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

Xylazine A sedative used to render animals easier to han-dle, it is widely used in dogs, cats, horses, farm livestock, and zoo animals.. Cases of poisoning have been noted among horses,

X-Raysare high-energy radiation capable of

passing through considerable thicknesses of

many substances which are opaque to ordinary

light, without undergoing material absorption,

but other substances, even in very small

thick-nesses, are able to absorb the great majority of

the rays: thus, flesh is very transparent; healthy

bone is fairly opaque Widely used for

diagnos-tic imaging of internal body structures and

(in human medicine) for radiotherapy

PrecautionsGuard screens of lead glass,

rub-ber impregnated with lead, or sheet lead, are

used to protect the operators of radiographic

apparatus, and precautions are necessary to

shield the testes and ovaries of young persons

and animals from the sterilising effects of the

rays

Detailed precautions are as follows:

1 Persons under 16 years must not take part

in radiological procedures

2 Fluoroscopy (imaging) or radiotherapy

should not be carried out except under expert

radiological guidance Hand-held fluoroscopes

must not be used in any circumstances

3 Personnel radiation monitoring devices,

such as film badges, must be worn by all

per-sons who take part routinely in radiological

procedures

4 The animal should, if possible, be

anaes-thetised or tranquillised for radiography, and all

persons should withdraw as far as practicable

from the useful beam

5 If it should be necessary to hold the

ani-mal for radiography, lead-protective gloves and

aprons must be worn Whenever possible,

hold-ing should be done by the owners, unless they

are under 16 years or pregnant

6 Persons should not expose any part of

their bodies to the useful beam even when

wearing protective clothing

7 The useful beam should be restricted to

the area being examined by means of a

beam-limiting device

Notes on protection against radiation will

also be found in the British Veterinary

Association’s guide to the Health and Safety at

Work Act

Regulations In the UK, the Ionising

Regulations 1985 require veterinary surgeons

using X-ray equipment to notify their local Health and Safety Executive Many veterinary practices now employ a radiation protection adviser to ensure compliance with the require-ments of the regulations

Radiography The production of a radi-ograph of the internal structure of a small ani-mal is a comparatively simple matter once the difficulty of control is overcome The animal is arranged upon the table in such a position as to allow the rays to pass down through the part and become registered upon a sensitive plate placed flat upon the table immediately below The animal may lie upon its back, on one or the other side, or on its chest and abdomen with the legs pulled out from under it To maintain this position it is always advisable to administer

an anaesthetic The discharge tube is best arranged immediately above the animal in such

a position as to allow the rays to fall perpendic-ularly down through the body on to the plate (For screening, the tube must be below the table, and the screen held or supported above the animal.) The period of exposure to the pas-sage of the rays varies according to the tissues,

to the type and power of the equipment, to the distance of the tube from the plate, and to whether or not an intensifying screen is used There are many conditions in which the actual extent of injury or disease can be accu-rately discovered by the use of X-rays, but the most important are diseases and injuries of bones Fractures of the limb-bones are well shown, and their extent is better realised than is possible by palpation Exostoses (overgrowths

of bone) can also be clearly indicated, while tumour formation (usually sarcomatous) shows

as a thinning and enlargement of the bone tissue Where only one limb is affected it is advisable to arrange the animal so as to include

a picture of the normal limb for comparison Foreign bodies – especially needles, pins, nails, and other metallic substances – which have been swallowed are best shown by a profile view

of the abdomen Pieces of game bones (which are specially dense and show up well) can also

be seen in the stomach or intestines, and are very often surrounded by gas, which, in the negative, appears as a dark shadow – the bone itself appearing light Internal tumours can very often be diagnosed They appear as more or less discrete pale areas in positions where a radi-ograph from a normal animal is denser under the same conditions of exposure, etc Certain tumours can be made to show up well by giving the animal medicinal doses of a lead salt for a few days before taking the plate Some of the

X

lead becomes deposited in the tumour and

intensifies the contrast Where some

displace-ment, stricture, or dilatation of the stomach or

of part of the intestinal canal is suspected, the

animal is given a feed or a draught containing

an emulsion of bismuth or barium carbonate,

or some other harmless metallic salt, or has some of the same material injected into the rec-tum After waiting until the salt has become suitably distributed, a radiograph of the

Xanthosis 785

X

A teaspoon in the stomach of a cocker spaniel The spoon was swallowed while the animal was being given cod-liver oil (Reproduced by courtesy of Mr S W Douglas, University of Cambridge School of Veterinary Medicine.)

Radiography reveals that a painful swelling on the leg of a St Bernard is due to an osteosarcoma involving the radius (Reproduced by courtesy of Mr S W Douglas, University of Cambridge School of Veterinary Medicine.)

786 Xanthosis

abdomen is taken, and the outlines of those

organs to which the salt has been carried by

peristalsis, can be made out as pale areas in the

negatives

Other conditions in which X-rays are useful

are as follows: stones in the kidney, urinary or

gall-bladder; dilatation of the heart;

solidifica-tion of a porsolidifica-tion of a lung; and pleurisy

Portable X-ray apparatus is available for use

in, for example, examining the lower limbs of a

horse at the stable

Computed tomography A sophisticated

and effective method of visualising the interior

of the body, this has revolutionised radiography

A focused electronic imaging scanner is used to

build up, by a series of consecutive exposures, a

picture of an organ or specific area The

result-ing image is enhanced by computer analysis

and viewed on a visual display unit (VDU)

which shows a clear picture without the the

superimposition of other body tissues which

surround the targeted area In the apparatus,

whose British development was by Godfrey

Hounsfield FRS, crystal detectors are used in

place of the film in a normal X-ray system

Radiotherapy X-ray therapy has been

applied to a limited extent in the treatment of

certain tumours in the dog

Xanthosis

Xanthosis is a yellowish-brown pigmentation of meat, generally affecting the heart and the tongue It gives the meat an objectionable colour, but is quite harmless

Xenophthalmia

Inflammation of the eye caused by a foreign body

Xerophthalmia

A disease of the eye associated with a vitamin A deficiency There is thickening and cloudiness

of the conjunctiva and cornea; blindness may result

Xylazine

A sedative used to render animals easier to han-dle, it is widely used in dogs, cats, horses, farm livestock, and zoo animals It is also used for pre-anaesthetic medication and for general anaesthesia in combination with ketamine Xylazine increases blood glucose levels and urine output Side-effects may include brady-cardia, slower breathing, and lowered blood pressure In cattle tolazoline has been used as a xylazine antagonist

Yarded Cattle

Before yarding cattle in the autumn, it is wise to

make a gradual change from sugar-poor

autumn pasture to things like roots; otherwise

digestive upsets are likely to occur

Similarly, in spring it is a mistake to turn

calves straight out on to grass This means a

sudden change from protein-poor food to

the rich protein of the early bite, and the

resulting effect upon the rumen will set them

back It is best to get them out before there

is much grass for a few hours each day;

let them have hay and shelter at night to protect

them from sudden changes of weather

Hypomagnesaemia, too, is far less likely under

these circumstances (See also HOUSING OF

ANIMALS.)

Boss cows can be a nuisance in yards, but the

provision of yokes for feeding overcomes the

main diffculty

When self-feeding of silage is practised,

pre-cautions are necessary in order to prevent foot

troubles (See SILAGE.)

Yarded animals fed on cereals, sugarbeet

pulp, straw, and hay – but with little or no

greenstuff – may suffer from xerophthalmia and

go blind as a result of a vitamin A deficiency

Yawning

Yawning is an important sign of KIMBERLEY

HORSE DISEASE; it may also be seen in cases of

LABURNUM POISONINGand NARCOLEPSY

Yeast

Yeast is a valuable source of vitamin B, but

should not be fed in excessive amounts to pigs

or it may give rise to rickets unless adequate

vit-amin D is simultaneously available Yeast has

proved successful in the treatment of tropical

ulcers in humans, and success has been

report-ed in a limitreport-ed number of cases in horses in the

tropics The human patients were mostly those

whose diet was deficient in vitamin B, a

defi-ciency further increased by sweating The yeast

was applied directly to the ulcer, and a small

quantity given internally also

Yeasts

Yeasts sometimes cause enteritis, and are

impor-tant in some cases of refractory otitis in the dog

(See FUNGAL DISEASES.)

Yellow Fat Disease of Cats

(see STEATITIS)

Yellow Fever

A viral disease affecting man and other verte-brates, principally monkeys, in large areas of tropical America and Africa There are 2 known cycles of transmission, the urban and jungle cycles In the urban cycle, man is the reservoir

and Aedes aegypti probably the only vector This cycle from man to A aegypti to man is now

virtually unknown in the Americas owing

to efforts to eradicate the vector, but it is still common in Africa

The jungle cycle has a primate reservoir maintained by various mosquitoes Movement

of virus from the monkey-mosquito-monkey cycle into man is accidental, and is the result

of human penetration into jungle where the disease is endemic

The causative organism is classified as a flavivirus

Yelt

A female pig intended for breeding, up to the time that she has her 1st litter

Yersiniosis

Infection with Yersinia pseudotuberculosis or with Y enterocolitica.

Up to 1960, states WHO, only the former organism was regularly isolated in man and animals in Europe; but since then most of the

isolations have been of Y enterocolitica.

‘Pseudotuberculosls’ in the early 1990s was still occasionally found in rodents and birds, especially in France and the UK, and is a zoonosis People may become infected through pets such as guinea pigs, hamsters, and cats, all

of which may have a subclinical infection only

but excrete Y pseudotuberculosis.

An investigation in Invermay, New Zealand,

resulted in Y pseudotuberculosis being isolated

from 675 apparently healthy small mammals and birds In descending order of prevalence were feral cats (27.8 per cent), Norway rats (8.6 per cent), mice, hares, rabbits, ducks, sparrows, seagulls and starlings

In New Zealand, yersiniosis has also emerged

as a serious disease of farmed red deer It appears to be triggered off by stress, and most cases occur during the winter

Cats(which are liable to become infected by their prey) may also show clinical symptoms: loss of appetite, vomiting and diarrhoea Also loss of weight

Y

PheasantsYersiniosis is an important cause

of death of these birds in the UK

Yersinia enterocolitica infection in Europe

was first found in hares, in outbreaks of disease

on chinchilla farms, in monkeys in zoos, and in

guinea pigs There may be enteritis and other

lesions, but symptomless carriers have been

found among all the farmyard mammals and

birds

Occasionally Y enterocolitica has been

isolat-ed from cases of mastitis in cows, endocarditis

in bulls, and septicaemia in pigs In cattle, the

antibody produced may be difficult to

differen-tiate from that produced by Brucella abortus.

Camels, foxes, and fleas may also carry the

organism

Public healthYersinia enterocolitica infection

is not regarded as a genuine zoonosis by WHO

Person-to-person infection occurs, and also

infection from soil-contaminated vegetables

The human illness is characterised by enteritis,

and is a cause of diarrhoea, although less

impor-tant than salmonella and campylobacter Ileitis

may be accompanied by acute pain, suggestive of

appendicitis A mesenteric adenitis is also seen,

and sometimes polyarthritis, deep abscesses, eye

lesions, and occasionally septicaemia

In the UK in 1984, 250 cases were reported

Outbreaks in North America have been linked

to raw milk (For Y pestis seeBUBONIC PLAGUE,

which can occur in cats and dogs in subclinical

form.)

Yew Poisoning

All varieties of the British yew trees are

poiso-nous, but owing to its more frequent

cultiva-tion, the common yew (Taxus baccata) is most

often responsible for outbreaks of poisoning

among animals The Irish yew (T baccata var.

fastigiata) and the yellow yew appear to contain

less of the poisonous alkaloid, which is called taxine The bark, leaves and seeds all contain it The older dark leaves are more dangerous than the fresh green young shoots, which cattle have been known to eat in small amounts without harm Cases of poisoning have been noted among horses, donkeys, mules, cattle, sheep, goats, pigs, deer, rabbits, and even pheasants, but the majority of cases occur in young store cattle and in dairy cows which have access to the shrubberies, graveyards, etc., where yew trees are most common

SignsIn many cases cattle drop dead without showing any preliminary symptoms at all They may fall while cudding almost as suddenly as if shot In other cases where less has been eaten, excitement and paresis may be seen

Treatment Antidotes are as for alkaloids If time allows, rumenotomy may be carried out

Yolk Sac Infection

(see OMPHALITIS OF BIRDS)

Yorkshire Terrier

A long-haired, black-and-tan coloured toy dog The breed is prone to tracheal collapse caused

by a cartilage defect that may or may not be inherited Patellar luxation is inherited as a recessive trait

Yorkshire Boarding

Vertically arranged boards with a gap between each, used for partial cladding of a livestock building It is a very useful means of improving ventilation and avoiding condensation, thereby reducing the risk or incidence of bronchitis and pneumonia in housed livestock

788 Yew Poisoning

Y

An oestrogenic toxin from the fungus Fusarium

graminearum of standing corn The toxin has

caused abortion in sows, and possibly a splayleg

condition in piglets

Zebu

Bos indicus, the cattle of India, East and West

Africa, and Southeast Asia The American name

is Brahman; in South Africa, the Afrikaner

Zero-Grazing

Taking cut fodder to yarded cattle, or to cattle

in exercise paddocks Zero-grazing has a place

on heavy land, with high stocking rates and

large herds It obviates poaching and the

spoil-ing of grass, and a given acreage zero-grazed can

provide more grass than if grazed It means,

however, cutting grass every day, and

mechani-cal failures can upset the system It is not yet

considered economic for sheep

Zinc (Zn)

Zinc (Zn) is a trace element, and a deficiency

has occurred in pigs (See PARAKERATOSIS.) A

zinc supplement to prevent or correct this

con-dition must be used with care, as 1000 parts per

million can cause poisoning It seems that a

high calcium intake by pigs aggravates a zinc

deficiency

A zinc deficiency may also occur in dogs,

especially in those fed largely on flaked maize or

‘loose cereal-based diets’ Signs include a

predis-position to skin infections, a poor coat,

localised alopecia, and hardening of the skin in

places Response to a zinc supplement is

usual-ly quick (See SHEEPDOGS.)

A zinc supplement has been used to protect

sheep against facial eczema due to ingestion of

the mycotoxin sporidesmin

External uses Zinc oxide is an ingredient

of ointments; the carbonate an ingredient of

calamine lotion used for moist eczema, etc The

sulphate in weak solution has been used in

wound treatment and in eye lotions; the

chloride – a caustic – to repress granulations

Zinc Bacitracin

An antbiotic formerly used as a feed additive to

improve growth rate in most farm animals and

egg production in poultry (See ADDITIVES.)

Zinc Poisoning

Chronic zinc poisoning has been reported in a dairy herd as a result of contaminated drinking water – caused by interaction between copper pipes and newly galvanised tanks The main symptom was chronic constipation throughout the herd, and a diminished yield from the cows

in milk

Fatal zinc poisoning has occurred in dairy cattle fed on dairy nuts to which zinc oxide has been added instead of magnesium oxide The first death occurred after 3 weeks

Zinc-responsive skin diseaseThe most common cause of this is the feeding of soya or cereal-based diets – with little or no meat, which is rich in zinc Some dogs may have an inherent defect which limits zinc absorption

Signs A dull, harsh coat; sometimes with whitish crusts on the skin

Zondek-Ascheim Test

(see PREGNANCY DIAGNOSIS)

Zoo Licensing Act 1981

The Zoo Licensing Act 1981 is intended to pro-mote animal welfare and public safety at zoos It covers any collection of wild animals (including mammals, birds, reptiles, fish, and insects) in Britain to which the public has access for more than 7 days in any 12-month period; but exempts pet shops and circuses, as these are cov-ered by the Pet Animals Act 1951 and the Performing Animals (Registration) Act 1952

Of 150 zoos inspected following the passing

of the Act, only 5 were refused a licence; and in those cases it was public-safety considerations rather than the quality of animal care which brought about the refusal

Zoonoses

Diseases communicable between animals and man Information about them will be found under the following headings: ARIZONA INFEC-TION; BABESIA –Babesiosis; ANTHRAX;B VIRUS

(from monkeys); BRUCELLOSIS; CAT-SCRATCH FEVER;CHAGAS DISEASE;EQUINE ENCEPHALITIS;

EQUINE INFECTIOUS ANAEMIA; FOOT-AND-MOUTH DISEASE(very rare in human beings);

GLANDERS; HYDATID DISEASE; LEPTOSPIROSIS;

LISTERIOSIS;LIVER-FLUKES;LOUPING-ILL;LYME DISEASE; LYMPHOCYTIC CHORIOMENINGITIS

(from mice); NEWCASTLE DISEASE;ORNITHOSIS;

ORF;PASTEURELLOSIS;Q FEVER;RABIES;RATBITE FEVER;RIFT VALLEY FEVER;RINGWORM;ROCKY MOUNTAIN FEVER; RUSSIAN SPRING-SUMMER VIRUS;SALMONELLOSIS;SCABIES;

SCHISTOSOMI-Z

ASIS;TAPEWORMS;TICK-BITE FEVER;TICK

PARAL-YSIS;TOXOCARA;TOXOPLASMOSIS;TRICHINOSIS;

TUBERCULOSIS;TULARAEMIA;VESICULAR

STOM-ATITIS; MARBURG DISEASE; WESSELBRON

DIS-EASE;YERSINIOSIS;YELLOW FEVER;SWINE

VESIC-ULAR DISEASE; PORCINE STREPTOCOCCAL

MENINGITIS;ROTAVIRUS;LASSA FEVER;BOVINE

ENCEPHALOMYELITIS;LEISHMANIASIS;BUBONIC

PLAGUE;ENCEPHALOMYOCARDITIS.)

It should be added that typhus and plague

may be transmitted, by flea-bite, from rats; and,

in jungle areas, yellow fever, by

mosquito-bite, from monkeys (See also under RODENTS;

MONKEYS;INFLUENZA.)

Among skin diseases, the parasite of

follicu-lar mange may occasionally infest the human

eyelid Among eye infections, INFECTIOUS

BOVINE KERATOCONJUNCTIVITIS should be

mentioned Human enteritis has followed

con-tact with sheep affected with campylobacter

abortion

(See also BIRD-FANCIER’S LUNG;MELIOIDOSIS;

CAMPYLOBACTER INFECTIONS; CHLAMYDIA;

PSITTACOSIS; BOUTONNEUSE FEVER;

LEISHMA-NIA; HANTAVIRUS;TICK-BORNE ENCEPHALITIS;

EHRLICHIA CANIS;ABORTION,ENZOOTIC.)

Zoonoses in UK Veterinarians

A questionnaire was distributed to 1717

mem-bers of veterinary and support staff of the

Ministry of Agriculture and the Institute for

Research on Animal Diseases; 1625 (95 per

cent) responded, comprising 563 veterinary

surgeons, 690 scientific staff and 372 technical

support staff A total of 1057 (61.5 per cent)

had apparently not suffered any zoonotic

infec-tion Animal ringworm was the commonest

reported zoonosis The incidences of ringworm,

brucellosis and Newcastle disease were higher

in the veterinary and support staff than in the

laboratory workers In contrast, ornithosis, salmonellosis and Q fever occurred at least as often in the laboratory staff Fourteen people developed tuberculosis during their employ-ment, although only 1 was caused by

Mycobacterium bovis The veterinarians

report-ed 441 injuries that resultreport-ed from accidents at work; 397 (71 per cent) of these involved ani-mal-handling The comparable figures for labo-ratory workers and technical staff were 329 and

103 (15 per cent) and 198 and 179 (42 per cent) respectively

Zoonoses Orders 1988 & 1989

These include measures intended to reduce the risk to humans of salmonella and brucella infections of animal origin The 1989 Order recognises bovine spongiform encephalopathy

as a zoonotic disease

Zootechny

Animal management

Zygoma

Zygoma is the bridge of bone which runs from near the base of the ear to the lower posterior part of the eye-socket It protects the side of the bony orbit, forms part of the support of the outside of the joint of the lower jaw with the rest of the head, and serves as a base of attach-ment for part of the strong masseter muscle which closes the mouth and is important in the chewing of the food The zygomatic arch (another name for the zygoma) is formed by projections from the temporal, zygomatic, and maxillary bones

Zygote

The body that results from the fertilisation of

an egg cell by a sperm

790 Zoonoses in UK Veterinarians

Z

Animal Health Trust PO Box 5,

Newmarket, Suffolk CB8 8JH 01638 750659

Association of Pet Behaviour

Counsellors PO Box 46, Worcester WR8

9YS 01386 751151

Association of Pet Dog Trainers

Peacock’s Farm, Northchapel, Petworth, West

Sussex GU28 9JB

Blue Cross 1 Hugh Street, London SW1V

1QQ 020 7834 1128

British Cattle Movement Service

Curwen Road, Workington, Cumbria CA14

2DD 0845 0501234

British Cattle Veterinary Association

The Green, Frampton-on-Severn,

Gloucestershire GL2 7ER 01452 740816

British Equine Veterinary Association

5 Finlay Street, London SW6 6HE 020 7610

6080

British Horse Society British Equestrian

Centre, Stoneleigh Deer Park, Kenilworth,

Warwickshire CV8 2LR 08701 220224

British Rabbit Council Purefoy House, 7

Kirkgate, Newark, Nottingham NG24 1AD

01636 676042

British Veterinary Association 7

Mansfield Street, London W1G 9NQ 020

7636 3541

Companion Animal Welfare Council

43 Brook Field Lane, Harlow, Essex CM18

7AU

DARD (Department of Agriculture

and Rural Development) Dundonald

House, Upper Newtownards Road, Belfast BT4

3SB 028 9052 4580

DEFRA (Department of the

Environment, Food and Rural Affairs)

1A Page Street, London SW1P 4PQ

Donkey Sanctuary Sidmouth, Devon

EX10 0NU 01395 578222

Farm Animal Welfare CouncilDEFRA,

1A Page Street, London SW1P 4PQ

Farriers Registration Council Sefton House, Adam Court, Newark Road, Peterborough PE1 5PP 01733 319911

Kennel Club1 Clarges Street, London W1Y 8AB 0870 6066750

National Association of Farriers, Blacksmiths & Agricultural Engineers

The Forge, Avenue B, 10th Street, NAC, Stoneleigh, Warwickshire CV8 2LQ 024 7669 6595

National Canine Defence League 17 Wakely Street, London EC1V 7LT 020 7837 0006

National Farmers Union Agriculture House, 164 Shaftsbury Avenue, London WC2

National Office of Animal Health 3 Crossfield Chambers, Gladbeck Way, Enfield, Middlesex EN2 7HF

National Poisons Information Service

Avonley Road, London SE14 5ER 020 7635 9195

NOAH (National Association of Animal Health) 3 Crossfield Chambers, Gladbeck Way, Enfield, Middlesex EN2 7FH

020 8367 3131

PDSA (People’s Dispensary for Sick Animals) Whitechapel Way, Priorslee, Telford, Shropshire TF2 9PQ 01952 204713

Pets Travel Scheme (PETS) Helpline:

0870 41171; fax 020 7904 6834; e-mail pets@ahvg.maff.gov.uk/animalh/quarantine

Royal College of Veterinary Surgeons Belgravia House, 62–64 Horseferry Road, London SW1P 2AF 020

7222 2001

RSPCA (Royal Society for the Prevention of Cruelty to Animals)

Causeway, Horsham, West Sussex RH12 1HG

01403 264181

UFAW (Universities Federation for Animal Welfare) The Old School, Brewhouse Hill, Wheathampstead, Hertfordshire AL4 8AN 01582 9303611

USEFUL ADDRESSES