but both ears may beaffected Signs are similar to those of externalear inflammation but the balance can be affect-ed; there is swaying of the hind quarters and the head is carried abnormally It may be caused

by spread of external ear infection or by aninfection carried in the blood

Inner-ear infection (otitis interna): signsare – the head is often rotated; the animal maywalk in circles and show a stumbling, swayinggait

Tumours are occasionally found Warts arenot uncommon in horses and cattle In cats apolyp is occasionally found, and in white cats asquamous-celled carcinoma may affect the tip

of the pinna

MangePsoroptic and notoedric mange oftenbegin on the pinna of the ear; auricular orotodectic mange involves the presence of mites

(Otodectes) within the ear canal (See MITES.)

Fly strike A dog brought to a veterinary surgeon in Cornwall was found to have a badlyinfected left ear, from which came a profusepurulent discharge On auroscopic examina-tion, Mr D S Penny BVetMed was surprised tosee three faces staring back at him Underanaesthesia 18 large maggots were removed

Ear Tags

A permanent method of identifying animals It

is the main method of legal identification ofcattle Tags are also used in sheep, goats andpigs as well as other animals They can incorpo-rate an insecticide (see FLIES)

Ear Tipping

Ear tipping of feral cats has been advocated byanimal welfare organisations and practised inAmerica and Denmark, for example The idea

is to identify those cats which have been spayed,and prevent any ‘rescued’ cat from being subjected to unnecessary anaesthesia andlaparotomy

210 Ear Tags

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In Australia, ear tattooing is practised for

the same purpose, but has the disadvantage that

the spayed feral cat cannot be identified from a

distance

Early Weaning

(see under WEANING)

Ears as Food

Ears from beef cattle which had been receiving

sex hormones as implants in the ear have been

fed in breeding kennels with disastrous results

Earthing

Earthing of electrical apparatus on farms, and

especially in the dairy, is occasionally faultily

car-ried out in such a way that in the event of a

short-circuit, the water-pipes supplying the cows’

drinking-bowls become ‘live’ – leading to the

electrocution of the cows (See ELECTRIC SHOCK.)

Earthworms

Earthworms are of veterinary interest in that

they act as intermediate hosts to stages in the

life-history of the gape-worm of poultry (see

GAPES) and of lung-worm in pigs They may

also harbour viruses which cause disease in pigs

Earthworms can live for as long as 10 years

They can often be found at night in drains

out-side piggeries, and in crevices and cracks in the

cement inside piggeries (See also INFLUENZA.)

An ARC research team at the Rothamsted

Experimental Station found that earthworms,

bred in animal manure, can provide a

high-quality protein supplement for pigs, poultry,

and especially fish Several species of earthworm

were used, of which Lumbricus rubellus was the

one of choice Eisenia foetida (the brandling

worm) is easier to farm but contains a

heat-labile toxin in its skin making it unsuitable as a

raw food Ideally, earthworms should be

heat-processed into meal for use in animal diets

East Coast Fever (Theileriosis)

An acute specific disease of cattle enzootic in

certain parts of Africa, especially in the eastern

provinces of South Africa, in Kenya and in

Zimbabwe In these areas the native cattle

attain a certain amount of natural immunity,

and only imported animals are affected

Animals which recover are commonly known as

‘salted’, but the mortality is very high (e.g 90

per cent) in new outbreaks of the disease

Buffaloes are also susceptible

Cause Theileria parva, which spends part of

its life-history in cattle and part in ticks

(Rhipicephalus appendiculatus).

SignsAfter an incubation period of a fortnight

or so, the animal becomes dull, listless, losesappetite, and runs a high fever Lymph nodesbecome enlarged There may be a dischargefrom eyes and nose; laboured breathing anddiarrhoea may be seen

Prevention and treatment East Coastfever may be to a great extent prevented by systematic dipping of all newly purchased cattle, and quarantining them for at least

5 weeks before they are mixed with the rest ofthe stock

Where the disease has broken out on a farm,the ‘short-interval’ dipping system first devised

by Watkins-Pitchford has proved of immensebenefit in eradicating it (See under CONTROL OF TICKS.)

Since ticks responsible for the spread of EastCoast fever can live for some time on otherdomesticated animals, it is advisable to dipsheep, goats, and horses at suitable intervals.Clinically ill cattle may be treated by anyantibiotics that can penetrate cell membranes,such as tetracyclines

East Friesland Milk Sheep

This breed comes from NW Germany, and

in England has been used to produce the BRED East Friesland ewes average 545 litres(120 gallons) at 6 per cent butterfat in a lacta-tion, rearing their lambs, and a yield of 1000litres (220 gallons) is not unknown The lambshave a high growth rate and early maturity

COL-‘Eastrip Special Blend’

A cross between Bluefaced Leicester and PollDorset sheep A high lambing percentage isclaimed

350 died (See underMONKEYS,DISEASES OF.)

An outbreak of disease caused by an related filovirus, and by simian haemorrhagicfever, occurred in 1990 at an American quaran-tine station among cynomolgus monkeysimported from the Philippines It was reportedthat this was the first case in which a filovirushad been isolated from non-human primateswithout deliberate infection

Ebola-Ebola Virus 211

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Ecbolics are drugs which cause contraction of

the muscle fibres of the uterus, such as ergot,

pituitrin, etc They are used to induce labour

Ecdysis

Ecdysis is the shedding of an exoskeleton in

arthropods, and of the old skin in crustacea and

reptiles Failure to shed completely can lead to

problems

Echinococcosis

(see HYDATID DISEASE;TAPEWORMS)

Echium Plantagineum

A poisonous plant, also known as Paterson’s

Curse, or Salvation Jane, which has caused the

death of many sheep from copper poisoning in

South Australia In one outbreak, 1259 sheep

died out of a total of 29,715 at risk On one

farm, 500 of 3000 ewes died Merino ×Border

Leicester crosses appear to be especially

suscep-tible At autopsy, jaundice is evident; livers are

friable and enlarged or, less frequently,

shrunk-en and fibrotic Kidneys are swollshrunk-en, soft and

blackish

The plant contains up to 10 alkaloids, and is

the first to show growth after a prolonged

drought

Eclampsia

Eclampsia is a disease occurring during the later

stages of pregnancy or after parturition, and

characterised by loss of consciousness or

con-vulsions, or both It occurs in the bitch and

cat A preferable name is lactation tetany It is

associated with HYPOCALCAEMIA (See also MILK

FEVER;FITS.)

Ecraseur

A surgical instrument used for castration of the

larger domestic animals Haemorrhage is

large-ly prevented by crushing of the blood vessels of

the spermatic cord

Ecthyma

Ecthyma is a localised inflammation of the

skin characterised by the formation of pustules

(See ACNE;IMPETIGO.)

Ectropion

Ectropion is a condition of the eyelids, in whichthe skin is so contracted as to turn the mucousmembrane lining of the lid to the outside

Eczema

An inflammation of the skin (dermatitis),occurring in both farm and domestic animals.Intense irritation or itchiness may accompanythe acute form, and frantic licking of the affect-

ed area may exacerbate the condition In

chron-ic eczema there may be very little irritation

CatsEczema is often referred to as feline miliarydermatitis Symptoms include reddening of theskin, with the appearance of papules (small blister-like spots) and, later, scabs These may be easier to feel than to see The area of skininvolved may be small or large Neck, shoulders,and back are common eczema sites Occasionally

a bacterial infection is a complication

The most common cause is considered to

be hypersensitivity to flea bites Once a cat (seldom a young one) has become sensitised toflea saliva, the presence of only a single flea onthe cat’s body is sufficient to cause the allergicreaction

Other allergies may produce eczema; forexample, a ‘hay-fever’ type (see ATOPIC DISEASE),

or a food allergy of some kind Cat foods containing colouring agents or preservatives are

212 EC

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sometimes involved Skin contact with some

chemicals should also be considered It is likely

that among some breeds or strains there is a

family predisposition to eczema

Treatmentinvolves flea removal; the

veterinar-ian may prescribe a change of diet, a vitamin

sup-plement, megestrol acetate, an antihistamine, etc

DogsThe causes, symptoms and treatment of

eczema are similar to those described above The

disease is more common in dogs, however, and

an acute form often involves the skin between

the toes, resulting in constant licking Other

sites are around the eyes, and the scrotum

First-AidCalamine lotion may be applied if

precautions can be taken to prevent its being

immediately licked off

In a few cases what a dog-owner assumes to

be eczema may prove to be mange; a

profes-sional diagnosis should always be obtained

HorsesA common cause of eczema is

sensiti-sation to midge-bites (See ‘SWEET ITCH’ for

preventive measures.)

Cattle and sheep Some cases of eczema

affecting white-haired areas of skin are the

result of LIGHT SENSITISATION Overseas this

condition is often referred to as ‘facial eczema’

and follows sensitisation to sunlight following

the eating of certain plants

Edema

Edema is another spelling of oedema

Edta

Ethylenediamine tetra-acetic acid Its salts

(ede-tates) are chelating agents which are used to

treat poisoning by heavy metals For example,

calcium edetate is used in cases of lead

poison-ing Non-clinically, sodium edetate is used as an

anticoagulant for blood samples

Efferent

Efferent is the term applied to vessels which

convey away blood or a secretion from a part, or

of nerves which carry nerve impulses outwards

from the nerve-centres

Effluent

Liquid waste from an abattoir or slurry (see

SLURRY;DAIRY HERD MANAGEMENT)

Egg-Bound

Egg-bound is the condition in laying poultry in

which an egg (or eggs) may be formed in the

oviduct, but the hen is unable to discharge it.The bird shows obvious discomfort, standsstraining and pressing A dose of liquid paraffin(2 ml) may be tried

Egg Eating

Among intensively housed poultry, this may be

a vice or sign either of boredom or of pain

Egg Yield

In Britain, the average is approximately 130eggs per bird per year An annual yield of 200 isobtained in well-managed batteries; about 190

on deep litter; 170 in fold units A Honeggerhas laid 305 in 350 days

Ehrlichiosis

Infection with species of Ehrlichia, a rickettsia.

E risticii is one cause of abortion in mares

E chaffeensis is a cause of human ehrlichiosis.

Canine ehrlichiosis has as its vector the browndog tick (See TICK-BORNE FEVER OF CATTLE.)

Eicosanoids

Arachidonic acid, a polyunsaturated fatty acid present in most body cells of domestic ani-mals, can be oxidised to the prostaglandins,prostacyclin, thromboxanes and leukotrienes.These compounds, collectively known as theeicosanoids, are involved in inflammatory andallergic conditions; in reproductive and perina-tal processes; with platelet aggregation and vascular homeostasis, kidney function, fever,and certain tumours; and with other normaland disease conditions

cole in the brain; and E rangiferi in the muscles

and central nervous system

Elastic Bands

(see RUBBER BANDS)

Elastic Bands 213

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An instrument used to stretch a strong rubber

ring so that it may be placed over the neck of

the scrotum for the purpose of castration

Elbow

Elbow is the joint formed between the lower

end of the humerus and the upper ends of the

radius and ulna

Electric Fences

(see under PASTURE MANAGEMENT)

Electric Shock, ‘Stray Voltage’

and Electrocution

Faulty electrical wiring and earthing have led to

drinking-bowls, water pipes, mangers, etc

becoming live In some instances this has led to

the death of cows from electrocution following

a short circuit

‘Stray voltage’In one incident this led to

cows refusing concentrates in the parlour – not

because they were unpalatable, as at first

thought, but because cows wanting to eat were

deterred by a mild electric shock

This ‘stray voltage’ has been associated with

intermittent or unexplained periods of poor

performance, increased milking time, and ‘an

increased prevalence of mastitis’ ‘Stray voltage’

was detected in 32 out of 59 dairy farms in

Michigan, following investigations requested by

dairymen or veterinarians

Electrocution Deaths from electrocution

may occur outside buildings In one case 30

cows and heifers were found dead beneath an

electric pylon It seems that the cattle had used

a metal stay as a rubbing ‘post’, which had

become loose and then come in contact

with the high-voltage lines that the pylon was

carrying

PigsMetal troughs becoming electrically live

led to 20 pigs becoming paralysed after a severe

thunderstorm in England Injuries apparently

resulted from panic and crushing In another

case 22 out of 32 pigs in one pen were found

piled up around the trough, close to which was

a burnt-out live wire The carcases were bloated

and the skin bluish Additional post-mortem

findings may include external burns, numerous

haemorrhages affecting many internal organs,

black unclotted blood, congestion/oedema of

the nervous system, and fracture of lumbar

ver-tebrae or of the pelvis In pigs, rupture of the

urinary bladder may occur

HorsesA New York insurance agency has

stat-ed that 0.96 per cent of its claims in respect ofthe death of horses were for lightning strike,and 0.27 per cent for electrocution

In Canada a veterinarian was asked to call tosee a horse which appeared to be suffering fromcolic On arrival at the farm he was told that theanimal had died minutes after he had been telephoned Earlier the same day, the ownerexplained, a mare in foal had died instantly inthe same spot in front of a small barn; andanother had died there too Suspecting electro-cution, she had switched off the barn’s powersupply

Subsequently an inspector found that thebuilder of the barn had made a serious mistakewhen carrying out the electrical work, so thatwhat was supposed to be the earth line was any-thing but safe The situation had become moredangerous after recent excavation in front of the barn, where the earthing plate had beenaccidentally dug up and replaced horizontallyacross the path to the barn The horses had died

on the first wet day after the work was pleted; but their owner recalled that previous tothat they had shied or tended to bolt whenpassing the spot

com-Dogs and catsElectrocution is not mon, and almost invariably results from pup-pies or kittens chewing through the insulation

uncom-of electric wiring (e.g uncom-of vacuum-cleaner, lamp, etc.) Burns to the mouth and lips areseen; a tan to grey discoloration is noticeable.Oedema of the lungs may be caused, with dys-pnoea In a survey of 26 dogs treated for elec-trocution, 16 survived and were dischargedfrom hospital within 2 or 3 days Mortality ratefor all the dogs in the survey was 38 per cent.(See EUTHANASIA.)

table-Lightning strike Cattle, sheep, and horsesare most often affected Usually death occursinstantly, and the animal is often found with

a bunch of grass between its teeth Usually, but not invariably, there are external scorchmarks, with subcutaneous lesions beneath Theother signs are as those given above under

‘Electrocution’

Static electricity can build up on ment made from materials such as plastics Inone incident, turkeys refused to eat because of

equip-a build-up of stequip-atic electricity on the chequip-ain feeders which gave the birds a shock when they attempted to feed The situation wasdetected when it was noticed that wood shav-ings were attracted to the feeders where the

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chains were operated Earthing the feeders

removed the problem

Electrocardiogram (ECG)

Electrocardiogram (ECG) is a record of the

variations in electric potential which occur in

the heart as it contracts and relaxes This record

is obtained by placing electrodes on either

side of the chest wall or on the two forelegs,

the skin being first wetted with salt solution

These are then connected to an

electrocardio-graph, which records the pattern of the heart’s

activity The normal electrocardiogram of each

heartbeat shows 1 wave corresponding to the

activity of the auricle, and 4 waves

correspond-ing to the phases of each ventricular beat

Various readily recognisable changes are seen

in cases in which the heart is acting in an

abnor-mal manner, or in which one or other side of

the heart is hypertrophied This record,

there-fore, forms a useful aid in many cases of cardiac

disease

Electrocardiography has been described

as a useful aid to pregnancy diagnosis in the

mare – ‘where thoroughbred mares more than

5 months pregnant are presented for sale’ (see

under TWINS); and also for monitoring heart rate

during anaesthesia

Electrocautery

Electrocautery is useful for operations where

space is restricted, such as removing small

tumours, etc in mouth, nose, or throat, and

to check haemorrhage in the deeper parts of

wounds Also sometimes for disbudding (See

also CRYOSURGERY.)

Electrocution

(see under ELECTRIC SHOCK)

Electrolyte

Any compound which, in solution, conducts an

electric current and is decomposed by it (See

under FLUID REPLACEMENT THERAPY;NORMAL

SALINE;DEHYDRATION.)

Electrolyte Solutions

Electrolyte solutions contain sodium,

potassi-um and other electrolytes in an ISOTONIC

for-mulation They are used, often with plasma

substitutes or other additives, in restoring the

body fluid volume in cases of shock, diarrhoea,

injury and other conditions

Electron Microscope

These instruments have made it possible to

study and photograph viruses, bacter-iophages,

and the structure of bacteria Instead of light,the electron microscope uses a beam of electrons

to scan the specimen This is prepared as anextremely thin film and subjected to a highdegree of vacuum The electron image is focused

on a video screen and may be recorded graphically or electronically Magnification may be up to ×300,000, and by means of photographic enlargement and the use of pro-jection slides a total magnification approaching

photo-×1,000,000 can be achieved

Electrophoresis

The movement of particles in a fluid under theinfluence of an elecric current It is used, e.g., inthe analysis of blood or serum constituentswhich form visibly identifiable patterns in astarch gel to which current is applied

ElectrotherapyHigh-frequency currentsare mainly used

to produce muscular contractions as an aid tomuscular re-education following injury or during transient paralysis It can also be usedfor passive exercise when an animal is sufferingfrom certain neurological conditions The tech-nique is painless and no control measures are necessary Animals must not, however, beexcited during periods of therapy, which varybetween 5 and 20 minutes per day Somechronic skin conditions may be controlled bythis method Where movement of painful joints

or tendons is required, or where there is tis, administration of painkillers or use of nerveblocks by local anaesthetic may be considered

neuri-Diathermy is a modified form of

high-frequency current therapy in which warmth isinduced deep in the tissues

Repetitive stimulation is produced by cardiac

pacemakers; these have been used in small animals and in horses

Faradism is the use of electric currents to treat

certain muscle, tendon and joint conditions,mainly in horses It has also been used in workingelephants

(See also X-RAYS; IONIC MEDICATION; TOPHORESIS;CANCER.)

of belladonna, potassium chlorate, and aniseed,made up into a paste with treacle, was formerlymuch used The electuary is applied by means

Electuary 215

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of a flat stick, and is smeared upon the back of

the tongue and upon the teeth

Elephants

(see MUSTH;SPEED OF ANIMALS) The height to

the shoulder of the Asian elephant (Elephas

maximus) is about 3 metres (10 feet); that of the

African elephant (Loxodonta africana) 3.5

metres (131⁄2feet)

Elephants, Diseases of

These include anthrax (sometimes brought on

by the breaking of a tusk where the disease has

lain dormant in the dental pulp), multiple

abscesses, blackleg, botulism, elephant pox,

enzootic pneumonia, foot-and-mouth disease,

influenza, myiasis, parasitic gastroenteritis,

pas-teurellosis, rabies, salmonellosis, steanofilarial

dermatitis, schistosomiasis, surra, tetanus,

try-panosomiasis, tuberculosis Elephants imported

into Great Britain may serve out their

quaran-tine period for foot-and-mouth disease on

board the ship transporting them

ELISA

ELISA is the abbreviation for the system of

enzyme-linked immunosorbent assay,

devel-oped by the Swedish scientists Engvall and

Perlmann ELISA tests are widely used in

labo-ratories for the rapid detection of pathogens

Elizabethan Collar

Often improvised from cardboard, the shape

of a lampshade, and designed to fit over the

dog’s head and to be attached to its collar,

with the object of preventing the animal from

interfering with wounds, skin lesions or ings The illustration shows a proprietary version

dress-Elk

A species of large deer also called the wapiti

(Cervis elaphus); the European elk is Alces alces; the American moose A americana This farmed

animal was found to be a source of tuberculosis

in people in Alberta, Canada, in 1990

Mycobacterium bovis was isolated.

Elkhound

A medium-sized dog with thick grey-black coat, pointed ears and a bushy tail curled over the back; it originated in Scandinavia.Inherited traits include progressive retinal atrophy, renal cortical hypoplasia and hip dysplasia

blood-THROMBOSIS;CATHETER EMBOLUS.)

tech-216 Elephants

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This Elizabethan collar is a transparent version,

easy to adjust to the dog’s neck diameter An

excellent way of preventing the canine patient

from interfering with wounds, skin lesions, or

dressings.

gonadotrophins to cause superovulation, the

production of multiple eggs and therefore

mul-tiple embryos The embryos are collected and

transferred surgically, or non-surgically by a

method similar to artificial insemination, to the

recipient cow which must be at exactly the same

stage of oestrus as the donor Embryos may be

preserved by deep-freezing and thawed for use

when required

A number of firms operate commercial

embryo transfer services; success rates of up to

70 per cent are achieved

Embryo transfer is also used in sheep and

goats; it is possible, but little used in practice, in

mares and pigs (See illustration on page 162.)

The advantages of embryo transfer have been

summarised as follows: (1) increased number

of offspring from valuable females; (2) rapid

progeny testing of females; (3) induction of

twinning; (4) the investigation of causes of

infertility; (5) transport of cattle ova from one

state or country to another; and (6) an

increased rate of genetic improvement

DevelopmentThe technique had already in

the 1950s been successfully carried out in sheep

– ewes having produced young of which they

were not, in the full sense, the mothers; and it

was extended to cattle later, by L E Rowson

and colleagues at Cambridge, who were

respon-sible for much of the research

Development of a method of freezing theembryos greatly widened the scope of embryotransfer Fertilised 10- to-13-day eggs (blasto-cysts) are treated with a protective agent(dimethylsulphoxide) to prevent damage byfreezing and cooled to –196°C; they are thenstored in liquid nitrogen until required forimplantation

The techniqueFive days before oestrus is due,the donor animal is treated with pregnant mare’sserum gonadotrophin (PMSG) or a similargonadotrophin to produce superovulation Whenoestrus occurs, insemination is carried out 2 or 3times, using fresh rather than frozen semen

Surgical transferOn day 6, when the eggsare at the morula stage, consisting of 8 to 32cells each, and looking under the microscopelike blackberries, they are flushed out of theFallopian tube This may be done surgically ornonsurgically In the former, a fine catheter isinserted through a blunt needle after surgicalexposure of the uterus by means of a flank inci-sion, the cow being under local anaesthesia Itmay be possible to recover 8 to 12 ova, and anattempt is made to select the normal ones (Forexample, by culturing them for 1 or 2 days afterrecovery In that time further development willhave occurred; eggs which do not show this arediscarded.) The transfer is made by puncturing

Transplantation As a 7-day embryo, this calf was stored for a month at a temperature

of –196°C before being transferred, non-surgically, to the recipient cow seen in the

Embryo Transfer 217

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one horn of the anaesthetised recipient’s uterus

with a small pipette containing one ovum in a

synthetic medium This liquid is forced out of

the pipette, carrying the ovum with it

Non-surgical transferThe eggs are collected

by means of a 2- or 3-way catheter having an

inflatable cuff The catheter is passed through the

cervix and into one of the horns of the uterus

which is then sealed by inflating the cuff Fluid is

flushed into the horn and withdrawn through

the catheter, with the eggs The technique for

transfer into the recipient cow is similar to

artifi-cial insemination An egg is placed into a ‘straw’

and the embryo introduced into the uterine horn

by means of an insemination ‘gun’ With skilled

operators, the results by this method are

compa-rable with surgical collection and without the

trauma of a surgical operation This method is

commonly used in the dairy industry

The first inter-species transfer of embryos was

carried out in 1979 at the Thoroughbred

Breeders’ Association’s equine fertility unit at

Cambridge This resulted in a pony mare foaling

a donkey (gestation period about 346 days or

about 15 days longer than for a foal), and 2

don-keys giving birth to pony foals (born after 346

and 361 days’ gestation period, respectively)

(See PLACENTA.)

Embryology

Embryology is the study of the development of

the embryo within the body of the female

Embryotomy

The section and removal of a fetus in the uterus

to facilitate parturition; most commonly taken in cattle and sheep

Destructive (vesicular) emphysemais

a condition of the lung characterised by anabnormal enlargement of the air spaces, accom-panied by destructive changes in the alveolarwall This condition occurs in dogs with chron-

ic bronchitis and in horses with chronic tive pulmonary disease (see ‘BROKEN WIND’).Emphysema is irreversible and may progress torespiratory failure and death The main symp-tom is respiratory distress on exertion, with amarked expiratory effort

obstruc-Interstitial emphysema Air is present inthe connective tissue of the lung – a state of

218 Embryology

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Twins from different mothers One of 2 eggs was removed from the Border Leicester ewe and transplanted into the Welsh ewe.

inflation of the interstitial (interlobular) tissue.

The air is found in the lymphatics, under the

pleura in the interlobular septa, and around

blood vessels, sometimes in the form of large

bullae 10 cm or more in diameter Air may track

as far as the hilum of the lung and gain access

to the mediastinum from where, in exceptional

circumstances, it may even spread to

subcuta-neous connective tissue – usually in the shoulder

region or over the upper part of the chest

Interstitial emphysema is a common

condi-tion in cattle, especially in associacondi-tion with

par-asitic bronchitis (HUSK) or with ‘FOG FEVER’

Increased effort, in response to obstructed

airways, over-exertion and violent struggling,

causes a marked increase in pressure within the

alveoli Rupture then occurs, allowing air to

escape into the interstitial tissue on inspiration,

but impeding its leaving on expiration When

the lung lobules become surrounded by

inter-stitial emphysema their ability to inflate during

inspiration is restricted, and this may lead to

respiratory distress

Empyema

A collection of purulent fluid within a cavity

(See PYOTHORAX;PLEURISY.)

Emu

A large flightless bird, Dromaius

novae-hollandiae, native to Australia It is farmed in

Britain but to a lesser extent than the ostrich

Severe enteritis resulting in death of up to 65

per cent of a flock has occurred in the USA

from infection by eastern equine encephalitis

virus This is a NOTIFIABLE DISEASEthroughout

the EU

Enamel

The very hard substance found on the external

surface of the crowns of teeth (see TEETH)

Enarthrodial Joints

Enarthrodial joints are those of the

ball-and-socket type which allow movement in nearly

any direction Examples include the shoulder

joint between the scapula and the humerus; and

the hip joint in which the nearly spherical head

of the femur fits into the cup-shaped cavity

called the acetabulum on the pelvis

Encephalitis

Encephalitis is inflammation of the brain It

may be brought about through the activity of

bacteria, such as those of strangles and

listerio-sis, but especially during infection with viruses,

such as those of rabies, canine distemper, etc

(See BOVINE SPONGIFORM ENCEPHALITIS.)

SignsSymptoms of encephalitis include fever,excitement, delirium, convulsions, paralysis,and loss of consciousness Several symptoms are common to MENINGITIS (See also SLEEPER SYNDROME.)

First-AidKeep the animal quiet – in a ened room if showing excitement – and avoidnoise or handling the patient

dark-Encephalitozoon Cuniculi

An intracellular protozoal parasite It develops

in macrophages, brain, kidney and other tissues

of rabbits, dogs, rodents and primates

In carnivores, severe nephritis, encephalitisand a high mortality are associated withtransplacental infection

In a Norwegian outbreak, 1500 blue fox cubsdied (33 per cent of the litters), although theparents showed no signs of infection

In the UK, foxhound puppies have died, and

in Tanzania 2 spaniel puppies died which hadshown rabies-like signs

DiagnosisAn ELISA test In one study, 51positive samples were identified out of 248 serafrom stray dogs

of pigs Another example of encephalomalacia

is ‘crazy chick’ disease

Encephalomyelitis

Inflammation of both the brain and the spinalcord

Encephalomyelitis, Viral, of Pigs

This term covers the group of diseases known as

Teschen disease, Talfan disease, and Poliomyelitis

suum.

Believed to have originated in the formerCzechoslovakia, viral encephalomyelitis of pigs

is now encountered throughout most of Europe

In Britain and Denmark, only a small age of pigs become infected, and illness is farmilder than in some other countries

percent-Symptoms include fever, stiffness, staggeringgait, paralysis, and those of encephalitis

Encephalomyocarditis Virus

Encephalomyocarditis virus is a picornavirus.Antibodies have been found in the serum ofmore than 28 per cent of normal pigs in the

Encephalomyocarditis Virus 219

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UK It is also a pathogen of rodents and human

beings, and has caused outbreaks of illness in

pigs in Australia, the USA, and Panama

Enchondroma

A tumour formed of cartilage (See TUMOURS.)

Encysted

Enclosed in a cyst

Endangered Species Act 1982

Endangered Species Act 1982 lists measures for

the protection of named animals

Endarteritis

Inflammation of the inner coat of an artery (See

ARTERIES,DISEASES OF.)

Endemic

An endemic disease is one present in an animal

population at all times

Endo-Endo- is a prefix meaning situated inside

Endocarditis

Inflammation of the smooth membrane that

lines the inside of the heart It occurs especially

over the heart valves (See HEART DISEASES.)

Endocrine Glands

Endocrine glands are those which secrete

hor-mones (See HORMONES; also under the name of

individual endocrine glands, e.g ADRENAL,

THYROID, PARATHYROID, PITUITARY, THYMUS,

PANCREAS.)

Endometritis

Inflammation of the mucosal lining of the uterus

(endometrium) (see UTERUS,DISEASES OF)

Endorphins

Morphine-like, natural analgesics produced in

the body Acupuncture is said to stimulate their

release into the bloodstream (See also TWITCH.)

Endoscope

An instrument used for viewing the interior of

an organ, and for facilitating the extraction of a

foreign body, e.g from the oesophagus; and for

assistance with other surgery, including embryo

transfer (See also LAPAROSCOPY.)

Endothelium

Endothelium is the membrane lining various

vessels and cavities of the body, such as the

pleura, pericardium, peritoneum, lymphatic

vessels, blood vessels, and joints It consists of a

fibrous layer covered with thin flat cells, whichrender the surface perfectly smooth and secretethe fluid for its lubrication

Endotoxins

Endotoxins are those toxins which are retainedwithin the bodies of bacteria until the latter dieand disintegrate

English Springer Spaniel

Long-eared, medium-sized dog with silky coat,brown and white or black and white; originallybred as a gun dog Retinal dysplasia, entropion,cutaneous asthenia and haemophilia may beinherited conditions

Enrofloxacin

Enrofloxacin is a quinolone antibacterial activeagainst a wide range of Gram-positive andGram-negative organisms As it may affect thedevelopment of load-bearing articular cartilage,

it should not be administered to growing animals

CauseA plant, common on wet land, known

as duraznillo blanco (Solanum melacoxylon or

glaucum) Poisoning may arise from deliberate

eating of the leaves or from the accidental

220 Enchondroma

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consumption of dead, fallen leaves during

grazing of the underlying pasture plants It is

particularly dangerous when growing in

associ-ation with white clover

It produces an arteriosclerosis, with

calcifica-tion in heart, aorta, lungs, etc Blood levels of

calcium and phosphorus tend to be high as

S malacoxylon contains a potent metabolite of

vitamin D

Signs Emaciation occurring over weeks or

months, and an abnormal gait

Enteralgia

Enteralgia is another name for colic

Enteritis

Inflammation of the intestines (see DIARRHOEA

and INTESTINES,DISEASES OF)

Enterocele

(see HERNIA)

Enteroliths

Enteroliths are stones that develop in the

intestines, being formed by deposition of

salts round a hard metallic or other nucleus (See

CALCULI.)

Enterostomy

Enterostomy means an operation by which an

artificial opening is formed into the intestine

Enterotoxaemia

An acute disease of calves, lambs, goats, and

occasionally of piglets and foals

CauseToxins emanating from the intestines

and present in the bloodstream The toxins

involved are from 4 strains of Clostridium

welchii and from some strains of E coli.

SignsSevere enteritis, with dysentery in some

cases, and sudden death in others

PreventionA vaccine is available

Calves seldom survive for more than a few

hours

Goats show a sudden drop in milk yield,

dysentery, and death within 36 hours There is

also a subacute type of the disease lasting 7 to

10 days, and followed by recovery

Sheep The disease affects both unweaned

lambs and sheep 1 to 2 years old

Enteroviruses

A group of smaller viruses pathogenic to mals and causing disease in cattle, pigs andducks (duck hepatitis)

MANAGE-VENTILATION;CALF HOUSING)

(epidemic), in which a disease spreads rapidlythrough large numbers of animals over a widearea

For enzootic abortion of sheep, see under ABORTION,ENZOOTIC

Enzootic Bovine Leukosis

(see BOVINE LEUKOSIS)

Enzootic Haematuria

A disease typically found in old suckler cows lowing the long-term ingestion of bracken Itresults in various cancer problems of the bladder

fol-Enzootic Muscular Dystrophy

A disease in calves, lambs and foals caused byvitamin E and selenium deficiency Acute casesmay drop dead after exercise; mild cases areweak and breathe with difficulty

Enzootic Ovine Abortion

Enzootic ovine abortion is caused by Chlamydia

psittaci (See under ABORTION,ENZOOTIC.)

Enzootic Nasal Granuloma

Obstruction of the nasal cavities of cattle by aneosinophilic granuloma More common inChannel Island breeds

Enzootic Pneumonia of Calves

Acute pneumonia usually seen in calvesbetween 2 and 4 months old; it is caused

Enzootic Pneumonia of Calves 221

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by environmental and management changes

as well as viral, mycoplasmal and bacterial

infections

Enzootic Pneumonia of Pigs

This was formerly described as virus pneumonia

of pigs (VPP), but the cause is now generally

regarded as being Mycoplasma hyopneumoniae.

However, other organisms may be involved to a

varying degree (See RESPIRATORY INFECTIONS

OF THE PIG;SYNERGISM.)

Many pigs reaching the bacon factories are

affected with some degree of pneumonia, so

that the matter is of the very greatest economic

importance

SignsWhen the disease is first introduced into

a herd, pigs of all ages (from 10 days upwards) go

down with it, and many die Where the disease

is already present, deaths are few Symptoms,

which may easily be overlooked or ignored, then

consist merely of a cough There is, in addition,

a certain degree of unthriftiness which in

extreme cases may amount to stunted growth In

all cases one may expect the liveweight gain to be

reduced Sometimes pigs which contract the

dis-ease earlier in life quite suddenly develop acute

pneumonia at 19 to 26 weeks of age, known as

‘secondary breakdown’ Affected animals lose

their appetite and often become prostrate,

breathing rapidly with a temperature over

40.5°C (105°F) A number die if left untreated,

but the majority have a fluctuating fever for a

few days and then recover

PreventionVaccination at 1 to 10 weeks of

age and management measures such as avoiding

buying-in infected stock Litters are best kept in

arks on pasture, and any sows showing a cough

eliminated Weaned pigs should not be brought

into a fattening house where pigs with

pneu-monia are present (See DUSTY ATMOSPHERE;

SWINE INFLUENZA.)

Diagnosis Confirmed by a complement

fixation test

Treatment Macrolide antibiotics,

adminis-tered on a herd or individual basis, help to

control the severity of outbreaks

Enzootic Pneumonia of Sheep

(see PASTEURELLOSIS;PNEUMONIA OF SHEEP)

Enzymes

Enzymes are complex organic chemical

com-pounds which facilitate or speed biochemical

processes in the animal body, including those of

digestion Some enzymes are also produced bythe normal bacterial inhabitants of the intesti-nal canal Each has a specific use in splitting upproteins, carbohydrates, fats, or crude fibre.The best known are the ptyalin of saliva anddiastase of the pancreatic juice, which breakdown starches into soluble sugars; pepsin fromthe gastric juice and trypsin from the pancreas,which break complex proteins into simpleamino acids; and lipase in the intestines, whichattacks fats (See DIGESTION.) Enzymes are used

in the cleaning of badly infected wounds (See STREPTODORNASE.)

Some enzymes detoxify poisons, breakingthem down into relatively harmless compounds.The differing susceptibility of cat and dog, forexample, to phenol is due to the former animallacking a particular enzyme which the dog has.(See TAURINE.)

Some enzymes are injurious (see under THIAMIN)

(See also BLOOD ENZYMES, and CREATINE KINASEfor enzymes used in diagnosis.)

Eosinophil

Eosinophil is the name given to white cells inthe bloodstream containing granules whichreadily stain with eosin, a histological dye The nucleus of this leukocyte is lobular.Eosinophils, basophils, and neutrophils are collectively known as polymorphonuclearleukocytes As well as these circulating cells,eosinophils are found in the pituitary andpineal glands

In a normal horse, 2.5 ml3(1 cu in) of bloodcontains between 5 and 8 million eosinophilwhite cells – compared with about 160 millionother white cells, and 128,000 million red cells.Eosinophils increase in numbers during certain chronic infections and infestations withparasites They contain hydrolytic enzymes

‘Unlike neutrophils, eosinophils have lowphagocytic capacity and are not good at killing

microorganisms.’ (Lancet.) (See BLOOD.)

Eosinophilia

Eosinophilia means that an abnormally largenumber of eosinophils are present in the blood-stream This may occur during severe parasiticinfestation in horses and dogs, in certain wastingconditions, and in disease of the lymph system

palate, pharynx and tongue Reddish-brown in

colour, they have raised edges They are not

malignant (compare ‘rodent ulcer’ in man

which is a basal cell carcinoma)

Eosinophilic plaquesmay occur anywhere

on the body but are most common on the

abdomen and inside of the thigh The plaques

are red, with raised edges, and ulcerate They

are extremely itchy

Linear granulomasare seen mainly on the

hind legs and in the mouth, and are

yellowish-pink in colour Itching is not usually present As

with the ulcers mentioned above, females seem

more prone to this granuloma than are males

In the mouth, lesions are ‘more nodular’ and

have to be differentiated from bacterial or

mycotic infections and also carcinoma

Eosinophilic Myositis

(see under MUSCLES,DISEASES OF)

Eperythrozoon Felis

A blood parasite found in cats in Britain, and

first reported in 1959 (See FELINE INFECTIOUS

ANAEMIA.)

Eperythrozoon Parvum

A blood parasite of the pig, which gives rise to

fever, anaemia, and sometimes jaundice It can

be transmitted from pig to pig by lice It occurs

in Britain and the USA Other species of this

parasite affect sheep, and cattle in Africa In the

UK E wenyoni has been isolated from anaemic

cattle (See also HAEMOBARTONELLA.)

Ephedrine

Ephedrine is an alkaloid derived from the

Chinese plant Ma Huang, or prepared

synthet-ically It stimulates the heart and central

nervous system, and relaxes the bronchioles It

has been used for asthma in dogs

Ephemeral Fever (Three-Day

Sickness)

An acute, infectious, and transient fever

accom-panied by muscular pains, and lameness which

has a tendency to shift from limb to limb The

disease was first described in South Africa in

1867 and has been seen in Africa, Asia and

Australia Considerable economic loss has been

caused among beef and dairy cattle in northern

and eastern Australia

Cause A rhabdovirus The disease is sudden

in onset and attacks a large percentage of the

cattle in affected districts, taking the form of an

acute epizootic; then, in a few weeks, it diesdown again as quickly as it arose The disease is

transmitted by insects, including Culicoides

midges The incubation period is 2–10 days

SignsThe disease is ushered in by a suddenlyoccurring rise of temperature which may reach41.6°C (107°F) This is accompanied by loss of appetite, cessation of rumination, rapidrespirations, a quick and full pulse (which,however, may become very weak later), and

a staring coat The affected subject stands with head down The attitude of the patient israther characteristic, the 4 legs being placed far under the body and the back arched, sug-gestive of the position of a horse suffering fromlaminitis There may be a discharge from eyesand nose

In milking cows, the milk yield is muchdiminished Many animals prefer to lie downrather than remain on their feet, and oncedown are most reluctant to get up again Thesymptoms along with the elevated temperaturecontinue like this for about 3 days – hence thename There is usually a considerable loss ofcondition

In Australia the mortality is seldom morethan 0.5 per cent

PreventionVaccines may be available in someareas

‘Epidemic tremors’ is the colloquial name for

a virus disease of poultry characterised by anunsteady gait (See AVIAN ENCEPHALOMYELITIS.)

Epidermis

The outer layer of the SKIN

Epidermis 223

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Epididymis is a structure situated within the

scrotum and in which the sperms mature after

leaving the testicle It has 3 parts: the head

(capus epidiolysis), the body (corpus) and the

tail (cauda).The epididymis has as its outlet the

vas deferens (See TESTIS.)

A venereal disease of cattle and sheep in Kenya

and Southern Africa, and an important cause

there of infertility and sterility

CausePossibly a double infection with a virus

and a mycoplasma; possibly a campylobacter In

sheep, Brucella ovis is responsible (not in the

UK)

SignsThere may be a yellowish discharge from

the vagina, or merely a redness of the mucous

membrane In the bull, enlargement of the

epididymis occurs over a period of months

ControlSlaughter of infected bulls, and use

of AI

Epidural Anaesthesia

Epidural anaesthesia is a form of spinal

thesia induced by the injection of a local

anaes-thetic solution into the epidural space of the

spinal canal The technique is used, for example,

in bovine obstetrics – the injection being made

between the 1st and 2nd coccygeal vertebrae

(See also ANAESTHESIA;ANALGESICS.)

Epigastrium

Epigastrium is the region lying in the middle of

the abdomen, immediately over the stomach

(See ABDOMEN.)

Epiglottis

Epiglottis is a leaf-like piece of elastic cartilage

covered with mucous membrane, which stands

upright between the back of the tongue and

the entrance to the glottis, or larynx It plays an

important part in the act of swallowing,

pre-venting solids and fluids from passing directly

off the back of the tongue into the larynx

Epiglottic entrapment in the horse is

diag-nosed more and more frequently due probably

to the wider use of endoscopy and greater

expertise in its use Affected horses have a

history of decreased exercise tolerance and

they make abnormal inspiratory and expiratorynoises

Epilepsy

Epilepsy is a chronic nervous disorder terised by a sudden and complete loss of consciousness, associated with muscular con-vulsions This is particularly a disease of thedog, although other domesticated animals may

charac-be affected Epileptic fits in the horse were formerly called megrims

Cause The cause of primary or idiopathicepilepsy is a genetic one, whereas secondaryepilepsy may be caused by trauma, neoplasia,infections, cardiovascular disease, or metabolicconditions

The disease can be controlled completely

in about one-third of affected dogs, and erably improved in another third

consid-Secondary epilepsy may be the result of ahead injury, and can occur whenever scar tissue

is formed in the brain

(See also FITS; HYSTERIA; ENCEPHALITIS;

POISONING;HEART DISEASE.)

Signs Attacks usually commence without any warning The limbs are sometimes held out rigidly, and sometimes moved as if the ani-mal were running or galloping The animalchamps its jaws; the eyes are fixed and staring,

or the eyeballs may roll, and the pupils are

dilat-ed There is usually a good deal of salivationfrom the mouth The rectum and the bladderare usually evacuated involuntarily The dogregains consciousness in 1 to 2 minutes; in afew cases consciousness may not be completelylost The 1st fit often occurs between the age of

1 and 3

TreatmentBarbiturates, phenytoin, diazepamand primidone are among drugs used for treat-ment After consciousness returns, the dogshould be placed in a quiet room away fromother dogs or human beings Treatment should

be left to a veterinary surgeon

224 Epididymis

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Epiphora is a symptom of naphthalene

poisoning in cattle

Epiphyseal Fracture

Epiphyseal fracture is one which occurs along

the line of the epiphyseal cartilage, and results

in the epiphysis of a bone becoming separated

from the shaft or diaphysis These fractures may

occur in any young animals before complete

ossification has occurred (See FRACTURES;

BONE,DISEASES OF.)

Epiphysis

The end of a long bone (see BONE,DISEASES OF)

Epiphysitis (Physitis)

Epiphysitis (physitis) may occur in young calves

affected with joint-ill, and has been reported in

adult cattle housed on slatted floors The cattle

were lame, and inflammation and necrosis were

found involving the distal epiphysis of the large

metatarsal bones It also occurs in horses

Episomes

(see PLASMIDS)

Epispastics

Epispastics are substances which produce

blistering on the skin

Epistaxis

Bleeding from the nose (See GUTTURAL POUCH

DISEASE;HAEMORRHAGE.)

Epitheliogenesis Imperfecta

An inherited condition in which there is a gap

in the epithelium which readily bleeds and then

heals by scar tissue It has been seen in foals,

calves, piglets, lambs, and kittens

Epithelioma

Epithelioma is a type of malignant tumour

(See CANCER.)

Epithelium

Epithelium is the layer or layers of cells of

which skin and mucous membranes are

formed The epithelial tissues take many forms

(See SKIN and MUCOUS MEMBRANE.)

Epivag

(see EPIDIDYMITIS;VAGINITIS)

Epizootic

Epizootic is a term applied to a disease which

affects a large number of animals in a large area

of land at the same time and spreads with great

rapidity, e.g foot-and-mouth disease and cattle

plague It is the equivalent term to epidemic inhumans

Epizootic Cerebrospinal Nematodiasis

A disease of horses in Asia, caused by the

migrating larvae of the roundworm Setaria

equina (See ROUNDWORMS.)

Epizootic Haemorrhagic Disease

A virus of deer; it may cause heavy mortality.The signs resemble those of BLUETONGUE insheep

Epizootic Lymphangitis

A chronic contagious NOTIFIABLE DISEASE

disease of the horse family (Equidae) Rare cases have been recorded in cattle, and also inman

Distribution It occurs widely in Asia, inAfrica, and has also been described in America

Cause A fungus, Histoplasma (Cryptococcus)

farciminosa, which gains entry into the body

through a wound, either on the skin or on

a mucous surface The disease is spread by flies,grooming tools, or by any materials which havecome into contact with diseased animals ortheir infective discharges, such as cloths,sponges, and even pails of antiseptic solution

Incubation period Under natural tions at least 1 month, but more commonly

condi-3 or more, may elapse from the time of contamination of a wound till the onset of thesymptoms

Signs Initial signs of the disease are oftenthickenings or ‘cording’ of a lymphatic vessel and the enlargement of the adjacentlymph nodes A fore-limb is usually the site

of the lesions, which include granulomas, nodules which discharge a creamy pus andulcerate Ulcers may form on the mucous membrane of the nose; occasionally on vulva orscrotum

The disease, which runs a slow course lastingweeks or months, has to be differentiated fromglanders A few horses recover

TreatmentIn the UK this is not allowed

Epizootic Pulmonary Adenomatosis

(see under JAAGSIEKTE)

Epizootic Pulmonary Adenomatosis 225

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