Z

Z symbol for zetta.

Z zeta, capital letter; sixth letter in the Greek alphabet; symbol for atomic number.

ζ zeta, small letter; sixth letter in the Greek alphabet.

Z band, Z line a band of electrodense, noncontractile protein which runs across themuscle fiber and towhich themyofibrils are attached.

Z-inactivation occurs in birds because dosage compensation for Z-linked genes does not occur in birds.

Z-linkage genes with loci on the Z chromosome.

Z-linked sexing use of alleles at Z-linked loci to determine sex of chicks at an early age. See fast feathering.

Z-myoplasty a technique for surgical correction of quadriceps muscle contracture.

Z-plasty repair of a skin defect by the transposition of two triangular flaps of adjacent skin to provide relief of skin tension, or for relaxation of scar contractures. Called also zigzagplasty.

Z-tenectomy a technique for tendon shortening.

Z-tenotomy a technique for tendon lengthening.

Zackel sheep a group of horned breeds of sheep widely dispersed through Europe and Asia. Used for carpetwool, meat and milk. Mostlywhite, some are brown, black or pied. Males have long spiral horns, females may be polled. Most breeds have long, thin tails.

Zalaphotrema a genus of digenetic trematodes which includes Z. hepaticum found in the liver of the sea lion.

Zaleya galericulata member of the Aizoaceae plant family; suspected to cause soluble oxalate poisoning, causing nephrosis, urolithiasis. Called also hogweed.

zamang see Samanea saman.

Zamia American genus of cycads in the family Zamiaceae; causes incoordination, due to degeneration of the spinal cord, and hepatic necrosis. The toxin is identified as a cycad glycoside. Includes Z. integrifolia (Z. floridana, Z. media), Z. portoricensis, Z. pujilla, Z. pumila (Z. debilis, Z. latifoliata, Z. silvicola, Z. umbrosa). Called also coonties, Florida arrowroots, marangvey, derriengue, guayiga. See also zamia staggers.

zamia see cycad.

z. fern Bowenia spectabilis.

z. staggers irreversible posterior paresis and paralysis in cattle in Australia; caused by an unidentified toxin of cycad leaves or seeds; degenerative lesions present in spinal cord white matter, including the proprioceptive pathways. See also derriengue.

tree z. Cycas armstrongii, C. media.

zang-fu organs see yin organs and yang organs.

Zanha africana African tree in the family Sapindaceae; contains a toxic saponin; plant causes diarrhea and dysentery in browsing ruminants. Called also Dialiopsis.

Zantedeschia aethiopica member of the plant family Araceae; toxin is calcium oxalate raphide crystals; causes stomatitis, salivation. Called also arum lily, calla lily, varkoor.

Zea mays a grass in plant family Poaceae. A staple part of human and animal diet in many countries as corn or maize meal. The standing green crop, up to 10 ft high, makes excellent ensilage and green chop. May be infested with poisonous fungi in the field or as stored grain. May cause nitrate–nitrite poisoning. Called also corn, maize.

zearalanol [z-ral′-nol] see zeranol.

zearalenone [z-ral′-nōn] an estrogenic substance produced during the fermentation of stored grain by the fungus Fusarium graminearum. The effects of the toxin are enlargement of the pudenda, infertility and death of the newborn. See also zeranol.

zeboid a class of cattle intermediate between zebu and humpless British breed cattle, e.g. Chinese yellow, Sanga, Santa Gertrudis, Droughtmaster. Called also taurindicus.

zebra (Equus spp.) horse- or ass-like animals with a distinctive black and white striped coat, large ears, tufted tail and stiff mane. There are three species: plains or common zebra (E. quagga), mountain zebra (E. zebra), and Grevy’s zebra (E. grevyi), and some recognized subspecies.

z. marks faint striping in coats of horses, usually on the legs, also the neck and withers.

zebrafish see Danio rerio.

zebronkey a cross between zebra and donkey.

zebu a group of breeds of humped cattle, including Indian, East and West African, and most breeds of South-East Asian cattle. Origin of the Chinese Yellow, Sanga and Brahman. Includes Africander, Sahiwal, Sindhi and many others.

zein [ze′in] the principal protein in corn. Has low nutritive value, being deficient in lysine and tryptophan.

Zeis glands [tsīs] see glands of Zeis.

Zenith an Australian medium-woolled (21.5 to 23 microns), dualpurpose, polled sheep, produced by crossing sheep of Merino and Lincoln breeds.

Zenker’s necrosis, degeneration [tseng′ker] see Zenker’s necrosis.

zeony progeny of a zebra and a pony.

Zephyranthes see Cooperia pedunculata.

Zepp operation a modification of the lateral ear resection in dogs in which a cartilaginous flap is turned downward and sutured in place as a ‘drainboard’ at the bottom of the opening created. It serves to reduce the possibility of stricture of the horizontal canal and minimize growth of haircoat at the opening which might impede aeration and drainage.

zepto- (z) [L.] seven; a prefix used in the metric system of measurement to indicate one-thousand-million-million-millionth (10⁻²¹) of the unit designated by the root with which it is combined.

zeranol [zer′-nol] a synthetic zearalenone (6′-reduced zearalenone) marketed as Ralgro used as a growth promotant in cattle. Called also zearalanol.

zernike condenser special condenser used in phase contrast microscope.

zero [ze′ro] the point on a thermometer scale from which the graduations begin. The zero of the Celsius (centigrade) scale is the ice point; on the Fahrenheit scale it is 32° below the ice point.

absolute z. the lowest possible temperature, designated 0 on the kelvin or Rankine scale, the equivalent of −273.15°C or −459.67°F.

zero-order reactions generally pertaining to enzyme reactions where the rate of product formation is independent of substrate concentration.

zeta [za′t] seventh letter in the Greek alphabet, Z or ζ.

zeta potential see zeta potential.

zetamethrin a beta-cypermethrin. Used in ear tags for control of ectoparasites on cattle.

zetta- (Z) [Gr.] seven; a prefix used in the metric system of measurement to designate an amount 10²¹ (a thousand-million-millionmillion or a sextillion) times the unit specified by the root to which it is joined, as zettabyte.

zeugopodium [zoo″go-po′de-m] the segment of the limb corresponding to either the forearm or the leg.

zho, zo see dzo.

zidovudine [zi-do′vu-dēn] a thymidine analog with antiviral activity used in the treatment of AIDS in humans; has been used for feline immunodeficiency virus and feline leukemia virus infections in cats. Called also azidothymidine (AZT).

Ziehl-Neelsen stain [tsēl′ nāl′sen] a carbol-fuchsin stain most used for the detection of Mycobacterium spp.

Zieria an Australian genus of shrubs and trees of the Rutaceae family.

Z. arborescens causes atypical interstitial pneumonia in cattle. There is a grunting dyspnea and a nasal discharge. Called also stinkwood.

Z. laevigata, Z. smithii suspected of causing cyanide poisoning.

Z-1 Ziehl-Neelsen stain. Acid-fast organisms mycobacterial organisms (arrowheads) are strongly stained bright red.

From Raskin RE, Meyer D, Canine and Feline Cytology, 2nd Edition. Saunders, 2010.

Z-2 Abomasal necrosis in a ewe that drank from a zinc sulfate footbath solution.

Zieve’s syndrome [zēv] a human disease characterized by hemolytic anemia related to a low lipid content of erythrocyte cell membranes; some clinical similarity to hemoglobinuria which occurs in event horses after prolonged exercise.

zigadenine, zigadine, zygadenine plant toxin found in Zigadenus spp.

Zigadenus North American and African genus of the Liliaceae family. There are many species, some of them toxic some not. The toxins in the plants are steroid alkaloids of the veratrum group. Poisoning is characterized by salivation, vomiting, tachycardia, weakness, prostration and dyspnea. Death may occur within a few hours or not for a number of days. The list of toxic plants includes Z. chlorantus, Z. densus, Z. elegans, Z. fremontii, Z. glaberimus, Z. glaucus, Z. intermedius, Z. leimanthoides, Z. nuttallii, Z. paniculatus, Z. venenosus (Z. gramineus). Called also Toxicoscordion, Zygadenus, death camus.

zigzagplasty see Z-plasty.

Zimmerman’s aluminum wire suture [ts′mer-mahn] see Zimmerman’s aluminum wire suture.

zinc (Zn) [zingk] a chemical element, atomic number 30, atomic weight 65.37. See Table 4. Zinc is a trace element that is a component of several enzymes, including DNA and RNA polymerases, and carbonic anhydrase. Zinc salts are used in skin lotions, eye washes, the treatment and prevention of footrot of sheep and facial eczema of sheep and cattle.

z. acetate a salt used as an astringent and styptic.

z. cadmium sulfide used in the preparation of fluoroscopic screens; is fluorescent and emits yellow-green light when excited by X-rays.

z. carbonate a mild astringent; used mainly as calamine.

z. chromate an industrial compound used in cold galvanizing of metal. Accidental access causes diarrhea and fatal enteritis.

z. finger motif sequence of approximately 30 amino acids, forming a helix-turn-helix, believed to form a structure that includes tetrahedrally coordinated zinc (II) ions. Found in many eukaryotic, prokaryotic and viral DNA-binding proteins.

z. finger protein DNA-binding proteins that contain zinc-finger motifs.

z. gelatin a mixture of zinc oxide, gelatin, glycerin and purified water; used topically as a protectant.

z. gluconate a source of supplementary zinc.

hereditary z. deficiency lethal trait A46; Adema disease; see inherited parakeratosis.

z. methionine a nutritional animal feed supplement that is used to prevent and/or control zinc deficiency in animal species, particularly cattle and camelids.

z. nutritional deficiency causes parakeratosis in pigs, a chronic, afebrile, noninflammatory disease of the epidermis characterized by crusty proliferation and cracking of the skin. Dogs fed diets with high concentrations of calcium or cereals may have poor absorption of zinc and develop signs of deficiency, primarily in the skin. See also zinc-responsive dermatosis.

z. ointment a preparation of zinc oxide and mineral oil in white ointment; used topically as an astringent and protectant.

z. oversupplementation causes hemolytic anemia, anorexia and vomiting.

z. oxide a compound used as a topical astringent and protectant. Inhalation of fumes causes interstitial emphysema and atelectasis.

z. phosphate used as a phosphate-bonded cement in restorative dentistry.

z. phosphide used commercially to control insect and rodent populations. Phosphine gas is liberated when the parent compound comes into contact with acidic moist environments. Clinical signs in poisoned animals are due to multisystemic effects (lung, liver, heart, kidney) of the parent and metabolite, although initial gastrointestinal signs predominate.

z. poisoning can be chronic and causes stiffness and lameness with particular involvement of the shoulder joint in which there is a degenerative arthritis (might be associated with a copper deficiency). In acute poisoning there is gastroenteritis with vomiting, abdominal pain, diarrhea and a Heinz body hemolytic anemia.

z.-responsive dermatoses see parakeratosis, zinc-responsive dermatosis.

z. stearate a compound of zinc with stearic and palmitic acids; used as a water-repellent protective powder in dermatoses.

z. sulfate a compound used as an ophthalmic astringent, in skin lotions (see white lotion), for sheep footrot, and the treatment of facial eczema. It is the common form of zinc for oral supplementation and treatment of zinc-responsive diseases.

z. sulfate flotation test used to demonstrate nematode eggs, protozoan cysts and larvae in feces and bronchial secretions.

z. sulfate turbidity test 1. serum globulins are precipitated by zinc sulfate. The test is used for the semiquantitative assessment of the immunological status of foals and calves when there is a question of whether they have suckled to receive immunoglubulins. 2. an outdated liver function test.

z. undecylenate a compound used topically in 20% ointment as an antifungal agent. See also undecylenic acid.

zineb an antifungal preparation used extensively agriculturally but without any apparent toxicity hazard.

zipper structure leucine [zip′r] see leucine zipper.

zipper worm [zip′r] Spirometra erinacei.

zirconium (Zr) [zir-ko′ne-m] a chemical element, atomic number 40, atomic weight 91.22. See Table 4.

z. chlorhydrate an astringent.

Zn chemical symbol, zinc.

zoacanthosis a dermatitis caused by penetration into the skin, of bristles, hairs, etc., of lower animals.

zolazepam [zo′la-z-pam] a benzodiazepine tranquilizer most commonly used in a fixed-ratio combination with tiletamine.

Zoletil a fixed-ratio combination of the tranquilizer, zolazepam, with the dissociative anesthetic, tiletamine; used for injection anesthesia in dogs, cats, wild and zoo animals. It produces dosedependent sedation to general anesthesia.

Zollinger-Ellison syndrome [zol′in-jr el′-sn] a triad comprising intractable, sometimes fulminating, upper gastrointestinal ulceration, extreme gastric hyperacidity, and nonbeta cell, gastrinsecreting, islet cell tumors (gastrinomas) of the pancreas. Clinical signs in affected dogs include vomiting, often with blood, anemia, diarrhea, weight loss, and sometimes signs of peritonitis.

zona [zo′n] pl. zonae [L.] zone.

z. alba the white line in the horse’s hoof.

z. fasciculata the thick middle layer of the adrenal gland.

z. glomerulosa the outermost layer of the adrenal cortex. Called also zona multiformis.

z. multiformis see zona glomerulosa (above).

z. pellucida 1. the transparent, noncellular, secreted layer surrounding an ovum. 2. area pellucida.

z. radiata a thickenbed cell membrane of the oocyte of certain animals such as some amphibia which exhibits conspicuous radial striations. Called also zona striata.

z. reaction caused by the penetration of the zona pellucida by the spermatozoa.

z. reticularis the innermost layer of the adrenal cortex.

z. striata see zona radiata (above).

zona-free hamster ovum penetration ability assay a test of sperm function; the zona pellucida penetration assay is preferred.

zona pellucida penetration assay a test of sperm function preferred to the simpler zona-free hamster ovum penetration assay.

zone [zōn] an encircling region or area; by extension, any area with specific characteristics or boundary. See also zona.

autonomous innervation z. areas of innervation supplied by a single nerve, as for example the patch of skin on the medial side of the horse fore pastern which is supplied solely by the median nerve; used to assess the integrity of individual nerves.

axonic z. the all-or-none conducting zone of the three functionally significant zones of the neuron; includes axis cylinder and part of the arborizing axonal terminal.

ciliary z. the outermost of the three regions of the iris. See also pupillary zone (below) and iris collarette.

comfort z. an environmental temperature between 55° and 70°F (13° and 21°C) with a humidity of 30 to 55%.

cut back z. the part of any metaphysis of a long bone where the cortex is reduced to a narrower diameter than the adjacent growth plate; the process involves remodeling of primary and secondary trabeculae within cortical bone. It is a conspicuous feature on radiographs where the cortical margin appears roughened and, similarly, on bones prepared by maceration where this cut-back zone has a characteriistic porous appearance.

epileptogenic z. an area, stimulation of which may provoke an epileptic seizure.

equivalence z. a ratio of antigen and antibody which results in precipitation in which there is no unbound antibody or antigen.

focal z. in ultrasound, the area of the transducer where the sound beam is most sharply focused and where the area under examination will give the best image.

Fraunhofer z. in ultrasonography, the area of the sound beam beyond the focal zone where the beam diverges and resolution decreases.

Fresnel z. in ultrasonography, the area of the sound beam between the transducer and the focal zone in which complex diffraction patterns occur.

grenz z. a zone of relatively normal collagen demarcating the boundary between normal epidermis and a dermal lesion such as a granuloma or a neoplasm.

z. of inhibition the area without bacterial growth surrounding an antimicrobial-impregnated disk in an antimicrobial sensitivity test.

marginal z. the rim of tissue surrounding lymph follicles in the spleen which contains many lymphocytes and macrophages.

provisional calcification z. in developing bone longitudinal tubes of mineralized matrix which surround hypertrophic chondrocytes.

pupillary z. the innermost of the three regions of the iris, immediately outside the pupil. See also ciliary zone and iris collarette.

thermoneutral z. the ambient temperature at which mammals and birds can maintain their body temperature without increasing thermogenesis or evaporative heat loss.

transitional z. equitorial region of the crystalline lens in which epithelial fibers are transformed into lens fibers; the lens bow.

white z. horn of the hoof separating the wall horn from the sole horn; more common name is white line.

zonifugal [zo-nif′-gl] passing outward from a zone or region.

zonipetal [zo-nip′-tl] passing toward a zone or region.

zonisamide [zo-nis′-mīd“] a sulfonamide anticonvulsant.

zonula [zo′nu-l] pl. zonulae [L.] zonule.

z. adherens common component of junctional complexes between epithelial cells; forms an effective barrier between the lumen and connective tissue. Called also tight junction.

z. ciliaris the suspensory apparatus of the lens consisting of zonular fibers that extend from the ciliary processes to the lens capsule.

z. occludens see tight junction.

zonule [zo′nūl] a small zone.

ciliary z. a series of fine collagenous fibers connecting the ciliary process tips with the equatorial lens capsule, holding the lens in place. Called also lens zonule, zonule of Zinn.

zonulitis [zo″nu-li′tis] inflammation reflected on the ciliary zonule.

zonulolysis, zonulysis [zo″nu-lol′-sis, zo″nu-li′sis] dissolution of the ciliary zonule by use of enzymes, to permit surgical removal of the lens.

zonulotomy [zon″u-lot′o-me] incision of the ciliary zonule.

zoo a collection of wild animals kept in close or open confinement, usually for public viewing. There are strict licensing provisions for such places to ensure that the welfare of the animals is taken care of, and the safety of the public, and that the possibility of an exotic disease being introduced with additions of animal specimens from foreign countries is avoided. See also game farm.

zo(o)- word element. [Gr.] animal.

zoodermic [zo″o-dur′mik] performed with the skin of another species of animal, especially in reference to skin grafts.

zoogenous [zo-oj′-ns] 1. acquired from animals. 2. viviparous.

zoogeny [zo-oj′-ne] the development and evolution of animals.

zoogeography [zo″o-je-og′r-fe] defining the location and numbers of animal populations, and their variability with time.

zoogony [zo-og′-ne] the production of living young from within the body.

zoografting [zo′o-graft″ing] the grafting of animal tissue.

zooid [zo′oid] 1. animal-like. 2. an animal-like object or form. 3. an individual in a united colony of animals.

zoology [zo-ol′-je] the biology of animals.

zoom control in ultrasonography, a means of magnifying part of the image.

Zoomastigophora [zo″o-mas″t-gof′-r] a group of protozoa (zooflagellates), including all of the flagellates that parasitize higher animals.

zoonosis [zo-on′-sis] disease or infection that is naturally transmissible from vertebrate animals to humans. It can be bacterial, viral, or parasitic, or may involve unconventional agents. Zoonoses are a public health concern, but also create obstacles to international trade in animal products.

direct z. one transmitted by contact or via an inanimate vehicle and which requires only one reservoir vertebrate (passing directly from animal to humans without the involvement of a vector or intermediate host) to maintain the cycle of infection, e.g. rabies. See also cyclozoonosis, metazoonosis, saprozoonosis.

emerging z. newly recognized or newly evolved, or showing an increase in incidence or expansion in geographical, host or vector range.

reverse z. disease transmitted from humans to animals, such as tuberculosis.

zooparasite [zo″o-par′-sīt] any parasitic animal organism or species.

zoopathology [zo″o-p-thol′-je] the science of the diseases of animals.

zoophagous [zo-of′-gs] carnivorous.

zoophilic [zo″o-fil′ik] preferring animals to humans; said of certain fungi.

zoophobia [zo″o-fo′be-] abnormal fear of animals.

zoospore [zo′o-spor] a motile mitospore; a motile, flagellated, asexual spore, as produced by certain algae and fungi, and Dermatophilus congolensis.

zoospores see ruminal zoospores.

zootechny [zo″o-tek′ne] animal management as distinct from animal husbandry which includes the science, economics and biometry of the care of farm animals.

zootoxicosis disease caused by a zootoxin.

zootoxin [zo′o-tok″sin] a toxic substance of animal origin, e.g. venom of snakes, spiders and scorpions.

Zr chemical symbol, zirconium.

zwitterion [tsvit′er-i″on] an ion that has both positive and negative regions of charge. Called also dipolar ion.

zwoegersiekte [Dutch] see maedi.

zygacine one of the toxic alkaloids in Zigadenus.

Zygadenus see Zigadenus.

zygadine one of the toxic alkaloids in Zigadenus.

zygal [zi′gl] shaped like a yoke.

zygapophysis [zi″g-pof′-sis] the articular process of a vertebra. See also facet joints.

zygion [zij’e-on] the most lateral point on the zygomatic arch.

zyg(o)– word element. [Gr.] yoked, joined, a junction.

zygodactylous having two toes directed forwards and two backwards as in some birds, e.g. parrots.

zygodactyly [zi″go-dak′t-le] union of digits by soft tissues (skin), without bony fusion of the phalanges involved.

zygoma [zi-go′m] 1. the zygomatic process of the temporal bone. 2. zygomatic arch. 3. a term sometimes applied to the zygomatic bone.

zygomatic [zi″go-mat′ik] pertaining to zygomatic bone.

z. arch the arch formed by the processes of the zygomatic and temporal bones.

z. bone the bone forming the hard part of the cheek and the lower, lateral portion of the rim of the orbit. See also Table 10.

z. gland a salivary gland, formerly known as the orbital or upper molar gland, best developed in carnivores; located above the zygomatic arch and below the eye. Enlargement or mucocele of the gland causes exophthalmos.

z. mucocoele accumulation of salivary secretions from the zygomatic gland. It appears as a protruding mass under the conjunctiva of the lower eyelid.

z. process a projection from the frontal or temporal bone, or from the maxilla, by which they articulate with the zygomatic bone.

zygomaticofacial [zi″go-mat“-ko-fa′shl] pertaining to the zygoma and face.

zygomaticotemporal [zi″go-mat“-ko-tem′pr-l] pertaining to the zygoma and temporal bone.

zygomorphism the anatomical principle of bilaterality of antimeres (right and left halves of the body).

Zygomycetes [zi″go-mi-se’tēz] see Phycomycetes.

zygomycetes [zi″go-mi-se′tēz] members of the taxonomic class of fungi which includes two orders, Mucorales and Entomophthorales.

zygomycosis [zi″go-mi-ko′sis] rare infection by fungi in the class, Zygomycetes, causes granulomatous lesions in many species, most often in the gastrointestinal tract. A rare example is Conidiobolus incongruus infection causing cutaneous granulomata and invasion of the lungs as in nasal zygomycosis in sheep. Immune suppression is believed to be a predisposing factor. See also mucormycosis, entomophthoromycosis. Most infections previously called phycomycosis were believed to have been caused by zygomycetes.

zygomycotes members of the Zygomycota phylum of fungi. Includes Mucor, Rhizopus spp.

zygon [zi′gon] the stem connecting the two branches of a zygal fissure.

Zygophyllum plant genus in the family Zygophyllaceae; can cause nitrate–nitrite poisoning; suspected of causing mortality in sheep and cattle. Called also Roepera, twin leaf. Includes Z. ammophilum, Z. apiculatum.

zygosity [zi-gos′-te] the condition relating to conjugation, or to the zygote, as (1) the state of a cell or individual in regard to the alleles determining a specific character, whether identical (homozygosity) or different (heterozygosity); or (2) in the case of twins, whether developing from one zygote (monozygosity) or two (dizygosity).

zygospore [zi′go-spor] a thick-walled sexual spore produced by fungi in the class Zygomycetes.

zygote [zi’gōt] the cell resulting from union of a male and female gamete; the fertilized ovum. More precisely, the cell after synapsis at the completion of fertilization until first cleavage.

zygotene [zi′go-tēn] the synaptic stage of the first meiotic prophase in which the two leptotene chromosomes undergo pairing by the formation of synaptonemal complexes to form a bivalent.

zymase enzyme found in yeasts that catalyzes the fermentation of sugar to alcohol and CO₂.

zymic pertaining to enzymes or fermentation.

zym(o)- word element. [Gr.] enzyme, fermentation.

zymodemes populations of parasites with identical isoenzymes.

zymogen [zi′mo-jn] an inactive precursor that is converted into an active enzyme, usually by cleavage of a small polypeptde by action of an acid or another enzyme or by other means; a proenzyme.

z. cells the secretory cells that secrete the zymogens.

z. granules contained in the cytoplasm of the secretory cells in the relevant gland. Contain the zymogen.

Zymonema farciminosum see Histoplasma farciminosum.