O

O

O chemical symbol, oxygen; [L.] oculus (eye); [L.] octarius (pint); opening.

o- symbol, ortho-.

Ω the Greek capital letter omega; symbol for ohm.

ω omega, small letter; twenty-fourth letter in the Greek alphabet.

O antigen see O antigen.

O-F test see oxidation-fermentation test.

oak [ōk] tress and shrubs in the genus Quercus. Includes chestnut oak (Q. prinus), English oak, sessile oak (Q. pretraea, Q. robur), European oak (Q. robur), Gambel’s oak (Q. gambelii), jack oak (Q. marilandica), northern red oak (Q. rubra var borealis), post oak (Q. stellata), sand shin oak (Q. havardii), scarlet oak (Q. coccinea), shin oak, shinnery oak (Q. havardii), yellow-barked oak (Q. velutina).

poison o. Toxicodendron diversilobum, T. quercifolium.

silky o. Grevillea robusta.

oat [ōt] member of the plant genus Avena in the family Poaceae.

oats see Avena sativa.

o. grain seed of Avena sativa, and as ‘oats’ the favored grain for the feeding of horses. Too light in energy concentration for the heavy feeding of ruminants.

o. grass Avena pubescens. See also oatgrass.

o. hair calculi large, intestinal trichobezoars composed entirely of oat hairs and capable of causing intestinal obstruction.

o. hay made from cereal oat crop (Avena sativa) it is a popular feed for herbivores but it may have a high nitrate content if it has been well fertilized, and if it gets moldy and overheated, develops a high nitrite content and is poisonous. Must be harvested in the boot stage for adequate nutritional quality. See also nitrite poisoning.

o. hulls a high-fiber, low-protein, low-energy feed.

o. sickness stiffness and restriction of movement in horses soon after a heavy feed of grain; a vague syndrome thought to be due to sensitivity to grain of any sort in particular horses.

o. straw used as bedding and as feed when supplemented with a nitrogen-rich feed such as urea. Like oaten hay may cause nitrite poisoning if moldy.

oat-shaped cell inflammatory cells seen in pneumonic lung, and characterized by elongated or streaming nuclei.

oaten pertaining to or emanating from oats.

oatgrass Arrhenatherum elatius (tall oatgrass), Danthonia (California oatgrass), Trisetum flavescens (golden oatgrass, yellow oatgrass).

ob- word element. [L.] against, in front of, towards.

obcecation [ob“se-ka’shn] incomplete blindness.

obedience training a standardized program of training for dogs calculated to give owners mastery of their dogs at all times. The grades of increasing excellence vary between countries. A popular grading is Companion Dog (CD), Companion Dog Excellent (CDX), Utility Dog (UD) and Utility Dog Excellent (UDX).

Obeliscoides a genus of nematodes in the family Trichostrongylidae.

O. cuniculi found in the stomach of rabbits; in heavy infestations causes gastritis.

Obermayer’s test a test for indican in the urine using a solution of ferric chloride and hydrochloric acid and added chloroform. A blue-violet color develops in a positive test.

obese [o-bēs’] characterized by obesity.

obesity [o-bēs’-te] excessive accumulation of fat in the body; increase in weight beyond that considered desirable with regard to species, age and bone structure, and to a degree greater than that regarded as overweight. A quantitative definition is 15% above optimal weight in dogs and 20% in cats. See also overweight, body condition score.

o. fold pyoderma see fold dermatitis.

obex [o’beks] a small triangular membrane at the caudal end of the roof of the fourth ventricle of the brain.

object–film distance in the taking of a radiograph the distance between the object and the film; the shorter the distance the sharper the image and the less the magnification.

objective [ob-jek’tiv] 1. perceptible by the external senses. 2. the lens or system of lenses of a microscope nearest the object that is being examined.

immersion o. one designed to have its tip and the coverglass over the specimen connected by a liquid instead of air.

obligate [ob’l-gāt] necessary, essential.

o. accumulators see accumulator plants.

obligatory [b-lig’-tor“e] unavoidable; something that is bound to occur.

o. water diuresis polyuria resulting from a decrease or inactivity of antidiuretic hormone on distal tubules and collecting ducts.

oblique [o-blēk’ ] slanting; inclined.

obliquity [o-blik’w-te] the state of being oblique or slanting.

obliteration [ob-lit“r-a’shn] complete removal, by disease, degeneration, surgical procedure, irradiation, etc.

oblongata [ob“long-gah’t] medulla oblongata. See also brain.

Obodhiang virus a rhabdovirus closely related to rabies virus.

O’Brien–Elschnig forceps [o-bri’n] thumb-operated fixation tissue forceps similar to O’Brien forceps except that there is a slide catch that keeps the teeth locked together.

O’Brien forceps [o-bri’n] thumb-operated tissue forceps with blades tipped by long rat-teeth, two on one side, one on the other.

observation 1. something perceived by the senses of the clinician, e.g. pallor of mucosae, as distinct from an interpretation of what is sensed, e.g. anemic. 2. housing of an animal that needs to be quarantined for observation due to the threat of it having contracted various contagious or zoonotic disease processes, e.g. a rabies suspect.

obsessive-compulsive behavior [b-ses’iv-km-pul’siv] normal activities or behavior for the species, but repetitive or constant, even to the point of being damaging to the animal. Includes tail chasing, flank licking and licking.

obstacle test method for behavioral testing of vision by placing objects such as hay bales, colored cones, or furniture in a random pattern in a hall or laneway. The patient is then made to move through the test course in varying light levels; sometimes called maze test.

obstetric, obstetrical [ob-stet’rik] pertaining to or emanating from obstetrics.

o. anesthesia an anesthetic procedure designed especially for patients undergoing cesarean operation or intrauterine manipulation of the fetus. The particular additional responsibility in this kind of anesthesia is the survival of the fetus.

o. assistance assistance to the dam in the expulsion of the fetus varying from simple traction to episiotomy, fetal manipulation in the uterus, fetotomy and cesarean section.

o. chains see obstetric chain.

o. instruments there is a large range including long-handled and finger-grip fetotomy knives; eyehooks, either long-handled or threaded onto obstetric rope; fetotome; obstetric wire; Kuhn’s crutch for repelling or rotating the fetus; obstetric forceps; traction chains and handles; fetal extractor.

o. saw wire saw used in fetotomes. There are two types, Swedish and Gigli wire saws.

obstetrician [ob“st-tr’shn] a veterinarian who specializes in obstetrics and reproductive medicine, in general. See also theriogenologist.

obstetrics [ob-stet’riks] classically in human medicine the branch of medical science dealing with pregnancy, labor and the puerperium. In the veterinary context it is usually limited to the care of the dam and the unborn young during a parturition that cannot be completed, or has slowed to the point that the life of one or both patients is at risk.

obstipation [ob“st-pa’shn] intractable constipation.

obstruction [ob-struk’shn] the act of blocking or clogging; state of being clogged; refers usually to a tubular structure. See intestinal, laryngeal, nasolacrimal duct obstruction, esophageal, oviductal, urethral, ureteral obstruction.

pseudo-o. functional, rather than physical, obstruction of the small intestine can occur with hypomotility and ileus.

ventricular outflow o. see ventricular outflow obstruction.

obstructive having the characteristic of obstruction.

o. colic see equine colic.

o. pulmonary disease see chronic obstructive pulmonary disease.

obstruent [ob’stroo-nt] 1. causing obstruction. 2. any agent or agency that causes obstruction.

obtund [ob-tund’] to render dull or blunt.

obtundation [ob“tn-da’shn] depression as a result of intracranial disease.

obtundent [ob-tun’dnt] 1. aware of environment, but decreased responsiveness to normal stimuli. 2. a soothing or partially anesthetic agent.

obturating pertaining to, having the characteristic of obturation.

obturation the act of closing off, as in intestinal obstruction; in orthodontics filling a root canal.

obturator [ob’t-ra’tr] 1. a disk or plate that closes an opening, e.g. to close a cleft palate temporarily or permanently; the obturator foramen is the large opening in each os coxae that in many species is almost entirely occluded by a sheet of fibrous tissues, the obturator membrane. 2. a sharp or blunt probe used within an endoscopic sheath to assist gaining access to an anatomical regions, for example in the placement of an arthroscope. See also trocar.

o. muscles the muscles that rotate the thigh laterally. See also Table 13.

o. nerve degeneration causes permanent obturator nerve paralysis (below).

o. paralysis commonly follows pressure on the obturator nerve during parturition, especially in cattle; causes inability to adduct the thighs and the cow does the splits. When recumbent the legs are splayed with one on either side of the body.

Occam’s razor a principle named after William of Occam, a 14th century philosopher. The generalization states that, if there are a number of explanations for observed phenomena, the simplest explanation is preferred. Called also scientific parsimony.

occipital [ok-sip’-tl] pertaining to the occiput; located near the occipital bone, such as the occipital lobe.

o. bone the unpaired bone constituting the back and part of the base of the skull. See also Table 10.3.

o. crest see external occipital crest.

o. fracture see basisphenoid fracture.

o. lobe see occipital lobe.

o. somites the most anterior of the embryo’s somites; they are the origin of the occipital cartilages of the skull.

occipitalization [ok-sip“-tl--za’shn] synostosis of the atlas with the occipital bone.

occipitoatlantal of or relating to the occipital bone of the skull and the atlas cervical vertebrae.

occipitoatlantoaxial pertaining to the occiput, the atlas and the axis.

O-1: Obturator paralysis.

From Dyce KM, Sack W, Wensing CJG, Textbook of Veterinary Anatomy, 3rd Edition. Saunders, 2002.

o. malformation see atlanto-occipital malformation of Arab horses.

occipitocervical [ok-sip“-to-sur’v-kl] pertaining to the occiput and neck.

occipitofrontal [ok-sip“-to-fron’tl] pertaining to the occiput and the forehead.

occipitomastoid [ok-sip“-to-mas’toid] pertaining to the occipital bone and mastoid process.

occipitomental [ok-sip“-to-men’tl] pertaining to the occiput and chin.

occipitoparietal [ok-sip“-to-p-ri’-tl] pertaining to the occipital and parietal bones or lobes of the brain.

occipitotemporal [ok-sip“-to-tem’p-rl] pertaining to the occipital and temporal bones or regions.

occipitothalamic [ok-sip“-to-th-lam’ik] pertaining to the occipital lobe and thalamus.

occiput [ok’s-pt] the back of the skull. The external occipital protruberance and the occipital crests; may normally be very prominent in some dogs. Sometimes traumatized with hematoma formation resulting.

occlude [-klōōd’ ] to fit close together; to close tight; to obstruct or close off.

occlusal [-kloo’zl] pertaining to closure; applied to the masticating surfaces of the teeth. The cat does not have any teeth with occlusal surfaces.

occlusio pupillae pupil occlusion; a complete fibrovascular membrane across the pupil.

occlusion [o-kloo’zhn] 1. the act of closure or state of being closed; an obstruction or a closing off. 2. the relation of the teeth of both jaws when in functional contact during activity of the mandible. A system for classification of occlusion in carnivores exists: Class 0 is normal occlusion (called also orthoclusion); Class I is a malocclusion in which the jaws are of normal length, but there are abnormalities in the position of individual teeth; includes anterior and posterior crossbites, base-wide and base-narrow canines, rotated teeth (called also neutroclusion); Class II malocclusion includes those due to a short mandible or long maxilla (called also distoclusion); Class III malocclusion includes those due to a long mandible or short maxilla (called also mesioclusion); Class IV malocclusions have Class II on one side and Class III on the other (called also mesiodistoclusion).

abnormal o. see malocclusion.

coronary o. see coronary occlusion.

functional o. contact of the maxillary and mandibular teeth that provides the highest efficiency in the centric position and during all exclusive movements of the jaw that are essential to mastication without producing trauma.

O-2: (A) Class II malocclusion in a dog. (B) Class III malocclusion in a dog.

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

inflow o. a technique used in cardiac surgery to produce complete circulatory arrest by temporarily interrupting venous return.

traumatic o. any abnormality of occlusion which causes injury to structures within the mouth.

occlusive [-kloo’siv] pertaining to or effecting occlusion.

occult [-kult’] obscure or hidden from view.

o. blood test examination, microscopically or by a chemical test, of a specimen of feces, urine, gastric juice, etc., to determine the presence of blood not otherwise detectable. Feces are tested when intestinal blood loss is suspected but there is no visible evidence of blood in the stools. This is most likely when the bleeding is low grade and into the small intestine. Positive results can be due to swallowed blood, intestinal ulcers or neoplasms, and inflammatory bowel disease. Red meat or fish in the diet can give positive test results.

o. virus the virus or infectious agent cannot be isolated but there is strong circumstantial evidence that it is present.

occupation time parameter for usage of pens in a feedlot.

occurrence in epidemiological terms means frequency of a disease without defining incidence or prevalence.

OCD osteochondrosis dissecans.

ocelli simple eyes of insects.

ocelot (Leopardus pardalis) a member of the family Felidae, native to Central and South America. It is small, golden to silver color with dark metallic spots on the body and stripes on the head and neck; sometimes kept as a pet.

ochratoxicosis [o“kr-tok“s-ko’sis] the nephropathy caused by poisoning by the mycotoxin ochratoxin A. Characterized by degeneration of renal epithelium, polydipsia, polyuria, diarrhea and uremia. Pigs most affected. Resembles Balkan nephropathy in humans.

ochratoxin, ochratoxin A [o’kr-tok“sin] mycotoxin synthesized by Aspergillus ochraceous and some Penicillium fungi with nephrotoxic, immunotoxic, teratogenic and hepatotoxic activities and found in a wide variety of climates and geographical regions as a natural contaminant of poultry and livestock feedstuffs. Causes nephropathy in all species tested with large species differences in potency, pigs being most sensitive. Teratogenicity and immunotoxicity occur only at doses higher than those causing nephrotoxicity. Categorized as a group 2 carcinogen by the WHO.

Ochroconis galloparvum a genus of dematiaceous members of the Fungi Imperfecti.

O. gallopavum a thermophilic dematiaceous hyphomycete known to cause dactylariosis, an encephalitis in chickens and poults. Previously called Dactylaria gallopava and Diplorhinotrichum gallopavum.

O. humicola recovered from cats, a tortoise and fish. Previously classified as Scolecobasidium humicola.

ochrometer [o-krom’-tr] an instrument for measuring capillary blood pressure.

ochronosis [o“kr-no’sis] a yellow, brown or chocolate discoloration of cartilage, tendon sheaths and ligaments but not bone. Caused by deposit of alkapton bodies as the result of a metabolic disorder. Affected parts must be condemned as not suitable for human consumption.

ocular o. brown or gray discoloration of the sclera, sometimes involving also the conjunctivae and eyelids.

Ochsner forceps a strongly built, curved hemostat with rat-tooth tips to the blades.

Ocicat a new breed of cats, derived from crossing a chocolate point Siamese with a hybrid Abyssinian pointed Siamese. It is large with a long nose, large ears and a distinctive spotted coat in many different colors. Named because of its resemblence to an ocelot.

O’Connor program a breeding management system designed to ensure pregnancy in beef cows, based on a 63 day breeding season, having the cows in good body condition, the cows gaining weight during the breeding season, removal of sucking calves, and the use of fertile bulls.

OCT ornithine carbamoyl transferase, a liver specific enzyme.

octa- word element. [Gr., L.] eight.

octachloronaphthalene one of the toxic highly chlorinated naphthalenes.

octadepsipeptides see emodepside.

octan occurring on the eighth day (every 7 days).

¹³C-octanoic acid stable isotope of octanoic acid, a naturally occurring medium chain fatty acid which is rapidly and completely absorbed in the duodenum and oxidized in the liver to CO₂. Used as a measure of gastric emptying.

¹³C-o. acid breath test an indirect measure of gastric emptying.

octatropine anisotropine.

octavalent [ok“t-va’lnt] having a valency of 8.

octopus [ok’t-ps] cephalopod in the order Octopoda; has eight legs and eats crustaceans and shellfish.

blue-ringed o. (Hapalochlaena spp.) small, highly poisonous bane of surf beaches; has blue rings on the tentacles which show up when it is handled. The venom contains tetrodotoxin and causes deaths in humans.

octreotide [ok-tre’o-tīd] a long-acting, synthetic somatostatin analog that inhibits secretion of insulin, growth hormone, glucagon and other hormones; used in the treatment of endocrine disorders of the pituitary and pancreas, including insulinomas.

ocular [ok’u-lr] 1. pertaining to the eye. 2. eyepiece (of a microscope).

o. albinism complete lack of melanin within the typically pigmented ocular structures (iris, ciliary body, retinal pigment epithelium and choroid).

extrinsic o. muscles see extraocular muscles. See also Table 13.1F.

o. filariasis see thelaziasis, onchocercosis.

o. globe see eye.

o. implant drug delivery devices placed in or around the eye to provide constant release of medication to the eye. The devices may be soluble or insoluble.

o. lymphomatosis see Marek’s disease.

o. neurectoderm ectoderm which gives rise to ocular tissues.

o. reflexes a series of subcortical neurological responses involved in normal ocular function; see pupillary light reflex, corneal reflex, consensual pupillary light reflex and palpebral reflex.

o.-skeletal dysplasia see oculoskeletal dysplasia.

o. ultrasound ultrasound examination of the eye is used to detect foreign bodies, intraocular masses, retinal detachment, lens luxation and vitreous pathology (syneresis, asteroid hyalosis, vitreous hemorrhage, etc.) when the usually clear ocular media (cornea, anterior chamber, lens, vitreous) prevent direct examination.

ocul(o)- word element. [L.] eye.

oculocardiac reflex bradycardia or cardiac arrest in the anesthetized animal as a result of manipulating the eye. A potential hazard of ophthalmic surgery.

oculocentesis paracentesis of the eye (aqueocentesis, sub-retinal aspirate, vitreocentesis).

oculocephalic reflex see doll’s eye reflex.

oculocutaneous [ok“u-lo-ku-ta’ne-s] pertaining to or affecting both the eyes and the skin.

o. hypopigmentation affected Angus cattle are brown instead of black and have heterochromia; they are photophobic.

oculofacial [ok“u-lo-fa’shl] pertaining to the eyes and face.

oculogyration [ok“u-lo-ji-ra’shn] the movement of the eye about the anteroposterior axis.

oculomotor [ok“u-lo-mo’tr] pertaining to or affecting eye movements.

o. nerve the third cranial nerve; it contains motor and parasympathetic fibers. Various branches of the oculomotor nerve provide for muscle movement in most of the extraocular and intraocular muscles and resulting in globe movement, constriction of the pupil, accommodation and eyelid opening. See also Table 14.

o. nerve paralysis causes pupillary dilatation and absence of pupillary light reflex if parasympathetic fibers are compromised (internal ophthalmoplegia) and ventrolateral deviation of the globe, defective eye movement and palpebral ptosis if the extraocular motor fibers are involved (external ophthalmoplegia).

oculomotorius the oculomotor nerve.

oculomycosis [ok“u-lo-mi-ko’sis] any fungal disease of the eye.

oculonasal [ok“u-lo-na’sl] pertaining to the eye and the nose.

oculoplastic [ok“u-lo-plas’tik] plastic surgery of the eye, eyelids, ocular muscles, lacrimal apparatus, or orbit.

oculopupillary [ok“u-lo-pu’p-lar-e] pertaining to the pupil of the eye.

oculoskeletal dysplasia [ok“u-lo-skel’-tl dis-pla’zh] a syndrome of disproportionate dwarfism and retinal dysplasia sometimes with retinal detachment and blindness reported in Labrador retrievers and Samoyeds.

O-3: Odd-eyed white cat.

oculovestibulocephalic reflex [ok“u-lo-ves-tib’u-lo-s-fal’ik re’fleks] see doll’s eye reflex.

oculozygomatic [ok“u-lo-zi“go-mat’ik] pertaining to the eye and the zygoma.

oculus [ok’u-ls] pl. oculi [L.] eye.

OD 1. [L.] oculus dexter (right eye). 2. overdose.

odd-eyed cat complete heterochromia in which a cat has one blue eye and the other is yellow, green, or brown.

oddi sphincter see sphincter of Oddi.

oddments in wool marketing includes locks, bellies, crutchings, stained wool.

odds [odz] a method of expressing probability, e.g. at odds of 3 to 2 this can be converted to conventional terminology by using each number as the numerator and the sum of them as the denominator, i.e. 3/5, 2/5 or 60% or 40% or 0.6, 0.4. The odds are quoted as for or against. So that at odds of 3 to 2 the chances for an event happening are 3/5. The odds against it happening are 2/5.

posterior o. probability determined after consideration of the results of a study.

o. ratio the ratio, used particularly in case-control studies, estimates the chances of a particular event occurring in one population in relation to its rate of occurrence in another population.

Odland’s bodies keratinosomes.

Odobenus rosmarus see walrus.

Odocoileostrongylus tenuis see Parelaphostrongylus tenuis.

odontalgia [o-don-tal’j] pain in a tooth; toothache.

odontectomy [o“don-tek’t-me] extraction of a tooth.

odontic [o-don’tik] pertaining to the teeth.

odont(o)- word element. [Gr.] tooth.

odontoameloblastoma [o-don“to-am“-lo-blas-to’m] a tumor containing areas of ameloblastic epithelium and compound or complex odontoma.

odontoblast [o-don’to-blast] one of the connective tissue cells that deposit dentin and form the outer surface of the dental pulp adjacent to the dentin.

odontoblastic emanating from or pertaining to odontoblast.

o. layer the epithelioid layer of odontoblasts in contact with the dentin of teeth.

o. processes see dentinal fibers.

Odontoceti the suborder of toothed whales. Includes sperm whales, porpoises, grampuses, dolphins, beaked whales, bottlenosed whales and narwhals.

odontoclast [o-don’to-klast] an osteoclast associated with absorption of the roots of deciduous teeth.

odontoclastic [o-donto’-klast’-ik] pertaining to odontoclasts. feline o. resorption lesions non-carious defects of enamel, dentin, cementum and alveolar bone, predominantly around the cementoenamel junction but also around the root canal or pulp chamber of molars and premolars, in cats; commonly lead to loss of teeth, particularly in mature age cats. Called also neck or cervical line lesions.

feline o. resorptive lesions non-carious defects of enamel, dentin, cementum and alveolar bone, predominantly around the cementoenamel junction but also around the root canal or pulp chamber of molars and premolars, in cats; commonly leads to loss of teeth, particularly in mature age cats. Called also neck or cervical line lesions or simply tooth resorption.

odontodysplasia cystica congenita [o-don’to-dis-pla’zh sis’ti-k knjen’– t] a disease of calves recorded in Germany and thought to be due to environmental influences; characterized by abortion or stillbirth and congenital fibrous, cystic enlargement of mandibles and maxillae, and absence or deformity of some teeth.

odontogenesis [o-don“to-jen’-sis] the origin and development of the teeth.

o. imperfecta dentinogenesis imperfecta.

odontogenic [o-don“to-jen’ik] 1. forming teeth. 2. arising in tissues that give origin to the teeth.

o. cyst epithelium-lined cysts derived from cell rests or malformed enamel organs. See also dental cyst.

odontogeny odontogenesis.

odontoid [o-don’toid] like a tooth.

o. process see odontoid process.

odontologist [o“don-tol’-jist] dentist.

odontology [o“don-tol’-je] 1. scientific study of the teeth. 2. dentistry.

odontolysis [o-don-tol’-sis] the resorption of dental tissue.

odontoma [o-don-to’m] a non-neoplastic malformation, a hamartoma, consisting of a mixture of enamel, dentin and cementum.

ameloblastic o. contains true neoplastic ameloblastic tissue. See ameloblastic odontoma.

complex o. all the dental tissues are represented but not in an organized form.

composite o. one consisting of both enamel and dentin in an abnormal pattern.

compound o. all the dental tissues are present and organized into denticles, tooth-like structures.

radicular o. one associated with a tooth root, or formed when the root was developing.

temporal o. most commonly in the mastoid process of the petrous temporal bone manifested as a discharging sinus at the base of the ear. Called also dental or dentigerous cyst.

odontopathy [o“don-top’-the] any disease of the teeth.

odontoplasty [o-don’to-plas“te] remodeling of a tooth involving the removal of enamel.

odontoprisis [o-don“to-pri’sis] see bruxism.

odontosis [o“don-to’sis] formation or eruption of the teeth.

odontotomy [o“don-tot’-me] incision of a tooth.

odor [o’dr] a volatile emanation, usually unpleasant, perceived by the olfactory sense of the clinician. See also taint.

boar o. the rank male odor of the male pig, present in the meat of uncastrated male pigs more than 4 months old. Caused by androsterone. See also boar taint.

butyric acid o. odor of rancid butter.

irradiation o. meat sterilized by irradiation may develop a hydrogen sulfide odor.

sexual o. includes boar odor. Buck goat meat has a similar taint but in other ruminants the odor is much weaker. Female odors are not noteworthy with the possible exception of the meat from a sow in estrus at the time of slaughter.

O-4: Small abnormal supernumerary teeth associated with the mandibular molars typical of a compound odontoma.

From DuPont GA, DeBowes JL, Atlas of Dental Radiography in Dogs and Cats. Saunders, 2008.

odorant [o’dr-nt] any substance capable of stimulating the sense of smell.

-odynia word element. [Gr.] pain.

odynometer [o“din-om’-tr] an instrument for measuring pain; see also algometer.

odynophagia [od“-no-fa’j] painful swallowing of food.

oe- for words beginning thus, see also those beginning e-.

Oeciacus vicarius [e-si’-ks] the cliff swallow bug, possibly an overwintering vector for the western equine encephalomyelitis virus.

oedema edema.

Oedemagena a genus of flies similar to Hypoderma spp.

O. tarandi found in the caribou, musk-ox and reindeer. Causes significant damage to the skin and the lesions are conducive to blowfly strike. Called also reindeer warble fly.

Oenanthe [e-nan’the] a genus of the plant family Apiaceae; contain the toxin oenanthotoxin, a toxic alcohol which causes sudden death, convulsions and no lesions; includes O. aquatica (horsebane), O. crocata (hemlock water dropwort), O. fistulosa (water dropwort), O. lachenalii (parsley water dropwort), O. palustris, O. pimpinelloides, O. sarmentosa, O. silaifolia.

oenanthetol one of the poisonous alcohols in the plant Oenanthe crocata.

oenanthetone one of the poisonous alcohols in the plant Oenanthe crocata.

oenanthotoxin one of the poisonous alcohols in the plant Oenanthe crocata. Used loosely also to identify the group of three acetylenic alcohols, oenanthotoxin, oenanthetol, oenanthetone. Causes pupillary dilatation, salivation and convulsions in cattle, pigs and horses. Sheep are not as susceptible.

oesophageal see esophageal.

Oesophagodontus [e-sof“-go-don’ts] a nematode genus in the family Strongylidae.

O. robustus one of the large strongyles of horses. Causes strongylosis.

Oesophagostomum [e-sof“-gos’to-mm] a genus of roundworms in the family Chabertiidae. Found in the large intestine. Cause the important disease esophagostomosis (esophagostomiasis) in sheep. Includes O. aculeatum, syn. O. apiosternum (monkeys); O. asperum, syn. O. indicum (goats, sheep); O. bifurcum (monkeys); O. brevicaudatum (pig); O. columbianum (sheep, goats, camels and wild antelopes); O. dentatum (pig); O. georgianum (pig), O. granatensis (pig), O. hsiungi (pig), O. longicaudatum,. O. quadrispinulatum (pig), O. maplestonei (pig), O. multifoliatum (goat, sheep), O. okapi (okapi); O. quadrispinulatum (pig), O. radiatum (water buffalo, cattle); O. rousseloti (pig); O. staphanostomum (monkeys), O. venulosum (camel, deer, goat, sheep), O. walkeri (eland).

oesophagus [-sof’-gs] see esophagus.

oestrogen see estrogen.

oestrogenism see estrogenism.

Oestromyia leporina a fly similar to Hypoderma spp. Which parasitizes moles and muskrats.

oestrone see estrone.

Oestrus a genus of bot flies in the family Oestridae.

O. ovis a widespread species that deposits its larvae on the nostrils of sheep and goats. Invasion of the nasal cavity causes irritation manifested by sneezing, nose rubbing, noisy breathing and nasal discharge. It may cause ocular myiasis in humans. Called also sheep nasal bot fly.

oestrus estrus.

O-5: Oesophagostomum dentatum, the ‘nodular worm’ of swine, induce formation of large nodules within the wall of the large intestine.

From Hendrix CM, Robinson E, Diagnostic Parasitology for Veterinary Technicians, 4th Edition. Mosby, 2012.

OFA Orthopedic Foundation for Animals; an organization dedicated to recording statistical data on orthopedic diseases, especially hip dysplasia in dogs.

off term used when talking of a horse’s age, e.g. ‘6 off’ for a horse which has just passed 6 years, as opposed to ‘rising 7’ for approaching 7 years.

off-center said of an X-ray beam which is not centered exactly over the part to be examined; the rays will be diverging as they pass it and the image will be distorted.

off feed the animal’s food intake is less than normal.

off-flavor abnormal unappetizing flavor.

off-focus in radiography the radiation composed of X-rays produced by the interaction of electrons with objects, usually metal, other than the tube’s target.

off-label see extra-label.

off-patent drugs see generic (2).

off-shears said of sheep which have been recently shorn.

off-side the off-side of a horse is the horse’s right hand side. The horse is always mounted from the left or near side.

offal 1. nonmeat edible products from animal slaughter. Includes brains, thymus, pancreas, liver, heart, kidney, tripes, sausage casings, chitterlings, crackling rind. 2. by-product of milling, called also weatlings, middlings. A high-protein supplement for herbivores.

specified bovine o. the term used in the UK to denote tissues that can be infected with the agent of bovine spongiform encephalopathy (BSE), namely brain and spinal cord, spinal ganglia, retina, and terminal small intestine. In the USA and some other countries, called ’specified risk materials’.

Office International des Epizooties (OIE) see World Organisation for Animal Health.

office laboratory procedures clinical pathology tests suitable for use in a consulting room or from a country practitioner’s vehicle.

official drugs [o-f-’shl] medicines authorized by pharmacopeias and recognized formularies. Use of drugs other than these could be regarded by a court of law as being experimental.

OFFLU the joint OIE and FAO network of expertise on influenza, established in 2005 to support international efforts to monitor and control infections of avian influenza in poultry and other bird species, and to share biological material and data to support early development of human pandemic vaccines.

offspring progeny generally; includes calf, lamb, kid, pig, foal, chicken, poult, duckling, puppy, kitten, cria. See also Table 16.

ofloxacin [o-flok’s-sin] a second generation fluoroquinolone antibiotic.

Ogmocotyle a genus of intestinal flukes (digenetic trematodes) in the family Notocotylidae.

O. indica a parasite of sheep, goats and cattle, infecting stomach and small and large intestines, but thought to be nonpathogenic.

Ohara’s disease [o-hah’rah] see tularemia.

OHCS hydroxycorticosteroids.

OHE medical record abbreviation for ovariohysterectomy.

ohm (Ω) [ōm] the SI unit of electrical resistance, being that of a resistor in which a current of 1 ampere is produced by a potential difference of 1 volt.

ohmmeter [ōm’me-tr] an instrument that measures electrical resistance in ohms.

Ohm’s law the electric current flowing through a conductor is equal to the voltage divided by the resistance.

-oid suffix meaning resembling.

OIE Office International des Epizooties. See World Organisation for Animal Health.

OIF ovulation induction factor.

oil [oil] 1. an unctuous, combustible substance that is liquid, or easily liquefiable, on warming, and is not miscible with water, but is soluble in ether. Such substances, depending on their origin, are classified as animal, mineral or vegetable oils. 2. a fat that is liquid at room temperature.

automobile o. see crankcase oil (below).

o. of chenopodium extracted from the plant Chenopodium ambrosioides. An old-time anthelmintic.

o.-contamination the coating of spilled crude oil on waterbirds that destroys the waterproofing and insulating properties of their feathers, predisposing them to hypothermia and impairing flight and swimming abilities. It also blocks nares, causes aspiration pneumonia, and has toxic effects on kidneys, reproduction and the gastrointestinal tract.

crankcase o. waste oil from engines; palatable to cattle; calves may drink large amounts if they gain access. Lead poisoning may result, but the introduction of unleaded petroleum has significantly reduced the lead concentration in this material and practically abolished this risk. See also lead¹ poisoning. Called also sump oil.

o. crop crops grown primarily for their oil production, e.g. linseed, safflower, sunflower, rapeseed.

crude petroleum o. crude oil and its several distillates are all relished by cattle and can cause poisoning. The oil as it is extracted from subterranean deposits varies widely in its additional contents. These may be salt or sulfur and cause poisoning by those substances. Oil causes vomiting and death from aspiration pneumonia. Animals do not do well and oil stays in the gut, appearing in the feces for long periods.

diesel and fuel o. see crude oil.

essential o. volatile oils extracted from plant sources by distillation or cold-pressing; many are used in alternative therapies such as aromatherapy. Some, including oils of camphor, citrus, melaleuca, pennyroyal and witnergreen, have significant toxicity for dogs and cats and should not be used.

ethereal o. see essential oil (above).

fixed o. an oil that does not evaporate on warming and occurs as a solid, semisolid or liquid.

o. gland see uropygial glands.

irritant o. occurs in plants; causes gastroenteritis; includes bryonin, croton and castor oils.

mineral o. a mixture of liquid hydrocarbons from petroleum. Mineral oil is available in both light (light liquid petrolatum) and heavy (liquid, or heavy liquid, petrolatum) grades. Light mineral oil is used chiefly as a vehicle for drugs, though it may also be used as a cathartic and to cleanse the skin. Heavy mineral oil is used as a cathartic, solvent and oleaginous vehicle. Excessive intake over a long period results in hypovitaminosis A.

o. pollution aquatic birds are worst affected because of pasting together of feathers, poisoning because of contamination of food source, blocking of nares and eyes and starvation because of unpalatability of food supply.

o. products includes kerosene (or kerosine, or paraffin), gasoline (or petrol), diesoline and additives to lubricating oils, e.g. highly chlorinated naphthalenes; any of them may cause poisoning.

o. spill accidental or negligent discharge of industrial oil on a body of water; effect is that the oil floats and pollutes the shore and covers aquatic birds and mammals with fatal results in most cases; salvage depends on capture of affected birds and animals and removing the oil.

sump o. see crankcase oil (above).

sweet o. olive oil.

sweet birch o. see methyl salicylate.

turpentine o. see turpentine oil.

volatile o. an oil that evaporates readily; such oils occur in aromatic plants, to which they give odor and other characteristics. See also essential oil (above).

o. of Wintergreen see methyl salicylate.

yew o. an irritant oil in Taxus spp., but not the principal toxin in that plant—taxine is.

oilseed the seeds of the linseed plant, rapeseed or canola, peanut, safflower (Carthamus tinctorius); biproduct oils from seeds include corn, grapeseed, olive, sesame, sunflower.

ointment [oint’mnt] a semisolid preparation for external application to the body. Official ointments consist of medicinal substances incorporated in suitable vehicles (bases).

okapi (Okapia johnstoni) a member of the giraffe family Giraffidae, but with short legs and neck. It has a similar head, face and lips to the giraffe, is about 5 ft tall at the withers and has horizontal stripes on its hindquarters and limbs, resembling those of a zebra.

Okavirus a genus in the family Roniviridae, order Nidovirales; members infect crustaceans, mostly prawns. The type species is gill-associated virus.

Okazaki fragments [o-kah-zah’ke] DNA sequences, 100 to 200 nucleotides long, synthesized on the lagging strand of DNA in DNA replication. The fragments are subsequently ligated together to form a continuous strand. They are produced because of the need for DNA polymerase to always synthesize in a 5’ to 3’ direction.

Okie a system of grading of feeder calves purchased for feedlots and based on percentage of beef versus dairy blood in the breeding. The bulk of these cattle are yearling, baldy-faced, Hereford cross steers. The name is a contraction of Oklahoma.

OL [L.] oculus laevus (left eye).

-ol word termination indicating an alcohol or a phenol.

olamine [ol’-mēn] USAN contraction for ethanolamine.

olaquindox a growth stimulant used as a feed additive for pigs.

Olax benthamiana Australian plant in the family Olacaceae; causes cyanide poisoning.

old dog encephalitis see old dog encephalitis.

Old English mastiff see Mastiff.

Old English sheepdog a large, compact dog distinguished by its profuse, shagg coat in gray, grizzle, blue or blue merle, with or without white markings, that covers the body, including the face, and obscures most of the body features. The tail is either naturally short or docked to a very short length. Called also the English bobtail. The breed is predisposed to congenital deafness, myelopoietic disorders, inherited cataracts and demodectic mange.

old man’s beard Clematis vitalba.

old tuberculin see tuberculin.

Old World the Eastern Hemisphere; that part of the world (generally Europe, Asia, Africa) which was known before the discovery of America.

Oldenburgh 1. polled, German mutton and wool sheep. Called also Oldenburg whitehead, German whitehead. 2. a German breed of carriage horses, later refined through the introduction of Thoroughbred blood. Now an all purpose saddle horse, prized for dressage. They are usually black, brown or gray.

-ole suffix meaning a small.

oleaginous [o“le-aj’-ns] oily; greasy.

oleander [o“le-an’dr] Nerium oleander, but also used in the common name of other plants.

yellow o. Cascabela thevetia (Thevetia peruviana).

oleandomycin a macrolide antibiotic extracted from cultures of Streptomyces antibioticus, similar to, but less active and more toxic than erythromycin. Used as the phosphate salt.

oleandroside a digitoxin-like glycoside, one of the toxic substances in Nerium oleander.

oleate [o’le-āt] 1. a salt of oleic acid. 2. a solution of a substance in oleic acid.

olecranarthritis [o-lek“rn-ahr-thri’tis] inflammation of the elbow joint.

olecranarthropathy [o-lek“rn-ahr-throp’ah-the] disease of the elbow joint.

olecranoid [o-lek’r-noid] resembling the olecranon.

olecranon [o-lek’r-non] the bony projection of the ulna at the elbow.

olefin [o’l-fin] see alkene.

oleic acid [o-le’ik] a long-chain, 18-carbon, monounsaturated fatty acid found in animal and vegetable fats, particularly olive oil; the double bond is located at carbons 9,10; precursor of n-9 or omega 9 fatty acids.

olein [o’le-in] 1. pertaining to oleic acid. 2. a principal constituent of nondrying fats and oils. Called also triolein, glyceryl trioleate. Animal fat containing a high proportion of olein has a greasy character.

ole(o)- word element. [L.] oil.

oleo oil the oily fraction of rendered animal fat.

oleoresin [o“le-o-rez’in] 1. a compound of a resin and a volatile oil, such as exudes from pines, etc. 2. a compound extracted from a drug by percolation with a volatile solvent, such as acetone, alcohol, or ether, and evaporation of the solvent.

oleostearin a firm fraction of rendered animal fat, used in margarine manufacture.

oleotherapy [o“le-o-ther’-pe] treatment with oil, particularly by injection.

oleothorax [o“le-o-tho’raks] intrapleural injection of oil to compress and inactivate the lung.

oleovitamin [o“le-o-vi’t-min] a preparation of fat-soluble vitamins in fish liver or edible vegetable oil.

oleum [o’le-m] pl. olea [L.] oil.

olfact [ol’fakt] a unit of odor, the minimal perceptible odor, being the minimal concentration of a substance in solution which can be perceived by a large number of normal individual animals, expressed in terms of grams per liter.

olfact- [ol’fakt] prefix meaning sense of smell.

olfaction [ol-fak’shn] 1. the act of smelling. 2. the sense of smell.

olfactology [ol“fak-tol’-je] the science of the sense of smell.

olfactometer [ol“fak-tom’-tre] an instrument for testing the sense of smell.

olfactory [ol-fak’t-re] pertaining to the sense of smell.

o. bulb see olfactory bulb.

o. glands in the mucosa of the nasal olfactory region; branched tubuloalveolar glands secreting serous fluid; cleanse the mucosal surface, dissolve odor-producing substances.

o. hair modified cilia projecting from olfactory cells in the mucosa of the nasal olfactory area.

o. mucosa specialized olfactory cells in a region of nasal mucosa covering ethmoturbinates, turbinates and nasal septum.

o. nerve the first cranial nerve made up of about 20 bundles and concerned with the sense of smell. The cell bodies are situated in the olfactory mucous membrane of the nose. Nerve fibers lead caudad through openings in the cribriform plate of the ethmoid bone and connect with the cells of the olfactory bulb. From there the fibers pass inward to the cerebrum. See also Table 14.

o. neuroblastoma rare neoplasm, commonest in pups and kittens, characterized by local invasion of surrounding bone.

o. pit primordia of the nasal cavities commencing as pits in the olfactory placodes of the embryo. The pits deepen and finally open into the oral cavity as the choanae; the external orifices become the nostrils. Called also nasal pit.

o. system includes the olfactory part of the nasal mucosa, the olfactory nerves and the olfactory bulbs of the cerebrum.

o. tract a band of white nerve fibers visible on the ventral surface of the brain running caudally from the olfactory bulbs.

o. tractotomy surgical removal or transection of the olfactory tracts to produce an anosmia may be performed in cats as a means of controlling spraying and inappropriate urination.

olifantvel [Af.] the thickened, wrinkled, alopecic skin caused by Besnoitia besnoiti in cattle.

oligemia [ol“-je’me-] deficiency in volume of the blood. Estimation of the degree of oligemia, the severity of dehydration, is a vital assessment in many diseases of animals. See packed cell volume, dehydration.

olig(o)- word element. [Gr.] few, little, scanty.

oligochromasia [ol“-go-kro-ma’se-] deficiency of hemoglobin in the blood.

oligochymia [ol“-go-kī’me-] deficiency of chyme.

oligocythemia [ol“-go-si-the’me-] deficiency of the cellular elements of the blood.

oligodactyly [ol“-go-dak’t-le] congenital absence of one or more digits. Called also hypodactyly.

oligodendrocyte [ol“-go-den’dro-sīt] non-neuronal (glial) cell of the central nervous system that produces myelin in the developing brain and maintains it thereafter.

oligodendroglia [ol“-go-dn-drog’le-] oligodendrocyte.

oligodendroglioma [ol“-go-den“dro-gli-o’m] brain or spinal cord tumor thought to arise from oligodendrocytes.

oligodipsia [ol“-go-dip’se-] abnormally diminished thirst.

oligodontia [ol“-go-don’sh] congenital absence of some of the teeth. Considered a serious fault of conformation in some dog breeds.

oligodynamic [ol“-go-di-nam’ik] active in a small quantity; refers to the antimicrobial effect of very dilute solutions of metals such as silver and copper.

oligogalactia [ol“-go-g-lak’she-] deficient secretion of milk.

oligohemia oligemia.

oligohydramnios [ol“-go-hi-dram’ne-os] deficiency in the amount of amniotic fluid.

oligohydruria [ol“-go-hi-droo’re-] hypersthenuria.

oligomeganephronia [ol“-go-meg’-n-fro’ne-] congenital renal hypoplasia in which there is a reduction in the total number of nephrons, and hypertrophy of the nephrons.

oligomer [ol’-go-mr] a short polymer.

oligomucous cell [ol’-go-mu’ks] a cell which develops into a goblet cell in the intestinal epithelium.

oligomycin [ol’-go-mi’sin] antibiotic inhibitor of oxidative phosphorylation, acting at the O-sensitive subunit of F₀F₁-ATPase.

oligonucleotide [ol“-go-noo’kle-o-tīd] a polymer made up of a few to a hundred or more nucleotides. Can be made synthetically to a specified sequence.

o. ligation assay a technique for detecting a single nucleotide polymorphism (SNP) allele in a gene.

oligopeptides [ol“-go-pep’tīd] small peptides containing mixtures of amino acids.

oligophosphaturia [ol“-go-fos“f-tu’re-] deficiency of phosphates in the urine.

oligoplasmia [ol“-go-plaz’me-] deficiency of blood plasma.

oligopnea [ol“-gop-ne’] hypoventilation. Usually refers to reduced rate; apnea is complete cessation.

oligoptyalism [ol“-go-ti’-liz-m] diminished secretion of saliva.

oligosaccharide [ol“-go-sak’-rīd] a carbohydrate which yields only a small number, usually 3 to 10, of monosaccharides on hydrolysis.

oligospermia [ol“-go-spur’me-] low volume of ejaculate; not to confuse with oligozoospermia, which is low number of spermatozoa in the ejaculate.

oligotrophia, oligotrophy a state of poor (insufficient) nutrition.

oligozoospermia [ol“-go-zo“o-spur’me-] low number of spermatozoa in the ejaculate.

oliguria [ol“-gu’re-] reduced daily output of urine, which may be physiologic or pathologic. This has veterinary significance if the net intake is normal or if water is available ad lib; then it is a sign of renal insufficiency.

olingo (Bassaricyon gabbii) small, arboreal, nocturnal member of the Procyonidae; native to rainforests of Central and South America.

olivary [ol’-var“e] shaped like an olive.

o. body called also olivary nucleus; see olive (2).

o. nucleus see olive (2).

olive 1. the tree Olea europaea and its fruit. 2. olivary body; a rounded elevation lateral to the upper part of each pyramid of the medulla oblongata.

o. oil an emollient lubricant and mild laxative.

olivifugal [ol“-vif’u-gl] moving or conducting away from the olive.

olivipetal [ol“-vip’-tl] moving or conducting toward the olive.

olivocerebellar tract [ol“-vo-ser“-bel’r] nerve fibers passing from olive to contralateral cerebellum.

olivopontocerebellar [ol“-vo-pon“to-ser“-bel’r] pertaining to the olive, the middle peduncles and the cerebellar cortex.

Ollier’s disease [o-le-a’] multiple enchondromatosis, dyschrondroplasia.

Ollulanus [ol“u-lan’us] a genus of trichostrongyloid nematodes in the family Ollulanidae.

O. tricuspis found in the stomach of cats, foxes, wild cats and pigs. Causes chronic gastritis and emaciation in pigs and vomiting and wasting in cats.

olsalazine [ol-sal’-zēn] 5-amino-salicylate; used in the treatment of ulcerative colitis.

Olsen-Hegar needle holder a combination instrument constructed as a needle holder except that the half of each blade nearest to the pivot is shaped like a regular scissor blade. Used for driving the needle, then cutting the suture without changing instruments.

-olus suffix meaning a small.

-oma word element. [Gr.] tumor, neoplasm.

OMAGOD oral mucosal and gum obscure disease. An acronym for idiopathic oral ulceration present in up to 5% of normal sheep. A ‘tongue-in-cheek’ name coined during the 2001 outbreak of foot-and-mouth disease in the United Kingdom. Not to be confused with the instant messaging slang, OMG (oh my God), even though in the circumstances in which the term evolved that may have been applicable.

omarthritis [o“mahr-thri’tis] inflammation of the shoulder joint.

omasal [o-ma’sl] pertaining to or emanating from the omasum.

O-6: Olson-Hegar needle holder–scissors combination.

From Sonsthagen TF, Veterinary Instruments and Equipment: A Pocket Guide, 2nd Edition. Mosby, 2011.

< div class='tao-gold-member'>

Only gold members can continue reading. Log In or Register to continue

Related

Stay updated, free articles. Join our Telegram channel

Tags: Saunders Comprehensive Veterinary Dictionary

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

Full access? Get Clinical Tree

Get Clinical Tree app for offline access

Get Clinical Tree app for offline access