V

V

V chemical symbol, vanadium; symbol, volt; vision; visual acuity.

V_d volume of distribution.

V_T tidal volume.

v. [L.] vena (vein); pl. venae (vv.) [L.].

V–D–J joining see antibody.

V domain the variable region or domain of immunoglobulins.

V factor see diphosphopyridine nucleotide.

V–J joining see antibody.

V region variable region of immunoglobulins.

v tach ventricular tachycardia.

V to Y plasty a tension-relieving technique for closure of a skin incision in which a V-shaped incision is made alongside the primary incision and then closed in a Y shape.

vaalstorm Thesium lineatum.

VAC vincristine, doxorubicin and cyclophosphamide; a cancer chemotherapy regime.

vaccigenous producing a vaccine.

vaccina [vak-si’n] vaccinia virus.

vaccinable susceptible of being successfully vaccinated.

vaccinal [vak’s-nl] 1. pertaining to vaccinia, to vaccine, or to vaccination. 2. having protective qualities when used by way of inoculation.

vaccinate [vak’s-nāt] to inoculatewith vaccine to produce immunity.

vaccination [vak“s-na’shn] the introduction of vaccine into the body to produce immunity to a specific disease. The vaccine may be administered by subcutaneous or intradermal injection, by infusion into the mammary gland, by mouth, by inhalation of an aerosol or administration in food or drinking water. The term vaccination comes from the Latin vacca, cow, and was coined when the first inoculations were given with organisms that caused the mild disease cowpox to produce immunity against smallpox. Today the word has the same meaning as immunization.

v. failure following administration of a vaccine, the animal develops the disease. The cause is often related to faulty inactivation of the vaccine due to improper handling or inappropriate administration, or the animal was incubating the disease at the time of vaccination.

v. schedules specified ages and intervals for administration of vaccines to ensure the best immunological response.

simultaneous serum-virus v. simultaneous administration of live virus and hyperimmune serum. Used at one time in the control of several diseases, including canine distemper and classical swine fever (hog cholera).

vaccine [vak-sēn’] a suspension of attenuated or killed microorganisms (viruses, bacteria, fungi or nematodes), or products of them, administered for prevention, amelioration or treatment of infectious diseases.

anti-idiotype v. antibody made to antigenic determinants located in the variable domains of immunoglobulin molecules.

v.-associated sarcoma see sarcoma.

attenuated v. a vaccine prepared from live microorganisms that have lost their virulence but retained their ability to induce protective immunity. Attenuated microorganisms including particularly bacteria and viruses may be found naturally or they may be produced in the laboratory, for example by adaptation to a new medium or cell culture or they may be produced by recombinant DNA technology.

autogenous v. a vaccine prepared from cultures of material derived from a lesion of the animal to be vaccinated, e.g. wart vaccine.

bacterial v. a preparation of attenuated or killed bacteria, used to immunize against organisms, or sometimes for pyrogenetic effects in treatment of certain noninfectious diseases.

biosynthetic v. a formulation containing a protective, noninfectious, immunogenic subunit produced in or by a biological system.

caprinized v. a vaccine, usually a virus, attenuated by serial passage through goats, e.g. caprinized rinderpest vaccine. In highly susceptible cattle this vaccine may cause significant reactions and lapinized vaccines are preferred.

core v. one that should always be included in the basic immunization program for the species.

dead v. inactivated vaccine; one with organisms that have been killed.

DNA v. DNA sequences that code for immunogenic proteins located in appropriately constructed plasmids which include strong promoters, which when injected into an animal are taken up by cells and the immunogenic proteins are expressed and elicit an immune response. No vaccines of this type are licensed and concerns about safety have not been resolved.

heterotypic v. one developed from a virus that is antigenically distinct but related to that causing the disease for which the animal is being immunized, e.g. measles vaccine used to protect dogs from canine distemper.

homotypic v. one developed from the same virus as that causing the disease the animal is being immunized against.

human diploid cell v. an inactivated rabies vaccine made from rabies virus grown on human embryo lung fibroblast cells.

inactivated v. see dead vaccine (above).

killed virus (KV) v. see dead vaccine (above).

live v. a vaccine prepared from live, usually attenuated, microorganisms.

v. lymph material containing vaccinia virus collected from vaccinial vesicles of inoculated calves; used for active immunization against smallpox.

mixed v. see mixed bacterial vaccine.

modified live virus (MLV) v. see attenuated vaccine (above).

polyvalent v. one prepared from more than one strain or species of microorganisms.

recombinant v. one created by recombinant DNA technology.

subunit v. one containing only specific antigenic proteins of the infectious agent.

synthetic peptide v. using synthetic short peptides which correspond with major epitopes of viral proteins to elicit a protective antibody response.

vectored v. use of viruses or bacteria as vectors to carry selected genes from another pathogen for immunization.

vaccinia [vak-sin’e-] the vaccinia virus; a laboratory generated virus, antigenically related to the cowpox virus, that causes a lesion on the teat skin of affected cows. It is indistinguishable from cowpox lesions and used to be used to vaccinate humans against smallpox.

vaccinial [vak-sin’e-l] pertaining to or characteristic of vaccinia.

vacciniform [vak-sin’-form] resembling vaccinia.

vacciniola generalized vaccinia.

vaccinology the study of vaccines and the technology associated with vaccine development. Includes the preparation and testing of vaccines, testing the animal’s immune response to the vaccine and the study of outcome against challenge. Advances in immunology, molecular biology, microbiology and biochemistry allow new directions for vaccine development strategies including the application of genetic engineering and proteomics.

reverse v. whole genome sequencing of pathogenic microorganisms to identify potential vaccine candidates without the need to cultivate the pathogens.

vaccinotherapy [vak“s-no-ther’-pe] therapeutic use of vaccines.

Vacor a single dose rodenticide that acts as an antagonist of B vitamins, particularly nicotinamide; useful against warfarinresistant rodents. Poisoning causes vomiting, abdominal pain and weakness. Called also pyriminil.

vacuolar [ak“u-o’lr] containing, or of the nature of, vacuoles.

vacuolated [vak’u-o-lāt“d] containing vacuoles.

vacuolation [vak“u-o-la’shn] the process of forming vacuoles; the condition of being vacuolated.

vacuole [vak’u-ōl] a space or cavity in the cytoplasm of a cell.

contractile v. a small fluid-filled cavity in the cytoplasm of certain unicellular organisms; it gradually increases in size and then collapses; its function is thought to be respiratory and excretory.

vacuolization [vak“u-o-l-za’shn] vacuolation.

Vacutainer® a registered brand of evacuated tubes for collection of venous blood. The tubes are designed to fill with a predetermined volume of blood by vacuum and the stoppers are color coded according to the coagulant or anticoagulant they contain and the analyses to be conducted. See blood collection tubes.

vacuum [vak’ūm] a space devoid of air or other gas.

v. collection use of a handheld vacuum to recover ectoparasites from the coat of animals.

v.-dehydrated freed of moisture while in a vacuum. Used in the packaging of food.

v. gauge pressure gauge in a milking machine which indicates the level of vacuum in the system.

v. pack meat or other perishable food is packed in a tightly sealed bag made of copolymers with polyvinyldene chloride and a low vacuum created. A bag made of nylon–polythene laminate is used for bags that are heat-sealed and a high vacuum created. The pack is then frozen for storage or shipment.

v. pressure used as the basis of the modern milking machine; the negative pressure is generated by a vacuum pump and transmitted through metal and rubber pipes to the teat cups and then to the teats; the continuous basic pressure is what keeps the teat cups on the teats; the periodic fluctuations is what causes the squeezing of the teat walls and the expulsion of the milk from the teats.

vagal [va’gl] pertaining to the vagus nerve.

v. attack see vasovagal attack.

v. maneuver pressure on the carotid sinus or eye to terminate supraventricular tachycardia. Used both diagnostically and therapeutically. Slowing a tachycardia may permit more details to become apparent on an electrocardiogram.

vagina [v-ji’n] 1. any sheath or sheathlike structure. 2. the canal in the female that runs from the vestibule in the external genitalia (vulva) to the cervix uteri.

v. bulbi (1) see Tenon’s capsule.

artificial v. a device used in the collection of semen from male animals. The usual construction is of a rigid external tube lined by a flexible, thin rubber sleeve. Water at body temperature is introduced between the tube and the sleeve so as to achieve a spongy warm cavity which is lubricated with inert material. A rubber cone, terminating in a graduated plastic or glass collecting tube, is placed over the distal end of the device which is then ready to use.

v. carotica (1) the fascial sheath surrounding the common carotid artery and also containing the internal jugular vein and vagus nerves. Called also carotid sheath.

double v. a congenital anomaly in which the embryogenesis of the vagina is associated with incomplete fusion of the caudal parts of the paired müllerian ducts. It is a normal feature of most marsupials. Called also septate vagina, vagina duplex.

external v. (1) of the optic nerve fascial sheath around the optic nerve and an extension of the dura mater. Called formally vagina externa n. optici.

pneumo-v. see pneumovagina.

sunken v. a condition seen in older mares in which the vagina falls forward, resulting in pooling of urine and vaginal secretions and pneumovagina.

vaginal pertaining to the vagina, the tunica vaginalis testis, or to any sheath.

v. anulus see anulus vaginalis.

v. aplasia manifested by imperforate hymen or residual strands of hymen. See imperforate hymen.

v. aspiration use of a suction apparatus to collect a sample of vaginal fluid for culture, cytological or immunological examination.

v. biopsy collection of a sample of mucosa by a pinch biopsy instrument for histopathological examination.

v. constriction inherited defect in Jersey cows combined with anal constriction, sometimes with rectovaginal fistula.

v. cyclic changes see vaginal cytology (below).

v. cysts see Gartner’s ducts, Bartholin’s glands.

v. cystocele the urinary bladder is lying on the floor of the vagina; the displacement has been via the urethra by eversion or via a tear in the floor of the vagina.

v. cytology cyclic changes in the exfoliated epithelial cells of the vaginal mucosa occurring synchronously with the stages of the estrous cycle; collection of samples by the use of a swab and laboratory examination of a smear is a useful aid in determining the most appropriate time to mate a bitch.

v. fornix see vaginal fornix.

v. hypertrophy see vaginal prolapse.

v. hypoplasia segmental see müllerian duct aplasia.

v. inflammation see vaginitis (1).

v. neoplasm include papilloma, sarcoma, leiomyoma.

v. process an outpocketing of the peritoneum into the gubernaculum at the site of the future inguinal canal in the male fetus; becomes the tunica vagina of the adult.

v. prolapse see vaginal prolapse.

v. retainer see bearing retainer.

v. ring see anulus vaginalis.

v. rupture occurs during mating, dystocia, insemination, or by sadistic or malicious trauma. Results in peritonitis or cellulitis of the pelvic fascia.

v. smear examination of the cells in a smear is used as an aid in predicting the time of ovulation, which may be useful in selecting the optimal date for breeding.

v. stricture cicatricial contraction after traumatic injury.

v. tunic the double peritoneal fold which encloses the spermatic cord and the testis; made up of a visceral layer which is adherent to the testis and cord, and a parietal layer which lines the scrotum and the inguinal canal.

v. vestibule entrance to the vagina enclosed between the lips of the vulva, the labia minor. Connects the vagina at the external urethral orifice to the external genital opening; develops from the embryonic urogenital sinus.

v. wash irrigation of the vagina with sterile saline can be used to recover cells, which are stained and examined microscopically to monitor estrus.

vaginalectomy vaginectomy.

vaginalitis [vaj“-n-li’tis] inflammation of the tunica vaginalis testis; periorchitis.

vaginate [vaj’-nāt] enclosed in a sheath.

vaginectomy [vaj“-nek’t-me] 1. resection of the tunica vaginalis testis. 2. excision of the vagina.

vaginismus [vaj“-niz’ms] painful spasms of the muscles of the vagina.

vaginitis [vaj“-ni’tis] 1. inflammation of the vagina; colpitis. 2. inflammation of a sheath.

adhesive v. that in which ulceration and exfoliation of the mucosa result in adhesions of the membranes.

contagious v. see infectious pustular vulvovaginitis, epivag.

granular v. spherical, 1 mm diameter nodules on the vulvar mucosa of the cow and the penile skin of the bull. Appears to be a nonspecific hyperplasia of lymphoid tissue, but linked anecdotally with Mycoplasma spp. Called also granular vulvovaginitis.

pustular v. see infectious pustular vulvovaginitis.

vaginoabdominal [vaj“-no-ab-dom’-nl] pertaining to the vagina and abdomen.

vaginocele [vaj’-no-sēl“] colpocele; vaginal hernia.

vaginofixation [vaj“-no-fik-sa’shn] vaginopexy; colpopexy.

vaginography [vaj“-nog’r-fe] radiography of the vagina using a contrast agent. Retrograde passage of the contrast agent can be used to demonstrate ectopic ureters in bitches.

vaginolabial [vaj“-no-la’be-l] pertaining to the vagina and labia.

vaginomycosis [vaj“-no-mi-ko’sis] any fungal disease of the vagina.

vaginopathy [vaj“-nop’-the] any disease of the vagina.

vaginoperineal [vaj“-no-per“-ne’l] pertaining to the vagina and perineum.

vaginoperineorrhaphy [vaj“-no-per“-ne-or’-fe] suture of the vagina and perineum; colpoperineorrhaphy.

vaginoperineotomy [vaj’-no-per“-ne-ot’-me] incision of the vagina and perineum.

vaginoperitoneal [vaj“-no-per“-to-ne’l] pertaining to the vagina and peritoneum.

vaginopexy [vaj’-no-pek“se] colpopexy; vaginofixation; suturing of the vagina to the abdominal wall in cases of vaginal relaxation.

vaginoplasty [vaj’-no-plas“te] colpoplasty; plastic repair of the vagina.

vaginoscope [vaj’-no-skōp] illuminated tubular instrument designed for examining the interior of the vagina. A common alternative is to use a vaginal speculum and a flashlight.

vaginoscopy [vaj“-nos’k-pe] viewing of the vaginal lining with a vaginoscope.

vaginotomy [vaj“-not’-me] colpotomy; incision of the vagina.

vaginourethrocystogram a contrast enhanced retrograde radiological study in which the vagina, urethra and urinary bladder are highlighted by the injection of a water-soluble iodine-based contrast agent into the vagina via a Foley catheter.

vaginourethrography radiography of the vagina and urethra. Contrast medium is introduced through a catheter into the vagina until it overflows into the urethra. Used in the diagnosis of lower urinary tract disease in bitches.

vaginovesical [vaj“-no-ves’-kl] pertaining to the vagina and bladder.

vagolysis [va-gol’-sis] surgical destruction of the vagus nerve.

vagolytic [va“go-lit’ik] having an effect resembling that produced by interruption of impulses transmitted by the vagus nerve; parasympatholytic.

v. agents includes atropine sulfate, glycopyrrolate, propantheline, isopropamide.

vagomimetic [va“go-m-met’ik] having an effect resembling that produced by stimulation of the vagus nerve.

vagosympathetic trunk [va“go-sim“p-thet’ik] the combined vagus nerve and the sympathetic trunk, invested in a common fascial sheath in the neck. In cats the two nerves remain separate.

vagotomy [va-got’-me] interruption of the impulses carried by the vagus nerve or nerves.

vagotonia [va“go-to’ne-] irritability of the vagus nerve.

vagotonin a preparation of hormone from the pancreas that increases vagal tone, slows the heart, and increases the store of glycogen in the liver.

vagotropic [va“go-tro’pik] having an effect on the vagus nerve.

vagovagal [va“go-va’gl] arising as a result of afferent and efferent impulses mediated through the vagus nerve.

vagus [va’gs] the tenth cranial nerve. For vagus nerve, see Table 14.

v. indigestion of cattle is the result of damage to branches of the vagus nerve which supply the rumenoreticulum, or to tension receptors in the wall of the reticulum. The two identified malfunctions are pyloric achalasia and reticulo-omasal achalasia (omasal transport failure). The clinical picture includes distention of the rumen or abomasum causing visible distention of the abdomen, emaciation and the passage of small amounts of pasty feces. Ruminal motility may be increased or decreased.

v. nerve signs dysfunction manifested by paralysis of pharynx, larynx, causing dysphagia, regurgitation through the nose, dyspnea, hypomotility of gastrointestinal tract.

Val valine.

valacyclovir [val“a-si’klo-vir] a prodrug of acyclovir with similar antiviral activity; toxic in cats because of fatal hepatic and renal necrosis.

valency, valence [va’ln-se, va’lens] 1. the numerical measure of the capacity to combine; in chemistry, an expression of the number of atoms of hydrogen (or its equivalent) that one atom of a chemical element can hold in combination, if negative, or displace in a reaction, if positive. 2. in immunology, an expression of the number of antigenic determinants with which one molecule of a given antibody can combine.

valerian [v-lēr’e-n] see Valeriana.

Valeriana a genus of herbaceous plants providing second class forage for livestock. Has a fleshy root containing valeric acid. V. officinalis is used for extraction of commercial valeric acid.

valgus [val’gs] [L.] bent outward; twisted; denoting a deformity in which the angulation is away from the midline of the body, as in coxa valga.

valine (Val) [va’lēn, val’ēn] a naturally occurring amino acid.

valinemia [val“in-e’me-] hypervalinemia; elevated concentration of valine in the blood and urine.

valinomycin ionophore consisting of a cyclic trimer of tetrapeptides. Specifically transports potassium ions across cell membranes. Inhibitor of oxidative phosphorylation due to its action in antagonizing the proton motive force.

vallate [val’āt] having a wall or rim; rim-shaped. See also vallate papilla.

V-1: Bilateral carpal valgus deformity in a foal.

From Bassert JM, McCurnin DM, McCurnin’s Clinical Textbook for Veterinary Technicians, 7th Edition. Saunders, 2010.

vallecula [v-lek’u-l] pl. valleculae [L.] a depression or furrow.

v. cerebelli a large groove on the ventral cerebellum, in which the medulla oblongata is lodged.

v. epiglottica the depressions on either side of the median glossoepiglottic fold.

v. sylvii a depression made by the fissure of Sylvius at the base of the brain. Called also lateral cerebral fossa and (formally) vallecula lateralis cerebri.

v. unguis the sulcus of the matrix of the nail.

Vallée’s vaccine an historical vaccine composed of living Mycobacterium avium subspecies paratuberculosis organisms in a paraffin oil–pumice stone vehicle; once used as a prophylactic against Johne’s disease in cattle.

valley fever coccidioidomycosis.

valnemulin an antibiotic in the pleuromutilin class, used in the treatment of enteric infections, especially swine dysentery, and enzootic pneumonia of pigs.

valone [val’ōn] an anticoagulant rodenticide. One of the indandione compounds with actions similar to that of warfarin.

valor a rodenticide no longer marketed because of toxicity in horses causing dehydration, abdominal pain, hindlimb weakness, inappetence, fishy smell in urine. Called also N-3-pyridyl methyl N¹-p-nitrophenyl urea.

valproic acid [val-pro’ik] an anticonvulsant drug.

Valsalva maneuver [vahl-sahl’v] a forcible expiratory effort in combination with a closed glottis as occurs in coughing.

valsiekte [Af.] ‘falling disease’, characterized by myelomalacia, ataxia caused by Chrysocoma ciliata.

value [val’u] a measure of worth or efficiency; a quantitative measurement of the activity, concentration, etc., of specific substances.

absolute v. the size of an observation or measurement regardless of its sign.

expected v. an estimate of the value of a population parameter, which would be achieved by sampling an infinite number of times.

normal v’s the range in concentration of specific substances found in normal healthy tissues, secretions, etc. Called also reference interval.

valva [val’v] pl. valvae [L.] a valve.

valve [valv] 1. a membranous fold in a canal or passage that prevents backward flow of material passing through it. 2. a mechanical device to regulate the flow of liquid or gas from an area of higher pressure to one of lower pressure. 3. automatic valve which maintains a steady vacuum in the system of a mechanical milking machine.

Adam’s pressure reducing v. see reducing valve (below).

aortic v. see aortic valve.

atrioventricular v’s the valves between the right atrium and right ventricle (tricuspid valve) and the left atrium and left ventricle (mitral valve).

bicuspid v. mitral valve.

cardiac v’s valves that control flow of blood through and from the heart. See also aortic valve, mitral valve, pulmonary valve, tricuspid valve.

coronary v. a valve at entrance of the coronary sinus into right atrium.

flair v. a cardiac valve having a cusp that has lost its normal support (as in ruptured chordae tendineae) and flutters in the bloodstream.

ileocecal v., ileocolic v. see ileocecal valve.

nonreturn v. in anesthetic circuits, it prevents exhaled gas from returning to the patient.

portal v. regulates the amount of venous blood entering the avian kidney.

pressure reducing v. see reducing valve (below).

pyloric v. the exit from the stomach guarded by a sphincter muscle that supports a prominent fold of mucous membrane at the pyloric orifice.

reducing v. a special valve used on anesthetic machines and which reduces the pressure of the gas reaching the exit valve so that control of the flow is made easier. Called also regulator.

semilunar v’s valves made up of semilunar segments or cusps (valvulae semilunares), guarding the entrances into the aorta and pulmonary artery.

thebesian v. coronary valve.

valvotomy [val-vot’-me] incision of a valve.

valvula [val’vu-l] pl. valvulae [L.] a small valve; a single cusp of one of the semilunar valves of the heart.

valvular [val’vu-lr] pertaining to, affecting or of the nature of a valve.

v. disease interferes with the normal rate and smoothness of blood flow through the cardiac orifices. The creation of turbulence results in the appearance of palpable thrills and audible murmurs, stenosis and insufficiency causing congestive heart failure. See also chronic valvular heart disease (below) and names of cardiac valves.

chronic v. heart disease the most common heart disease in dogs, known also as endocardiosis and myxomatous valve degeneration. It affects most commonly the left atrioventricular (mitral) valve and the prevalence is higher in small breeds with an early age of onset in Cavalier King Charles spaniels. There is progressive myxomatous degeneration with thickening and nodular changes in the free edge and base of the valve(s); cordae tendinae are also affected. Usually slowly progressive deformation results in valvular incompetence with regurgitation, left ventricular volume overload and ventricular failure. Mitral valve prolapse is a common complication. The cause is unknown, but there appears to be an inherited component.

v. incompetence the valves do not close completely and when pressure is exerted on them blood leaks back through causing inefficient forward movement of the blood and turbulent flow leading to the development of cardiac murmurs.

v. stenosis narrowing of the lumen of the aperture through which the blood passes causing back pressure in the venous or pulmonary circuits. The clinical manifestations include cardiac murmurs and thrills and congestive heart failure. See also stenosis.

valvulitis [val“vu-li’tis] inflammation of a valve, especially of a valve of the heart.

valvuloplasty [val’vu-lo-plas“te] plastic repair of a valve, especially a valve of the heart.

balloon v. use of an intracardiac catheter with an inflatable balloon to dilate stenotic cardiac valves. Used in the correction of pulmonic stenosis, and less often aortic stenosis, in dogs.

valvulotome [val’vu-lo-tōm“] an instrument for cutting a valve.

valvulotomy [val“vu-lot’-me] valvotomy.

balloon v. see balloon valvuloplasty.

van den Bergh test, reaction a test which differentiates between conjugated and unconjugated bilirubin in serum and assists in the differentiation between biliary or regurgitation hyperbilirubinemia, retention or hemolytic hyperbilirubinemia, or combined hyperbilirubinemia or jaundice. There are many variants of the basic test and the interpretation of them differs markedly between the species.

Van der Waals forces the relatively weak, short-range forces of attraction existing between atoms and molecules, which results in the attraction of nonpolar organic compounds to each other (hydrophobic bonding).

vanadium (V) [v-na’de-m] a chemical element, atomic number 23, atomic weight 50.942. See Table 4. Its salts have been used in treating various diseases.

v. poisoning in humans poisoning is usually by inhalation causing respiratory irritation and pneumonia. In livestock, poisoning is by ingestion of contaminated pasture, usually from mining pollution, and manifested by stunted growth, pot belly, submandibular edema, diarrhea, incoordination and oliguria.

vanadiumism [v-na’de-m-iz-m] poisoning by vanadium.

vancomycin [van“ko-mi’sin] a narrow-spectrum antibiotic produced by Streptomyces orientalis, highly effective against gram-positive bacteria; it is commonly reserved for use against serious infections caused by penicillinase-resistant staphylococci and enterococci. The toxic effects are quite severe and include damage to the eighth cranial (vestibulocochlear) nerve and renal disorders.

v. resistant enterococcus (VRE) a group of multi-drug resistant bacteria associated with high mortality in humans.

vane [vān] the membranous or main part of the contour feather in birds as distinct from the shaft. It consists of the barbs held together by the interlocking barbules. Called also vexillum.

Vangueira pygmaea Pachystigma pygmaeum.

vanillylmandelic acid [v-nil’l-mn-del’ik] an excretory product of the catecholamines found in the urine; used as a test in the diagnosis of phaeochromocytoma.

van’t Hoff’s law the velocity of chemical reactions is increased twofold or more for each rise of 10°C in temperature.

vapor [va’pr] steam, gas or exhalation.

Vapor vaporizer a type of temperature- and flow-compensating precision vaporizer for specific inhalation anesthetic agents.

vaporization [va“pr--za’shn] 1. the conversion of a solid or liquid into a vapor without chemical change; distillation. 2. treatment by vapors; vapotherapy.

vaporize [va’pr-īz] to convert into vapor or to be transformed into vapor.

vaporizer [va“por-īz’r] part of the apparatus used to deliver volatile anesthetic agents to patients. It is the vessel that vaporizes the liquid anesthetic and adds it to the flow of gas to the patient. The objective of them all is to deliver a suitable, accurately calibrated, quantity of anesthetic at all times and under all conditions. See also EMO vaporizer, Dräger vaporizer, Goldman vaporizer, Vapor vaporizer.

bubble v., bubble through v. the carrier gas is dispersed through the anesthetic agent, usually through a diffuser, to form the anesthetic mixture to be inhaled. An example is the copper kettle vaporizer.

calibrated v. one with graduations to measure accurately the concentration of anesthetic vapor delivered.

wick v. carrier gas moves over the surface of the liquid anesthetic. Sheets of pliable material are used as wicks to increase the surface area. Examples are Vapor and ‘tec’ (Fluotec, Fortec) vaporizers.

vapotherapy therapeutic use of steam, vapor or spray.

VA/Q see ventilation:perfusion ratio.

Vaqueta see Thiloa glaucocarpa.

Vaquez–Osler disease [vah-ka’- ōs’lr] primary polycythemia.

var. variety.

Varess needle used for the initial insufflation of the abdominal cavity with gas (carbon dioxide) for laparoscopy, prior to placement of any other equipment into the abdominal cavity. The needle consists of a sharp outer cannula and blunt hollow stylet through which the gas may pass.

Varestrongylus see Bicaulus.

variability [var“e--bil’-te] the state of being variable.

variable [var’e--bl] 1. any type of measurement, quantitative or qualitative, of which a series of individual observations is made so that it has, as a principal characteristic, the potential for variability. 2. has the quality of variability.

v. agent an agent in the cause of a disease which is capable of variation in intensity, e.g. weather, as contrasted to one that is not variable, e.g. Salmonella dublin.

concomitant v’s in experimental design these refer to factors that affect the dependent variable, but are not themselves influenced by the treatment (e.g. age of animal). The effect of concomitant variables can be removed by suitable experimental design or by including them in the model.

continuous v. one in which all values within a given range are possible, e.g. birth weights of calves.

v. costs costs which vary with the dimensions of the activity. Includes seed, fertilizer, teat dip, worm drench. Called also direct costs. See also fixed costs.

dependent v. 1. in statistics the variable predicted by a regression equation. 2. a variable which depends on other variables for its value.

discontinuous v. see discrete variable (below).

discrete v. one in which the possible values are not on a continuous scale, e.g. the number of sheep in a flock.

endogenous v. dependent variable.

exogenous v. independent or predetermined variable.

independent v. one not dependent on other variables but capable of affecting dependent variables, thus an input variable.

spatial v. a measurement relating to area or location.

temporal v. one relating to chronological time.

variable region the N-terminal portion of heavy and light chains of immunoglobulin molecules in which the amino acid sequence varies as a consequence of somatic mutation and recombination during ontogeny of B lymphocytes and also occurring after antigen exposure. The variable amino acid sequence which provides more than 10⁷ different antibody molecules is responsible for the antigen-binding specificity.

variance [var’e-ns] one of the measures of the dispersion of data; the mean squared deviation of a set of values from the mean.

additive genetic v. that portion of phenotypic variance which is due to the additive effect of genes (V_A).

analysis of v. a statistical method for comparing values, expressed in terms of means or variance, of one or more variables in several subgroups of a population. Called also anova.

environmental v. that portion of the phenotypic variance caused by differences in the environment to which the individuals have been exposed.

non-additive genetic v. that portion of phenotypic variance which is due to epistatic interactions (V_I) and dominance deviations (V_D).

non-genetic v. that portion of phenotypic variance which is due to non-genetic effects such as environment (V_E).

phenotypic v. a measure of the extent to which individuals vary in their phenotype (V_P). V_P = V_A + V_D + V_I + V_E.

v. ratio distribution see f distribution.

variant [var’e-nt] an organism or tissue that is different from the majority of the population but is still sufficiently similar to the common mode to be considered to be one of them, e.g. a variant strain of classical swine fever (hog cholera) virus.

variation [var“e-a’shn] divergence among individual animals of a group. The differences in the morphology or function of an organ or organism, are small enough to stay within the variability of the type organism or organ.

varicella-zoster virus [var“-sel’] a member of the family Herpesviridae, genus Varicellovirus that causes chicken pox in humans early in life and herpes zoster (shingles), as a reactivation of latent virus, in later life; also infects gorillas, orangutans and chimpanzees.

Varicellovirus a genus in the subfamily Alphaherpesvirinae.

varices [vār’-sēz] [L.] plural of varix.

variciform [var-is’-form] resembling a varix; varicose.

varicoblepharon [var“-ko-blef’-ron] a varicose swelling of the eyelid.

varicocele [var’-ko-sēl“] varicosity of the pampiniform plexus of the spermatic cord, forming a swelling in the scrotal neck that feels like a ‘bag of worms’.

varicocelectomy [var“-ko-s-lek’t-me] excision of a varicocele.

varicomphalos [var“-kom’f-ls] a varicose tumor of the umbilicus.

varicose [var’-kōs] of the nature of or pertaining to a varix; unnaturally and permanently distended (said of a vein); variciform.

v. scrotal tumor benign vascular proliferation in dogs; resembles cavernous hemangioma.

v. veins are uncommonly found in animals except on the scrotum of old bulls, in the dorsal wall of the vagina in mares and on the prepuce in stallions. May also be associated with arteriovenous fistulae.

varicosity [var“-kos’-te] 1. a varicose condition; the quality or fact of being varicose. 2. a varix, or varicose vein.

varicotomy [var“-kot’-me] excision of a varix or of a varicose vein.

varicula [v-rik’u-l] a varix of the conjunctiva.

variety [v-ri’-te] a taxonomic subcategory of a species.

variegated tick see Amblyomma variegatum.

variola [v-ri’o-l] a viral disease of humans and primates characterized by fever, rash and scab formation. Called also smallpox.

varix [var’iks] pl. varices [L.] an enlarged, tortuous vein, artery or lymphatic vessel.

aneurysmal v. a markedly dilated tortuous vessel; sometimes used to denote a form of arteriovenous aneurysm in which the blood flows directly into a neighboring vein without the intervention of a connecting sac.

arterial v. a racemose aneurysm or varicose artery.

lymph v., v. lymphaticus a soft, lobulated swelling of a lymph node, due to obstruction of lymphatic vessels.

varization a surgical procedure that decreases the angle of inclination of a part.

v. femoral osteotomy a surgical procedure involving an intertrochanteric osteotomy and removal of a bone wedge to create a varus deviation of the femoral head and neck. Used to increase hip stability in dogs with hip dysplasia.

varkoor see Zantedeschia aethiopica.

Varnell gag a gag similar to the Hitching gag, except that the crossbars are rounded, and usually covered with leather or rubber, and fit into the interdental space.

varnish tree Aleurites moluccana.

varolian [v-ro’le-n] pertaining to the pons varolii.

varroosis a disease of the honey bee (Apis mellifera) caused by the mite Varroa destructor, which parasitizes bee larvae and adults causing developmental deformities, reduced life span and ultimately destruction of the colony or hive. A disease notifiable to the OIE (see Table 22).

varus [var’s] [L.] bent inward; denoting a deformity in which the angulation of the part is toward the midline of the body, as in coxa vara, genu varum.

V-2: Carpal varus deformity.

From Floyd AE, Mansmann, RA, Equine Podiatry. Saunders, 2008.

v. stress test adduction of the tibia while the femur is in a fixed position tests the integrity of the lateral collateral ligaments of

vas [vas] pl. vasa [L.] a vessel.

v. aberrans 1. a blind tube sometimes connected with the epididymis; a vestigial mesonephric tube. 2. any anomalous or unusual

v. afferentia vessels that convey fluid to a structure or part.

v. brevia short vessels such as the gastric arteries.

v. deferens the excretory duct of the testis which conveys spermatozoa from the tail of the epididymis to the pelvic urethra and which sometimes unites with the excretory duct of the seminal vesicle to form the ejaculatory duct; called also ductus deferens.

v. efferentia vessels that convey fluid away from a structure or part.

v. lymphatica lymphatic vessels.

v. recta straight vessels, such as the long U-shaped vessels arising from the efferent glomerular arterioles of juxtamedullary nephrons and which then supply the renal medulla.

v. vasorum the small nutrient arteries and veins in the walls of the larger blood vessels.

vasa [va’s] [L.] plural of vas.

vascular [vas’ku-lr] pertaining to blood vessels or indicative of a copious blood supply.

v. clamps see hemostatic forceps.

v. clip see clip (1).

v. disease see arteritis, phlebitis, lymphangitis, thrombosis, aneurysm, capillary fragility.

v. grafts see vascular conduit.

v. hemophilia von Willebrand disease.

v. malformation includes hamartoma, arteriovenous fistula, telangiectasia.

v. neoplasm listed elsewhere; these include hemangioma, hemangiosarcoma, hemangioendothelioma, hamartoma, telangiectasia, angiokeratoma, juvenile bovine angiomatosis, bovine cutaneous angiomatosis, varicose scrotal tumor, meningioangioma, lymphomatoid granulomatosis, lymphangioma, lymphangiosarcoma, glomangioma.

v. nevus irregular shaped, cutaneous mass, congenital, haircovered initially, subsequently hairless, usually 1–2 inches diameter in foals, may be inflamed, ulcerated; composed of densely packed blood vessels and bleed easily: most located on lower limbs; see also nevus.

v. occlusive syndrome complete occlusion of the vessel supplying blood to a part of the body causes temporary loss of function or death of the part, fall in temperature and change in color.

v. plaque a minor lesion in animals; manifested by slight thickening and wrinkling of the intima of the vessel over oval or elongated elevations.

v. pole the point on the renal glomerulus where the blood vessels enter and exit.

v. prosthesis see vascular conduit.

v. ring anomaly see vascular ring.

v. sinus transformation marked dilation of sinuses in lymph nodes because of blockage of drainage from the node.

v. stasis serious slowing, or complete cessation, of blood or lymph flow through vessels.

v. system the vessels of the body including aorta, arteries, arterioles, capillaries, venules, sinusoids, sinuses, veins, lymphatics.

v. tone the state of contractile tension in the vessel walls.

v. tumor see vascular neoplasm (above).

v. tunic of the eye; the uvea. Consists of the choroid, the ciliary body and iris.

vascularity [vas“ku-lar’-te] the condition of being vascular.

vascularization [vas“ku-lr--za’shn] the formation of new blood vessels in tissues.

vascularize [vas’ku-lr-īz] to supply with vessels.

vasculature [vas’ku-l-chr] 1. the vascular system of the body, or any part of it. 2. the supply of vessels to a specific region.

vasculitis [vas“ku-li’tis] inflammation of a vessel; common causes include allergic, immune-mediated. Histopathologically differentiable types include eosinophilic, lymphocytic. Called also angiitis.

leukocytoclastic v. see hypersensitivity angiitis.

V-3: Cutaneous vasculitis. Peripheral edema caused by vascular leakage associated with vasculitis.

From Medleau L, Hnilica KA, Small Animal Dermatology, 2nd Edition. Saunders, 2006.

necrotizing v. important feature of the Arthus reaction; damage to the endothelium results from deposition of immune complexes in the vessel wall, usually on the basement membrane of the endothelium. A form of necrotizing vasculitis is described in young adult Beagles, Bernese mountain dogs and German shorthaired pointers, associated with neurological signs. A genetic predispositon is suspected.

vasculopathy [vas“ku-lop’-the] any disorder of blood vessels.

familial cutaneous v. of German shepherd dogs an autosomal recessive genodermatosis characterized by swellings on the nose, ulcers and crusting on the ears, nasal planum and tail tip. The footpads are swollen, hypopigmented and sometimes ulcerated. There is joint swelling, fever and lymphadenopathy. The condition may follow vaccination in pups.

v. of Greyhounds see idiopathic cutaneous and renal glomerular disease.

vasectomized [v-sek’t-mīzd] subjected to vasectomy.

vasectomy [v-sek’t-me] excision of the vas (ductus) deferens, or a portion of it; bilateral vasectomy results in sterility.

Vaseline trademark for white petrolatum (USP), petroleum jelly.

vasey grass Paspalum urvillei.

Vasgotaspets see Swedish Vallhund.

vasiform [vas’-form] resembling a vessel.

vasitis [v-si’tis] inflammation of the vas (ductus) deferens.

vas(o)- word element. [L.] vessel, duct.

vasoactive [vas“o-ak’tiv] exerting an effect on the caliber of blood vessels.

v. intestinal peptide (VIP), v. intestinal polypeptide a peptide hormone that, in addition to its vasoactive properties, stimulates intestinal secretion of water and electrolytes, inhibits gastric secretion, promotes glycogenesis, causes hyperglycemia and stimulates secretion of pancreatic juice.

v. substances substances which cause constriction of blood vessels; substances which actively dilate vessels, rather than relax an existing vasoconstriction, should be included. See vasoconstrictor agents and vasodilator agents.

v. substances, endothelium-derived includes nitrous oxide, prostacyclin and other prostanoids, unnamed relaxing or constricting factors released as a result of a tissue insult, e.g. hypoxia or excessive stretch.

vasoconstriction [vas“o-kn-strik’shn] decrease in the caliber of blood vessels; may be general or local, e.g. pulmonary, peripheral.

vasoconstrictor [vas“o-kn-strik’tr] 1. causing constriction of the blood vessels. 2. a vasoconstrictive agent.

v. agents includes some prostaglandins, thromboxane A₂, leukotriene D₄, angiotensin II, vasopressin, neuropeptide Y, endothelin.

v. fibers adrenergic nerve fibers in the walls of all blood vessels except capillaries.

vasodepression [vas“o-de-presh’n] decrease in vascular resistance with hypotension.

vasodepressor [vas“o-de-pres’r] 1. having the effect of lowering the blood pressure through reduction in peripheral resistance. 2. An agent that causes vasodepression.

vasodilatation [vas“o-d-l-ta’shn] vasodilation.

vasodilation [vas“o-di-la’shn] a state of increased caliber of blood vessels.

vasodilator [vas“o-di’la-tr] 1. causing dilatation of blood vessels. 2. a nerve or agent that causes dilatation of blood vessels.

v. agents include prostaglandin E₂, prostacyclin, bradykinin, histamine, serotonin, vasoactive intestinal peptide, substance P, adenosine triphosphate, endothelium-derived relaxing factor.

vasoepididymography [vas“o-ep“-did“-mog’r-fe] radiography of the vas deferens and epididymis after injection of a contrast medium.

vasoepididymostomy [vas“o-ep“-did--mos’t-me] anastomosis of the vas (ductus) deferens and the epididymis.

vasoformative [vas“o-for’m-tiv] pertaining to or promoting the formation of blood vessels.

vasoganglion [vas“o-gang’gle-on] a vascular ganglion or rete.

vasogenic [va“zo-jen’ik] emanating from or pertaining to blood vessels.

v. circulatory failure see vasogenic shock.

vasography [va-zog’r-fe] radiography of the blood vessels.

vasohypertonic [vas“o-hi“pr-ton’ik] vasoconstrictor.

vasohypotonic vasodilator.

vasoinhibitor [vas“o-in-hib’-tr] an agent that inhibits vasomotor nerves.

vasoligation [vas“o-li-ga’shn] ligation of the vas (ductus) deferens.

vasomotion [vas“o-mo’shn] change in caliber of blood vessels.

vasomotor [vas“o-mo’tr] 1. having an effect on the caliber of blood vessels. 2. a vasomotor agent or nerve.

v. system the part of the nervous system that controls the caliber of the blood vessels.

vasoneuropathy [vas“o-n -rop’-the] a condition caused by combined vascular and neurological defect, resulting from simultaneous action or interaction of the vascular and nervous systems.

vasoneurosis [vas“o-n -ro’sis] angioneurosis.

vaso-orchidostomy anastomosis of the epididymis to the severed end of the vas (ductus) deferens.

vasoparesis [vas“o-p-re’sis] paralysis of vasomotor nerves.

vasopermeability [vas“o-pur“me--bil’-te] the permeability of a blood vessel; the extent to which a blood vessel is permeable.

vasopressin [vas“o-pres’in] a hormone secreted by cells of the hypothalamic nuclei and stored in the posterior pituitary for release as necessary; it stimulates contraction of the muscular tissues of the capillaries and arterioles, raising the blood pressure, and increases peristalsis, exerts some influence on the uterus, and influences resorption of water by the kidney tubules, resulting in concentration of urine. Its rate of secretion is regulated chiefly by the osmolarity of the plasma. Also prepared synthetically or obtained from the posterior pituitary of domestic animals; used as an antidiuretic. Called also antidiuretic hormone (ADH).

v. test see antidiuretic hormone response test.

vasopressor [vas“o-pres’r] 1. stimulating contraction of the muscular tissue of the capillaries and arteries. 2. a vasopressor agent.

vasopuncture [vas“o-punk’chr] surgical puncture of the vas (ductus) deferens.

vasoreflex [vas“o-re’fleks] a reflex of blood vessels.

vasorelaxation [vas“o-re-lak-sa’shn] decrease of vascular pressure.

vasorrhaphy suture of the vas (ductus) deferens.

vasosection [vas“o-sek’shn] the severing of a vessel or vessels, especially of the vasa deferentia (ductus deferentes).

vasosensory [vas“o-sen’sr-e] supplying sensory filaments to the vessels.

vasospasm [vas’o-spaz“m] spasm of blood vessels, decreasing their caliber.

vasostimulant [vas“o-stim’u-lnt] stimulating vasomotor action.

vasostomy [vas-os’t-me] surgical formation of an opening into the ductus (vas) deferens.

vasotocin [vas“o-to’sin] the normal antidiuretic hormone in birds. One of the hormones released by the avian posterior pituitary gland. Called also arginine vasotocin (AVT). Is also active in stimulating uterine contraction.

vasotomy [va-zot’-me] incision of the vas (ductus) deferens.

vasotonia [vas“o-to’ne-] tone or tension of the vessels.

vasotonic [vas“o-ton’ik] pertaining to, characterized by, or increasing vasotonia.

vasotrophic [vas“o-tro’fik] affecting nutrition through alterations of the caliber of the blood vessels.

vasotropic [vas“o-tro’pik] exerting an influence on the blood vessels, causing either constriction or dilatation.

vasovagal [vas“o-va’gl] vascular and vagal.

v. attack, v. syncope a transient vascular and neurogenic reaction in humans marked by pallor, nausea, sweating, bradycardia, and rapid fall in arterial blood pressure which, when below a critical level, results in loss of consciousness and characteristic electroencephalographic changes.

vasovasostomy [vas“o-va-zos’t-me] anastomosis of the ends of the severed vas (ductus) deferens.

vasovesiculectomy [vas“o-v-sik“u-lek’t-me] excision of the vas (ductus) deferens and seminal vesicle.

vastus [vas’ts] [L.] great.

VC vital capacity.

VCG vectorcardiogram.

VCI Veterinary Council of Ireland.

vCJD variant Creutzfeld-Jakob disease caused by the agent of bovine spongiform encephalopathy.

VCNZ Veterinary Council of New Zealand.

VCPR veterinarian-client-patient relationship.

VDH valvular disease of the heart.

veal in general terms means meat from young calves but there is no internationally acceptable definition of veal. The commonest starting point is 2 weeks of age. Any calves younger than that are considered to be too tasteless and uneconomical. White veal is from calves fed only on milk which necessarily limits their oldest permissible age. Most veal calves marketed at older than 12 weeks are fattened on grain. No roughage is fed and the calves are muzzled if they are allowed onto pasture. This kind of veal calf is grown out to produce a dressed carcass of 250– 300 lb. In some countries veal carcasses are allowed to cool down with their skins still on to prevent dehydration. It also causes a distinct and desirable souring of the meat. Some methods of housing and feeding veal calves raise concerns for animal welfare.

heavy v. calves fed on hard feed, weigh >400 lb (182 kg), aged >3 weeks. Called also Western veal calves.

Western v. calves see heavy veal calves (above).

vealer young calf destined to be marketed as veal.

v. feedlot calves are confined for a short period and fed intensively in a lot, usually under shelter.

vection [vek’shn] the carrying of disease germs from an infected animal to a well animal.

vectis short metal rod with a loop at each end used in canine and feline obstetrics. The loops are of a size that they will engage the cranium or the front of the head in long-nosed breeds and permit traction or rotation of the fetus.

vector [vek’tr] 1. a carrier, especially the animal (usually an arthropod) which transfers an infective agent from one host to another, e.g. the tsetse fly, which carries trypanosomes from animals to humans, dogs, bats and other animals that transmit the rabies virus. In molecular biology, a DNA molecule which serves to transfer DNA into a host cell. 2. a quantity possessing magnitude, direction and sense (positivity or negativity).

biological v. an arthropod vector in whose body the infecting organism must develop or multiply before becoming infective to the recipient individual.

cloning v. a DNA molecule used to transfer an inserted DNA segment into a host cell. Includes other viruses, phages and bacterial plasmids. Called also cloning vehicle.

v. data representation see vector data representation.

mechanical v. an arthropod vector that physically transmits the infective organisms from one host to another but is not essential to the life cycle of the parasite.

shuttle v’s vectors which contain both prokaryotic and eukaryotic replication signals, thus allowing replication of the vector in both kinds of cells.

targeting v. a vector carrying a DNA sequence that is able to take part in a specified chromosomal crossover in the host.

vectorcardiogram [vek“tr-kahr’de-o-gram“] the record, usually a photograph, of the loop formed on the oscilloscope in vectorcardiography.

vectorcardiography [vek“tr-kahr“de-og’r-fe] the registration, usually by formation of a loop on an oscilloscope, of the direction and magnitude (vector) of the moment-to-moment electromotive forces of the heart during one complete cycle.

vecuronium [vek“u-ro’ne-m] a derivative of pancuronium, used as a short-acting neuromuscular blocking agent.

vedaprofen a propionic acid nonsteroidal anti-inflammatory agent used in horses and dogs.

VEE Venezuelan equine encephalomyelitis.

vegan [ve’gn] a person who advocates and consumes a purely vegetarian diet and does not use animal products in clothing or use any other animal-derived product.

vegetable [vej’-t-bl] 1. pertaining to or derived from plants. 2. any plant or species of plant, especially one cultivated as a source of food.

v. drugs derived from plants; includes alkaloids, glycosides, resins, gums and oils.

v. matter base residue after dissolving wool in a sample; a measure of the contamination of the wool.

v. oil oil derived from plants. Commercially used oils include peanut, linseed, sesame, cottonseed and castor. A separate group is the volatile oils including oil of turpentine, eucalyptus, peppermint and oil of cloves (eugenol). Animal oils are irritating to tissue and their accidental inhalation almost always causes a serious aspiration pneumonia. Vegetable oils are virtually nonpathogenic.

vegetal [vej’-tl] 1. pertaining to plants or a plant. 2. vegetative.

vegetarian [vej“-tar’e-n] a person who eats no meat, eggs or dairy food.

lacto-ovo v. a person who eats no meat, but does consume dairy products and eggs.

vegetation [vej“-ta’shn] 1. any plant-like fungoid neoplasm or growth; a luxuriant fungus-like growth of pathological tissue. 2. plant growth.

vegetative [vej’-ta“tiv] 1. concerned with growth and nutrition. 2. functioning involuntarily or unconsciously. 3. resting; denoting the portion of a cell cycle during which the cell is not replicating. 4. pertaining to plants. 5. asexual reproduction.

inherited v. dermatosis see dermatosis vegetans.

v. nervous system autonomic nervous system.

v. state in neurological assessment, the animal is in a coma, but can be aroused. There is brainstem activity but cortical responses are absent.

vehicle [ve’-kl] 1. a transporting agent, especially the component of a medication (prescription) serving as a solvent or to increase the bulk or decrease the concentration of the mixture. 2. any medium through which an impulse is propagated.

cloning v. see cloning vector.

veil [vāl] 1. a covering structure. 2. a caul or piece of amniotic sac occasionally covering the face of a newborn animal.

v. cell fibroblast-like cells which surround small vessels in the dermis.

Veillonella small, gram-negative anaerobic cocci that are part of the normal microflora in the mouth, intestine, respiratory system of animals.

vein [vān] a vessel through which blood passes from various organs or parts back towards the heart, in the systemic circulation carrying blood that has given up most of its oxygen. Veins, like arteries, have three coats, an inner, middle and outer, but the coats are not so thick and they collapse when the vessel is cut. Many veins, especially the superficial, have valves formed of reduplication of their lining membrane. For a complete list of the named veins of the body, see Table 15.

afferent v’s veins that carry blood to an organ.

allantoic v’s paired vessels that accompany the allantois, growing out from the primitive hindgut and entering the body stalk of the early embryo.

cardinal v’s the major veins within the early embryo that include the pre- and postcardinal veins and the ducts of Cuvier (common cardinal veins).

emissary v. a vein escaping from a chamber or organ such as one passing through a foramen of the skull and draining blood from a cerebral sinus into a vessel outside the skull.

postcardinal v’s paired vessels in the early embryo that return blood from regions caudal to the heart.

precardinal v’s paired venous trunks in the embryo cranial to the heart.

pulp v’s vessels draining the venous sinuses of the spleen.

subcardinal v’s paired vessels in the embryo, replacing the postcardinal veins and persisting to some degree as definitive vessels.

sublobular v’s tributaries of the hepatic veins that receive the central veins of hepatic lobules.

supracardinal v’s paired vessels in the embryo developing later than the subcardinal veins and persisting chiefly as the lower segment of the inferior vena cava.

thebesian v’s smallest cardiac veins: numerous small veins arising in the muscular walls and draining independently into the cavities of the heart, and most readily seen in the atria.

trabecular v’s vessels coursing in splenic trabeculae, formed by tributary pulp veins.

varicose v’s permanently dilated, tortuous veins. The milk vein of a lactating cow is a normal varicose vein. See varicose veins.

vitelline v’s veins that return the blood from the yolk sac to the primitive heart of the early embryo.

vela [ve’l] plural of velum.

velamen [ve-la’mn] pl. velamina [L.] a membrane, meninx or velum.

velamentous [vel“-men’ts] membranous and pendent; like a veil.

veldt sickness see heartwater.

vell abattoir term for abomasum of milk-fed calf used for the preparation of rennet for junket tablets.

Velleia Australian plant genus in the family Goodeniaceae; contains an unidentified toxin; causes dyspnea, depression in sheep. Includes V. connata, V. discophora (cabbage poison), V. panduriformis (pindan poison), V. paradoxa.

vellein coumarin glycoside of uncertain toxicity in Velleia discora.

vellus [vel’s] 1. fine hairs that appear on human skin after the lanugo hairs are cast off. 2. any fine, downy hair.

velogenic [ve“lo jen’ik] 1. a host–parasite relationship in which the parasite dominates and the host frequently dies. 2. highly virulent, e.g. velogenic Newcastle disease virus, as opposed to lentigenic and mesogenic which are low and intermediate virulence strains, respectively.

velometer an instrument that measures air movement velocity in meat storage facilities. A variation on the anemometer.

velopharyngeal [ve“lo-f-rin’je-l] pertaining to the velum palatinum (soft palate) and pharynx.

Velpeau sling see Velpeau sling.

velum [ve’lm] pl. vela [L.] a covering structure or veil.

v. abomasicum two folds on either side of the omasoabomasal orifice.

v. interpositum the membranous roof of the third ventricle of the brain.

medullary v. one of the two portions (rostral medullary velum and caudal medullary velum) of the white matter of the hindbrain that form the roof of the fourth ventricle.

palatine v., v. palatinum soft palate.

v. uteri see intracornual frenulum.

velvet see antler.

v. disease a disease of aquariumfish caused by the flagellate protozoan Oodinium limnecicum. Affected fish develop a varnished look caused by a very heavy infestation of the protozoa on the skin and die within a few days. Called also freshwater velvet, gold dust disease and rust disease.

v. grass see Holcus lanatus.

vena [ve’n] pl. venae [L.] vein. See also Table 15.

caudal v. caval syndrome vena caval thrombosis (below).

cranial v. caval thrombosis syndrome in which pulmonary abscesses cause cough, hyperpnea and poor exercise tolerance. Commonly results from jugular vein thrombosis following intravenous therapy using this site. Jugular vein engorgement and local edema may also occur. See also caval syndrome.

cranial v. caval venipuncture a technique for blood sample collection in pigs; a needle is inserted into the cranial vena cava near the thoracic inlet.

v. cava one of the large vessels emptying venous blood into the right atrium; includes cranial and caudal venae cavae.

v. cava spontaneous rupture recorded as a cause of sudden death in horses.

v. caval hiatus see vena cava foramen.

v. caval syndrome see caval syndrome.

v. caval thrombosis thrombosis of the caudal vena cava arises from a hepatic abscess. The commonest result is the subsequent shedding of emboli and the development of a chronic pulmonary disease often terminated by massive pulmonary hemorrhage and bleeding to death through the mouth and nostrils. Others suffer a chronic course with anemia, dyspnea and persistent cough and are euthanatized because of cachexia and prolonged distress.

persistent left cranial v. cava an uncommon anomaly in dogs, often associated with other vascular anomalies such as persistent right aortic arch and tetralogy of Fallot.

posterior v. cava caudal vena cava.

venectasia [ve“nk-ta’zh] phlebectasia.

venectomy [ve-nek’t-me] phlebectomy.

V-4: Ultrasonogram of liver and normal caudal vena cava imaged from the 11th intercostal space using a 3.5-MHz linear transducer. The caudal vena cava has a triangular shape on cross section. 1, abdominal wall; 2, liver; 3, caudal vena cava; Ds, dorsal, Vt, ventral.

From Braun U: Clinical findings and diagnosis of thrombosis of the caudal vena cava in cattle. Vet J 175:118–125, 2008. Elsevier.

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Tags: Saunders Comprehensive Veterinary Dictionary

Jul 18, 2016 | Posted by admin in PHARMACOLOGY, TOXICOLOGY & THERAPEUTICS | Comments Off

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