W | Veterian Key

W chemical symbol, tungsten (wolfram); tryptophan; watt.

W-plasty a technique in tension-relieving plastic surgery used mostly for the excision of unsightly scars. The edges of the excised part are left in the form of a zigzag and the triangles are interdigitated for suturing.

Waardenburg’s syndrome, Waardenburg–Klein syndrome [vahr’denboorg] a hereditary disorder of humans characterized by pigmentary disturbances, including white forelock, heterochromia iridis, white eyelashes, leukoderma and sometimes cochlear deafness. Blue-eyed, white cats with congenital deafness are considered similar to this syndrome. See also cochleosaccular degeneration.

Wade-Giles one of the techniques used in romanizing the Chinese spoken word. Used extensively in the preparation of veterinary acupuncture literature.

wafers compressed roughage in flat plates useful for feeding to animals in transit.

wahi dermatitis caused by Onchocerca gutturosa.

waivers of responsibility documents signed by clients at the time of admission of their animals to hospital and which set out to absolve the veterinarian from any responsibility for an unfavorable outcome to the case. The documents have little value because they appear to deny the client the natural right to sue for damages.

wakefulness [wāk’fl-nis] believed to occur when the tonic flow of impulses from the reticular activating system exceeds the critical level for sustaining consciousness; reduction of reticular activating system activity is the basis of the pharmacological induction of sedation.

Walchia americana one of the harvest mites that cause trombiculidiasis in domestic animals.

Waldenström’s macroglobulinemia [vahl’den-strrm] see Waldenström’s macroglobulinemia.

Waler an Australian saddle horse of great endurance, ideal for police horses and army remounts (name derives from New South Wales where the horse originated). Bay, brown, black or chestnut; averaging 16 hands high. Called also Australian Waler.

walk [wawk] a slow, four-beat gait of horses in the sequence of near hind, near fore, off hind, off fore.

collected w. the horse is held in but is encouraged to walk vigorously by the rider.

extended w. fast, with long strides and the head carried well out in front. The horse is on a long but not loose rein and must not be hurried nor out of control.

free w. a walk on a loose rein with the head free.

walkabout hepatoencephalopathy in pyrrolizidine alkaloidosis of horses cause by Crotalaria spp. (term originates from Australia). Called also Kimberley horse disease.

Walker hound see Treeing Walker coonhound.

walking [wawk’ing] a normal slow gait in all species.

aimless w. a similar but less severe sign to compulsive walking and part of the dummy syndrome characteristic of hepatic encephalopathy or chronic brain disease.

w. backwards a prodromal sign in pigs before opisthotonos and tetanic convulsions; some horses with colonic impaction will walk backwards, before sitting on their haunches, then lapsing into lateral recumbency.

w. in circles see circling.

w. disease see walkabout.

wall [wawl] a structure bounding or limiting a space or a definitive mass of material.

abdominal w. see abdominal wall.

cell w. a rigid structure that lies just outside of and is joined to the plasma membrane of plant cells and most prokaryotic cells, which protects the cell and maintains its shape.

w. chart see calendar charts, shed sheet.

hollow w. seedy toe.

intestinal w. composed of serosa, muscular tunic, the submucosa containing intestinal submucosal glands, and the mucosa of lining cells, goblet and enterochromaffin cells.

wall-eyed see walleye.

wallaby small macropods, some of them in the same genus (Macropus) as the kangaroos, others in related genera. There are many species including the rock (Petrogale spp.), swamp (Wallabia bicolor), Tammar (Macropus eugenii), Parma (M. parma), hare (Lagorchestes spp.) and nail-tailed (Onychogalea spp.) wallabies.

w. tick see Haemaphysalis bancrofti.

wallaroo a small macropod marsupial in the subgenus Osphranter, similar to the kangaroo and wallaby but with an untidy appearance due to its sombre, brown-black color, shaggy haircoat and straggly facial hairs.

Wallerian degeneration degeneration of a nerve fiber and its myelin sheath that has been severed from its nutritive source.

walleye, wall eye [wawl’i] 1. leukoma; the eye appears white at first glance because of a white opacity of the cornea. Possible causes include inflammation of the cornea and corneal ulcer. 2. strabismus in which there is deviation of the visual axis of one eye away from the other eye, resulting in diplopia; called also exotropia and divergent strabismus. 3. heterochromia iridis; called also ringeyes, watch eye. 4. one of the pike-perch fish; lives in fresh water and is a good source of human food.

wallow mud bath frequented by pigs, elephants, red deer, hippopotami as a cooling aid.

Walpole’s solution an acetic acid and acetate buffer solution at pH 4.5, once used widely to dissolve small struvite crystals and break down gritty plugs in the urethra of cats with feline urological syndrome.

walrus (Odobenus rosmarus) very large, up to 4000 lb, 15–20 ft long, pinniped characterized by the elongated canine teeth (tusks) and whiskers of males. They have a sparse haircoat but derive much protection from the very thick layer of body fat (blubber).

Walton-Liston forceps bone forceps with sharp-pointed blades which do not meet when the jaws are closed; double-actioned, blades straight or angled.

wamps farmers’ name for cattle falling to one side while ataxic. Their explanation is that the cow falls over ‘wamp’. Usually refers specifically to Xanthorrhea spp. poisoning.

wanderers [wahn’dr–r] see neonatal maladjustment syndrome.

wandering [wahn’dr-ing] slow, purposeless walking.

w. Jew see Tradescantia.

Wangensteen clamp ratcheted, scissor type forceps with deep longitudinal grooves on the blade faces. Designed for use in closure of ductus arteriosus.

Wangiella dermatitidis a fungus associated with animal diseases, especially phaeohyphomycosis. Some authorities classify these fungi as Exophiala dermatitidis.

wannakai see Rhodomyrtus macrocarpa.

waoriki Ranunculus rivularis.

wapiti see elk.

war bridle see Yankee war bridle, Magner war bridle.

warbles [wor’blz] the disease caused by Hypoderma. Includes damage to the hides where the larvae emerge, some cases of choke caused by periesophagitis, posterior paresis or paralysis in a small percentage of infested cattle due to a reaction to dead H. bovis in the spinal canal, and some deaths due to invasion of the brain or to anaphylaxis.

Warburg–Dickens scheme [vahr’boorg] see pentose phosphate pathway.

warfarin [wor’fr-in] a coumarin compound used as an anticoagulant in humans and as a rodenticide, with serious toxicity implications for all species. It is readily absorbed from the intestinal tract and acts to inhibit the reduction of oxidized vitamin K, resulting in a depletion of active vitamin K that is required for carboxylation of coagulation factors VII, IX, X and II. Accidental poisoning in all species causes spontaneous hemorrhage and death due to anemia. Less severe cases often show pulmonary hemorrhage. In pigs it is the legs that are affected preferentially and in dogs hemorrhage into the anterior mediastinum and lungs is common. Vitamin K is the specific antidote.

Waring blender syndrome the shearing of erythrocytes by obstructions of the vascular bed, such as heartworms and disseminated intravascular coagulation, resulting in the formation of schistocytes. See also microangiopathic anemia.

warm providing a sensation of approximately body heat.

w. water blanket a device containing circulating warm water; used to apply heat in the prevention or treatment of hypothermia.

w. receptors are not specifically identifiable but a given temperature receptor will respond to warm or cold stimuli but not both.

warm-up pre-race exercise by a horse.

Warmblood thoroughbreds, Arabs and halfbreds (Hanoverian, Holsteiner, etc.) in the German classification of horses. Called also warmblut.

warmblut see Warmblood.

warranty certification that particular animals or chattels are of a particular quality or quantity. Includes warranty of freedom from specifically nominated diseases, warranty of pregnancy, of vaccination or surgical procedure having been performed, of death of an animal. The warranty implies that the vendor will refund the purchase price or replace the item with a comparable one if the first falls short of the warranty.

Warren hound see Portuguese podengo.

wart [wort] see fibropapilloma.

flat w. see auricular plaque.

wart hog (Phacochoerus aethiopicus) a grotesquely ugly member of the family Suidae, or wild pigs. They have large wart-like structures on the face, enormous sickle-shaped tusks, a misshapen head and run with their long tail held rigidly erect.

w. h. disease see African swine fever.

wash [wahsh] a solution used for cleansing or bathing a part, such as an eye or the mouth. See also lavage and specific sites.

washing [wahsh’ing] a technique in the preparation of X-ray films to remove fixative; an important part of producing a good film that will keep for a long time without discoloring.

washing machine sound to- and fro- sloshing sound, synchronous with cardiac contractions, produced when there is fluid and gas (produced by bacteria) in the pericardial sac in cases of traumatic pericarditis.

washout [wahsh’out] to disperse or empty by flooding with water or other solvent.

renal medullary solute w. a syndrome in which the relative hyperosmolarity of the renal medulla is reduced due to an excessive loss of sodium and chloride from the medullary interstitium, usually by diuresis. There is an inability to concentrate urine with polyuria and a compensatory polydipsia.

w. period in drug trials, the period allowed for all of the administered drug to be eliminated from the body.

wasp [wahsp] stinging insect of the order Hymenoptera, suborder Apocrita. There is local irritation at the site of the sting. Animals may be seriously affected if they eat fruit that is infested with wasps at the time. Wasp stings contain histamine, serotonin and ‘wasp kinin’ plus hyaluronidase and phospholipase. Unlike bees, wasps may sting several times.

w. fish venomous fish in the family Tetrarogidae; closely related to the scorpionfish.

wastage a loss of product or productivity; in terms of animal production includes losses due to deaths of animals, lowered production from survivors, including reproduction, and lost opportunity income.

waste [wāst] 1. gradual loss, decay, or diminution of bulk. 2. useless and effete material, unfit for further use within the organism. 3. to pine away or dwindle.

w. disposal techniques for disposing of a veterinary practice’s, or abattoir or feedlot or milking shed wastes. By incineration, deep burial, washed away in a sewer as any other effluent or reclamation for industrial or agricultural use. Disposal of wastes from a veterinary practice or service has additional problems. There is a need for disposal of animal cadavers, kennel and pen wastes, tissue specimens, blood and milk and other samples. Also, there is the risk for the presence of needles and other sharps in the waste. Much of the material is infected, some of it dangerous to humans, and therefore needs to be disposed of legally and systematically.

W-1: Wasting. Ewe showing severe weight loss.

w. management system planned, economic and conservationist program for the recycling and conservation of waste.

recycled w. includes chicken litter, newsprint, sugar cane bagasse, fruit pomace, crude sewage, sewage sludge used as pasture topdressing and feed for farm animals, newsprint used as bedding for horses. See also recycled animal wastes.

wasting [wāst’ing] used in a general sense to indicate serious loss of body weight, or locally to indicate atrophy.

w. acetonemia see primary ketosis.

chronic w. disease (CWD) a fatal transmissible spongiform encephalopathy, prion disease, of free-ranging wild cervids, captive wild cervids, zoological garden cervids and commercial ranch cervids in North America. Characterized by a long incubation period and subsequent changes in behavior, excessive salivation and water consumption, periods of somnolence, loss of body condition and death after a long clinical course. First recognized in the western US in captive cervids (late 1960s) and later in free-ranging cervids (early 1980s), but recently (mid 2000s) has been found in wild cervids in many states east of the Mississippi River. Distribution in North America is largely unknown because adequate surveillance has not been conducted. Also has occurred in ranch elk imported into Western Canada and cervids imported into South Korea. Transmitted laterally, maternally, or through environmental contamination with higher rates of infection in captive cervids probably as a result of high environmental contamination. There is no evidence that CWD prions can be naturally transmitted from infected cervids to humans or to non-cervids, but this is a concern.

postweaning multisystem w. syndrome (PMWS) was first described in 1991 in Western Canada and has since become widespread throughout the world. Produces slow progressive wasting in postweaned pigs with usually a low attack rate but high case fatality. Clinical signs and postmortem findings vary with some pigs jaundiced, some with diarrhea, but most with grossly enlarged inguinal lymph nodes. Respiratory signs are often associated with underlying interstitial pneumonia and pulmonary edema. The cause is uncertain, but caused at least in part by porcine circovirus 2 which is isolated from affected pigs usually in association with porcine reproductive and respiratory syndrome (PRRS). Clinical disease is more common in high health herds, but pigs are often infected without showing clinical disease. Cases of porcine dermatitis and nephropathy syndrome (PDNS) are often seen in herds affected with PMWS. See also porcine dermatitis and neuropathy syndrome.

w. syndrome used to describe terminal stages of feline immunodeficiency virus infection; similar to the cachexia associated with neoplasia.

watch eye lay term for heterochromia iridis; walleye.

water [wah’tr] 1. a clear, colorless, odorless, tasteless liquid, H₂O. 2. an aqueous solution of a medicinal substance.

w. bag see waters.

w. blanket a sheet with water-filled channels through which heated water is circulated by an external pump. This is placed beneath an anesthetized patient to maintain body temperature during surgery and avoid hypothermia.

body w. see total body water.

body w. loss is principally through the urine, supplemented by sweating, fecal water and evaporation in expired air.

w.-damaged grain recorded as toxic due to tunicamycin in mixture produced probably by fungi.

w. deprivation the animals are cut off from any source of water. May be by accident or neglect.

w. deprivation syndrome the animals become frenzied and begin to destroy their surroundings in an attempt to find water. There is abdominal gauntness, sunken eyes and weakness, and abortion may occur later.

w. deprivation test an indirect test of the concentrating ability of renal tubules and their responsiveness to endogenous antidiuretic hormone. Urine specific gravity and/or osmolality is measured before water is withheld, at intervals during, and after an average time period of 12–24 hours. The normal animal should produce urine that is progressively more concentrated, with an osmolality becoming greater than that of the plasma. Used in the diagnosis of diabetes insipidus.

distilled w. water that has been purified by distillation.

w. drowning a primitive method of euthanasia, especially for unwanted, newborn animals.

w.-electrolyte balance the concentration of individual electrolytes and of groups of, e.g. monovalent electrolytes, in serum, in tissue fluids and in intracellular fluid is critical to normal bodily function and is maintained by variation in the renal excretory rate of each electrolyte.

w. homeostasis conservation of body water during times of deprivation or excessive loss due to diarrhea or heavy sweating is affected by an increase in the concentration of the urine by the renal tubules.

w. immersion prolonged head-out water immersion has been used in the treatment of skeletal injuries in horses because of the weightlessness induced but there are serious implications of osteoporosis.

w. intoxication can occur if very thirsty animals, on limited salt intake, are allowed unlimited access to water. There is tremor, incoordination and convulsions and there may be polioencephalomalacia. Hemoglobinuria and hypothermia may also occur.

w. loading test measures the concentrating power of the kidney by combining the water deprivation and ADH tests.

w. marker a substance injected into the body that will diffuse through all of the body water compartments. The reduction in its concentration after injection can be used as a measure of body water. Tritiated water is used for the purpose.

w. marker decay curve the curve of declining concentration of a water marker in intravascular fluid.

w. medication administration of medication in drinking water is used particularly in birds and also in swine.

w. provocative test measurement of intraocular pressure before and after the administration of a large volume of water by stomach tube. A marked increase in intraocular pressure occurs in glaucomatous eyes.

w. seed see hydrocele.

w. vapor partial pressure in humans is the same in venous and arterial blood, in pulmonary alveolar air and in tissues; it is assumed that the same generalization applies to animals.

water betony see Scrophularia aquatica.

water bloom see algae, algal poisoning, cyanobacteria.

water bush Myoporum acuminatum.

water couch Paspalum paspalodes.

water dropwort common name for plants in the genus Oenanthe. Includes fine-leaved water dropwort (O. aquatica), hemlock water dropwort (O. crocata), parsley water dropwort (O. lachenalii).

water figwort see Scrophularia aquatica.

water-jet lavage débridement of necrotic tissue and discharge by the use of a jet of water. A pulsating jet is recommended and the use of excessive pressure (optimum is 60 psi) must be avoided.

water pepper Polygonum hydropiper.

water primrose see Ludwigia.

water rot see fleece rot.

water-soluble vitamin see water-soluble vitamin.

waterbelly anasarca and ascites in cattle, usually that caused by rupture of the bladder or perforation of the urethra in males as a result of obstructive urolithiasis.

waterbuck (Kobus ellipsiprymnus) a medium to large, semiaquatic African antelope; the males have long, spiral horns.

waterfowl a loose term for anseriform birds especially ducks.

watering the giving of water to animals.

w. devices includes, troughs, ball-cock float valves, hydraulic rams, windmills, drinking nipples.

preslaughter w. ad. lib. water facilitates electrical stunning and hide removal and reduces danger of fecal contamination.

waterline disease a disease of black Labrador retrievers; there is pruritus, seborrhea and alopecia of the ventrum and legs. The cause is unknown.

waterpens [Af.] Galenia africana poisoning.

waters [waw’trz] popular name for amniotic fluid. Called also waterbag.

watershed effect [waw’tr-shed] ischemic damage, caused by slow flow of blood because of poor arterial perfusion at the periphery of a circulatory field where there is an inadequate collateral circulation.

Waterside terrier an early name for the Airedale terrier.

watery milk an important observation in the recognition of chronic bovine mastitis; the wateriness can be detected by squirting milk from the suspect quarter into a pool of normal milk from an unaffected quarter, the wateriness is immediately apparent, especially if the test is carried out on a shiny black surface; ingenuity is required if all four quarters are affected.

watery mouth 1. a prominent sign in toxemic newborn calves with colibacillosis. The calf is in a state of toxic shock, is hypothermic, recumbent and wet around the mouth to the point that fluid is dripping from it. 2. a disease of newborn lambs in which this sign is prominent. The cause is obscure but a bacterial cause, possibly Escherichia coli, seems likely.

watery pork the pale, soft exudative pork of pigs affected by porcine stress syndrome.

Watson–Crick helix [waht’sn- krik] James D. Watson (1928- ) and Francis H.C. Crick (1916-2004); along with Maurice Wilkins, codiscoverers of the structure of the DNA molecule and recipients of the 1962 Nobel Prize for Physiology or Medicine. See double helix.

Watsonius watsoni a digenetic trematode found in the intestinal wall of some primates and causes mucohemorrhagic diarrhea, hepatomegaly, ascites and urinary tract disease.

Watson’s test a test which measures urobilinogen and urobilin in urine using ferrous hydroxide to reduce the urobilin to urobilinogen.

watt (W) [waht] a unit of electric power, being the work done at the rate of 1 joule per second. It is equivalent to 1 ampere under pressure of 1 volt.

wattage [waht’j] the output or consumption of an electric device expressed in watts.

wattle¹ one of the fleshy appendages suspended from the head, spectacularly in turkeys, less so in other domestic birds, rarely in goats (tassels; see caprine wattle below), and sheep and pigs.

avian w. a double fold of skin, similar anatomically to the tissue of the bird’s comb, suspended from the mandible of domestic fowls. They are bilateral, without feathers and have a red, meaty appearance.

caprine w’s cylindrical cutaneous appendages that dangle from the throat of some goats. They are fusiform, 1.5–2 inches long, fleshy masses covered with normal skin and suspended usually from the mandibular area but may occur below the ear. Of unknown significance. Thought to be inherited as a single dominant gene. Called also tassel.

w. cholera a localized form of fowl cholera characterized by inflammation and necrosis of the wattles.

w. cyst fluid-filled cystic structure in the wattle of goats, most commonly Nubians; believed to be developmental abnormalities arising from the branchial cleft.

ovine w’s identical to caprine but much less common.

porcine w’s similar to caprine wattles in location and appearance but have a cartilaginous core and thought to be inherited.

W-2: Avian wattles and comb. From Dyce KM, Sack W, Wensing CJG, Textbook of Veterinary Anatomy, 3rd Edition. Saunders, 2002.

wattle² Australian small trees and bushes in the plant genus Acacia in the family Mimosaceae. Includes black wattle (A. cunninghamii, A. salicina), black sally wattle (A. salicina), sally wattle (A. glaucescens), Sydney golden wattle (A. longifolia).

wattmeter [waht’me-tr] an instrument for measuring wattage.

wave [wāv] a uniformly advancing disturbance in which the parts undergo a double oscillation, as a progressing disturbance on the surface of a liquid or the rhythmic variation occurring in the transmission of electromagnetic energy.

brain w’s changes in electric potential of different areas of the brain, as recorded by electroencephalography.

a w. a presystolic positive wave in the jugular vein easily detected in horses and cattle at the jugular inlet and caused by right atrial contraction. Its presence or absence is of value in differentiating partial atrioventricular heart block from sinoatrial heart block.

electromagnetic w’s the entire series of ethereal waves which are similar in character, and which move with the velocity of light, but which vary enormously in wavelength. The unbroken series is known from the hertzian waves used in radio transmission, which may be miles in length (one mile equals 1.6 × 10⁵ cm), through heat and light, the ultraviolet, X-rays, and gamma rays of radium to the cosmic rays, the wavelength of which may be as short as 40 femtometers (4 × 10⁻¹⁴ nm).

w. F, F w. 1. a muscle action potential seen on electromyographs; attributed to antidromically conducted motor nerve action potentials. 2. bidirectional, saw-toothed waves on an electrocardiographic tracing characteristic of atrial flutter. See atrial flutter. 3. in horses, used in reference to atrial fibrillation.

fluid w. see thrill.

light w’s the electromagnetic waves that stimulate the retina. See also vision.

Mayer w’s. waves in arterial blood pressure; brought about by oscillations in baroreceptor and chemoreceptor reflex control systems.

w. motion swirling motion in a drop of dense semen when viewed microscopically (100 × magnification). The intensity and rapidity of the swirling is a reflection of the concentration of the spermatozoa and their level of motility. Called also mass activity.

P w. a deflection in the normal electrocardiogram produced by the wave of excitation passing over the atria.

positive sharp w. an electromyographic tracing associated with denervation and some types of primary muscle disease.

pulse w. the elevation of the pulse felt by the finger or shown graphically in a recording of pulse pressure.

Q w. in the QRS complex, the initial electrocardiographic downward (negative) deflection, related to the initial phase of depolarization.

R w. the initial upward deflection of the QRS complex, following the Q wave in the normal electrocardiogram.

S w. a downward deflection of the QRS complex following the R wave in the normal electrocardiogram.

T w. the second major deflection of the normal electrocardiogram, reflecting the potential variations occurring with repolarization of the ventricles.

T w. abnormalities a common finding in horses whose racing performance worsens. The cause is not identified but may be related to overtraining and the racing of unfit horses. Most animals recover spontaneously with rest. The validity of these abnormalities is now widely doubted.

U w. seen in the human electrocardiogram; represents repolarization of Purkinje cells.

wave mouth the tables of the molar teeth have a wavelike appearance due to uneven wear.

wavelength [wāv’length] the distance between the top of one wave and the identical phase of the succeeding one in the advance of waves of radiant energy.

wax [waks] a plastic solid of plant or animal origin or produced synthetically, used as a vehicle in skin dressings.

bone w. see bone sealant.

ear w. cerumen.

wax flower Hoya australis.

waxing [wak’sing] covering with wax.

poultry w. a technique for removing final hairs and feathers from incompletely plucked birds. They are dipped in hot wax which is removed when it is set.

teat w. a phenomenon in mares which indicates that foaling is imminent. The teats which are already distended suddenly exude a soft waxy covering, probably derived from the thick first colostrum, from the teat orifice. Not a completely reliable guide to an imminent foaling.

waxy casts see urinary casts.

Waygu Japanese cattle renowned for their carcass marbling characteristics, superior eating quality, enhanced flavor, tenderness and juiciness. In demand by other countries for breeding for these characteristics. In Japan, historically hand fed. The dominant black Wagyu strains are Tottori, Tajima, Shimane and Okayama. The dominant red Wagyu strains are Kochi and Kumamoto.

WAZA World Association of Zoos and Aquariums.

Wb weber.

WBC white blood cell (leukocyte); white blood (cell) count.

weak-at-birth due to early parturition, nutritional deficiency, especially of iodine, in the dam, injury during or prolonged birth, intra-uterine infection.

weak calf syndrome a group of undifferentiated diseases of newborn calves characterized by weakness, apathy, reluctance to stand, failure to suck and a humpbacked appearance.

weak lamb syndrome a group of undifferentiated diseases in which the lambs are weak, do not suck well and die of exposure or dehydration and starvation. Among the causes may be poor nutrition of the ewe before lambing, poor lamb-ewe bonding, poor milk supply in the ewe. It is common to find a combination of factors.

weak limb an important concept in the diagnosis of lameness in horses. The affected limb is dragged during progression, and has a low arc in the swing phase of the movement, the limb trembles, knuckles or collapses when weight is put on it, and knuckles or stumbles on it while walking.

weakness a weak bodily state as expressed by reluctance to and difficulty in rising, a shuffling, disinclination to move and then only slowly, eating slowly and a drooping posture. Can be the result of a general toxemia, of a mild form of paralysis, of anemia and other debilitating diseases.

episodic w. one that waxes and wanes, varying from mild or inapparent to severe in the same animal. A characteristic of certain neuromuscular, cardiovascular and metabolic disorders such as myasthenia gravis, polymyositis, hypoglycemia, abnormalities in blood potassium concentrations, and cardiac arrhythmias and conduction blocks.

wean [wēn] to discontinue suckling by the dam and substitute other feeding procedures which may include the provision of milk substitutes or replacers.

weaner a young food animal in the period immediately after weaning and up to 6–8 months of age. Called also weanling.

w. colitis in 6 month old weaner lambs 1–2 months after weaning; characterized by diarrhea and a low case fatality rate. A Campylobacter-like organism can be isolated.

w. illthrift loss of weight at weaning and failure to gain weight subsequently in lambs which appear to have adequate feed and worm control programs. In most cases the problem is multifactorial. Lightweight lambs at weaning are at particular high risk.

weaning the act of separating the young from the dam that it has been sucking, or receiving a milk diet provided by the dam or from artificial sources.

w. age the average age at which groups of lambs, calves or piglets are weaned off milk, which may be provided by the dam or by artificial means. In pastured animals the age is that at which the young animals are judged to be able to survive on their own by grazing, approximately 4–6 months. In intensive farming systems where good quality, well-balanced diets can be fed, and the young kept under close surveillance, early weaning is practiced successfully. Also modern farming methods demand early weaning so that the dams are again available for mating. Dairy calves, sucking pigs and some lambs are now weaned at 2–7 days after birth. Under natural conditions more normal weaning ages, though still subject to a great deal of variation are: calves (4–6 months); lambs, goat kids (8–10 weeks); piglets (30–60 days); foals (5–6 months); puppies (6–8 weeks); kittens (7–8 weeks).

early w. weaning before the young have begun to take significant amounts of alternative diets, e.g. piglets at 3 weeks of age. Usually because of a shortage of feed for the dam, or because of the need to increase the number of young produced per female per year. Segregated early weaning of pigs is a practice to reduce the transmission of disease from sow to offspring. Piglets are removed from the sow at 10–14 days of age and subsequently reared in a separate environment. Medicated early weaning of pigs is similar to segregated early weaning except the sow and litter are medicated with an antimicrobial active against a specific bacteria whose transmission from sow to piglet is being targeted.

heat w. the weaning of commercial chickens away from an artificial heat source at about 4 weeks of age.

w. weight the weight of the young at weaning. Used as a target for young food animals raised for commercial purposes and is an expression of the size at which the young are capable of leading an independent existence. In calves, in particular, the age is related to the development of adequate rumen function. Adjusted weaning weight in beef cattle is the weight immediately at weaning adjusted to 205 days of age and to mature dam age equivalence.

weanling [wēn’ling] see weaner.

w. enteritis see coliform gastroenteritis.

wear and tear pigment lipofuscin. See also xanthosis.

weasel (Mustela spp.) a small, short-legged, serpentine-bodied carnivore of great agility and voracity. Tawny colored, some turning white in winter.

weather climate, climatic conditions.

w. stain said of wool. See fleece rot.

w. stress cold, heat, wet stress.

weatlings see middlings.

weavemouth uneven wear of teeth associated with accelerated attrition. See also wave mouth.

weaver syndrome see progressive degenerative myeloencephalopathy.

weaving a vice of stabled horses manifested by continuous and vigorous rocking from side to side with the head and neck, and to a less extent the trunk.

web [web] 1. network of tissue, reasoning or electronic. 2. a tissue or membrane. See also webbed.

causation w. a network of interacting risk factors.

glottic w. the formation of granulation tissue across the lumen of the larynx, a complication of laryngeal surgery.

split w. a problem of racing Greyhounds. A split develops in the anterior edge of the interdigital web and causes lameness. If it is sufficiently deep it permits excessive spreading of the claws while racing, causing severe injury.

webbed [webd] connected by a membrane or strand of tissue.

weber (Wb) [web’r] the SI unit of magnetic flux which, linking a circuit of one turn, produces in it an electromotive force of one volt as it is reduced to zero at a uniform rate in one second.

Weber–Christian disease see nodular nonsuppurative panniculitis.

Weber–Fechner law in stimulus–response relations the ratio of changes in stimulus strength which are perceptible to a basic strength of the same stimulus is constant.

W-3: Wedge gag. From Bassert JM, McCurnin DM, McCurnin’s Clinical Textbook for Veterinary Technicians, 7th Edition. Saunders, 2010.

weddellite [wed’–līt] a form of calcium oxalate (calcium oxalate dihydrate). Found in oxalate uroliths.

wedder wether.

Wedelia genus of plants in America and Australia in the family Asteraceae; contain a carboxyatractyloside, wedeloside; causes acute hepatic necrosis, nephrosis and sometimes cardiomyopathy, congestive heart failure, death; includes W. asperrima (yellow daisy, sunflower daisy), W. glauca (Pascalia glauca, sunchillo). See also Wollastonia biflora.

wedeloside carboxyatractyloside found in Wedelia asperrima.

wedge [wej] a solid rectangular object, thin at one end, thick at the other.

mouth w. made of metal; used to force open the molar arcades of the anesthetized horse or cow. The planes on which the molars ride are roughened to prevent slippage. Called also Bayer gag.

w. test a diagnostic test used to localize the cause of lameness in horses. The horse stands on a wooden wedge placed under a specific part of the hoof, placing pressure on certain structures or to cause extension of joints or tendons.

WEE Western equine encephalomyelitis.

weed 1. a plant growing out of place. 2. of horses, see sporadic lymphangitis.

noxious w. a plant defined by law as being particularly undesirable, invasive and difficult to control.

Weed method problem knowledge coupler system.

weedfish where a fish, e.g. carp, escapes from a fish farming habitat and populates a natural environment where it destroys natural breeding habitats of native fish.

weedkiller see herbicide.

Weeksella a genus of gram-negative, glucose-non-fermenting bacteria which are normal flora of dogs and cats.

weeping said of frozen meat on thawing; the fluid that runs away as thawing proceeds. It contains myoglobin, salts and protein and is fluid leaked from muscle fibers ruptured by the formation of crystals during the freezing stage. The amount of weeping, and it can represent 2.5% of the weight of a carcass, is greater if the freezing was done slowly and if the carcass is of poor quality. Beef is affected more than the other meats. Called also carcass drip.

weepy eye 1. a lay term for ocular discharge. 2. specifically, a conjunctivitis of rabbits caused mostly by Pasteurella spp. and characterized by ocular discharge which is soon spread over the face by the rabbit rubbing the eyes with its paws.

Wehrdikmansia see Onchocerca.

Wei qi in traditional Chinese medicine, the equivalent of the immune system. See also Qi.

Weibel-Palade body [vi’bl pah-lād’] ultrastructural markers of endothelial cells in primates and horses.

weight [wāt] heaviness; the degree to which a body is drawn toward the earth by gravity. See also Tables 2.1 and 2.2.

apothecaries’ w. an outmoded system of weight used in compounding prescriptions based on the grain (equivalent 64.8 mg). Its units are the scruple (20 grains), dram (3 scruples), ounce (8 drams) and pound (12 ounces). See also Tables 2.2 and 2.3.

atomic w. the weight of an atom of a chemical element, compared with the weight of an atom of carbon-12, which is taken as 12.00000.

avoirdupois w. the system of weight still used for ordinary commodities in some English-speaking countries. Its units are the dram (27.344 grains), ounce (16 drams) and pound (16 ounces).

birth w. weight of the newborn at the time of birth.

body w. the animal’s weight. In herbivores this is often debatable because of the variation in ‘gut-fill’ depending on the availability of palatable food. In the absence of scales the weights of large animals are often estimated on the basis of their age and their girth just behind the elbow. Called also liveweight. See also body condition score.

body w.-to-surface area determination of many drug dosages is physiologically more accurate when based on body surface area rather than body weight; used particularly in cancer chemotherapy. For conversion table for use in dogs see Table 20.

equivalent w. the weight in grams of a substance that is equivalent in a chemical reaction to 1.008 g of hydrogen. See also chemical equivalent.

w. gain increase in body weight for specific periods; the principal measure of productivity in meat animals.

w. loss the loss of body weight from that previously measured. This estimate must take into account the difference in ‘gut-fill’ and the effects of developing pregnancy and recent parturition.

metric w. see Tables 2.1 and 2.2.

molecular w. (mol. wt.) the weight of a molecule of a chemical compound as compared with the weight of an atom of carbon- 12; it is equal to the sum of the weights of its constituent atoms. See also Table 4.

over w. see overweight.

shifting w. limb to limb sign indicative of lameness especially in horses; while standing the horse is continually shifting its weight from one limb to the opposite one of the pair.

weightlessness in horses induces osteoporosis if the period of weightlessness is long enough; in dogs the effects of weightlessness are confused with those of head-out immersion in water.

weight/volume measurement the system in which the solids are weighed and the fluids measured volumetrically.

Weil’s disease human leptospirosis caused by Leptospira icterohaemorragiae and transmissible from rats to humans.

Weimaraner a medium- to large-sized dog with a distinctive short, silver-gray coat and amber, gray or blue-gray eyes, used for pointing and retrieving game. The ears are long and pendulous, the neck is long, and the tail is docked to a medium length. Outside the USA, a longhaired variety is recognized. The breed is predisposed to spinal dysraphism, hemophilia A and an immunodeficiency syndrome. Called also gray ghost.

Weinberg pen a pen for restraining adult ruminants which are to be slaughtered by the Jewish or Muslim methods.

weir vine Ipomoea polpha subsp. weirana.

Weitlaner retractor a self-retaining instrument, shaped like a scissors but the blades open when the ratcheted handles are closed. The blades each have four downward-pointing, curved prongs which retain their position in a spread wound.

Welch bacillus [welch] see Clostridium perfringens.

welding fumes inhalation causes acute chemical irritation and bronchitis; severe cases develop pulmonary emphysema.

well ribbed-up a good spring of ribs with a short, well-muscled flank or coupling to the hindquarter.

well waters can be poisonous; see nitrate, sodium chloride poisoning.

Wellingtons see gum-boots.

Welsh black dual-purpose black cattle breed originating in Wales, UK.

Welsh corgi a medium-sized, long, muscular dog with very short legs. Two types are recognized as separate breeds: Cardigan Welsh corgi, which is larger, has large, rounded, erect ears, a short, hardtextured coat, and a long, bushy tail. Pembroke Welsh corgi, which is more common, has a shorter body, smaller, pointed, erect ears, a medium length coat, and a very short, natural or docked, tail. The breeds are predisposed to cystinuria, intervertebral disk disease and progressive retinal atrophy.

Welsh mountain sheep a white or tan-faced wool and meat sheep; males are horned, females polled.

Welsh pig a long-faced, lop-eared, white pig, originating in Wales, UK.

Welsh pony 1. Welsh Mountain pony, a riding pony of any color but not broken colors, up to 12 hands high. 2. Welsh pony, similar to the Welsh Mountain pony but larger, up to 13.2 hands high. 3. Welsh cob.

Welsh springer spaniel a medium-sized dog of the spaniel type, midway in size between the Cocker spaniel and English springer spaniel. It is compact with pendulous ears, docked tail, and a red and white, thick, silky coat that is flat on the body but forms feathering on the legs, ears and under the body. Called also Starter.

W-4: Welsh mountain wool sheep. From Sambraus HH, Livestock Breeds. Mosby, 1992.

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