M

M macerate; maximal; symbol, mega; member; meter; minim; [L.] mil or mille (thousand); misce (mix); mistura (mixture); symbol, molar (solution)—the expressions M/10, M/100, etc., denote the strength of a solution in comparison with the molar, as tenth molar, hundredth molar, etc.; muscle; myopia.

M99 see etorphine.

m symbol, meter; symbol milli-.

m. minim.

μ mu, the twelfth letter of the Greek alphabet; symbol for micro-; micron (μm).

m- symbol, meta-.

M cells special epithelial cells associated with Peyer’s patches and lymphoid follicles that actively take up particulate matter from the intestinal contents. They are probably the portal of entry for bacteria and viruses.

M component a homogeneous immunoglobulin produced by a single clone of cells in a monoclonal gammopathy. May consist of either whole immunoglobulin molecules or their subunits, e.g. light chains or heavy chains. Called also paraprotein, myeloma protein or M protein.

M-CSF macrophage colony-stimulating factor.

M line a histological structure in myofibrils in skeletal muscle. The line runs transversely to the length of the myofibrils and corresponds to the segment occupied by myosin myofilaments.

M-mode motion mode. See M-mode ultrasonography.

M phase see cell cycle.

M-plasty a technique for suturing a fusiform incision.

M protein myeloma protein; membrane protein.

M substance a dense zone in each myofilament of a muscle fiber and contributing to the M band which runs across the fiber.

mA milliampere.

MA test microscopic agglutination test.

MAb monoclonal antibody.

MAC 1. in anesthetics, minimum alveolar concentration; a measure of potency. 2. in immunology, membrane attack complex.

Macaca [m-kah′k] genus of Old World monkeys in the subfamily Cercopithecinae; includes the macaques.

Macadamia Australian genus of trees in the family Proteaceae; grown commercially for their fruits (macadamia, Australian bush or bopple nut). The leaves and seeds contain cyanogenetic glycosides and are a potential cause of cyanide poisoning. Dogs eating the seed kernels (raw or roasted) develop a transient profound muscle weakness, sometimes with joint pain, caused by an unidentified toxin (not cyanide). Includes M. integrifolia, M. ternifolia, M. tetraphylla, M. whelanii.

macadamia nut toxicity ingestion of one nut or less per pound body weight by dogs can cause weakness, tremors, and ataxia, particularly in the hindlegs, within hours.

MacAllan clamps aluminum clamps used as templates for the cropping of the ears of various breeds of dogs.

macaque [m-kahk′] members of the genus Macaca, of the family Cercopithecoidae, the Old World monkeys. They are generally medium to large-sized, heavily built, and their tails range in length from long to absent. Many species have been important in biomedical research. Includes stump-tailed macaque (M. arctoides); long-tailed or crab-eating macaque (M. fascicularis); rhesus macaque (M. mulatta), see rhesus monkey; pig-tailed macaque (M. nemestrina); crested black macaque (M. nigra); bonnet macaque or bonnet monkey (M. radiata); liontailed macaque (M. silensus); Barbary macaque or Barbary ape (M. sylvana).

McArdle disease [mk-ahr′dl] glycogenosis type V

Macavirus (sigla from malignant catarrhal fever) a genus in the subfamily Gammaherpesvirinae that contains the species Alcelaphine herpesvirus 1, Alcelaphine herpesvirus 2, Hippotragine herpesvirus 1 and Ovine herpesvirus 2, Bovine herpesvirus 6, Caprine herpesvirus 2, Suid herpesvirus 3, Suid herpesvirus 4 and Suid herpesvirus 5.

macaw one of the tropical parrots of the family Psittacidae. Macaws are very colorful, have long tails and bare cheek patches. They are big birds (up to 3 feet long) and are members of the Ara genus, e.g. Ara macao, the scarlet macaw.

m. wasting disease see proventricular dilatation disease.

McBurney incision [mk-bur′ne] see grid incision.

McDonald operation [mk-don′ld] a purse-string retention technique for correction of cervical incompetence in breeding mares.

Macdonaldius a genus of filaroid worms found in the blood vessels of colubrid and viperine snakes. In aberrant host snakes they cause cutaneous ulceration.

McDowall reflex a reflex inwhich section of the vagi in cats subjected to severe hemorrhage causes a decrease in blood pressure.

macerate [mas′r-āt] to soften by wetting or soaking.

maceration [mas″r-a′shn] the softening of a solid by soaking. In histology, the softening of a tissue by soaking, especially in acids, until the connective tissue fibers are dissolved so that the tissue components can be teased apart. In obstetrics, the degenerative changes with discoloration and softening of tissues, and eventual disintegration, of a fetus retained in the uterus after its death. In herbal medicine, certain herbs may require cold water to make produce infusions or decoctions if the active ingredient is susceptible to inactivation by heat.

McFadyean’s reaction a special staining reaction, demonstrating a pink capsule around a blue cell, after staining with methylene blue, which is used as a presumptive diagnosis for anthrax in a blood smear.

McFarland turbidity standard stock solutions of barium sulfate with consistent turbidity used to compare suspensions of bacteria in the disk diffusion method of antimicrobial sensitivity tests.

Mach effect an optical illusion in radiography. Wherever there is a boundary between two objects of different luminosity the retina enchances the image. It leads to the misdiagnosis of fractures in the metacarpal and metatarsal bones. Called also edge effect or enhancement, Mach band.

Machaeranthera ramosa North American plant in the family Asteraceae and a selenium accumulator capable of causing selenosis in grazing livestock.

macho male alpaca.

macies [L.] wasting.

Mackenzie brush technique [m-ken′ze] a method of collecting samples from the haircoat, particularly of cats, for diagnosis of dermatophytosis. A sterile toothbrush is used to brush the hair thoroughly and is then pressed onto a plate or slant of Sabouraud’s agar and incubated.

Mackenzie River disease [m-ken′ze] Australian name for poisoning by Terminalia oblongata.

mackerel see tabby.

Maclura pomifera a North American plant in the family Moraceae; contains an unidentified toxin causing diarrhea in sheep. Called also osage orange, bow wood.

McMaster technique a rapid, simple, quantitative technique for counting parasite eggs in ruminant feces, based on flotation in a concentrated salt solution (specific gravity of 1.1–1.3) in a counting chamber.

McNemar’s chi-square test see chi-square test.

Macracanthorhynchus [mak″r-kan″tho-ring′ks] a genus of large acanthocephalans in the family Oligacanthorhynchidae.

M. catalinum found in the small intestine of dogs, wolves, badgers and foxes.

M. hirudinaceus found in the small intestine of domestic and wild pigs, where they cause granulomatous lesions in the intestinal wall, sometimes perforation and peritonitis.

M-1: Macracanthorhynchus ingens proboscis.

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

M. ingens found in the small intestine of wild mammals including skunk, mink, raccoon and mole.

macrencephalia [mak-ren″s-fa′le-] hypertrophy of the brain.

macr(o)- word element. [Gr.] large, long.

macroamylase [mak″ro-am′-lās] a complex in which normal serum amylase is bound to a variety of specific binding proteins, forming a complex too large for renal excretion. It is not correlated with any specific disease state; however, in hyperamylasemia or pancreatitis, it can result in urinary amylase concentrations not rising concomitantly with serum concentrations.

macroamylasemia [mak″ro-am″l--se′me-] the presence of macroamylase in the blood.

macroblast [mak’ro-blast] an abnormally large, nucleated erythrocyte; a large young normoblast with megaloblastic features.

macroblepharia [mak″ro-bl-far′e-] abnormal largeness of the eyelid.

macrocardius [mak″ro-kahr′de-s] a fetus with an extremely large heart.

macrocarpa Cupressus macrocarpa.

macrocephalous [mak″ro-sef′-ls] having an abnormally large head.

macrocephaly [mak″ro-sef′-le] abnormal enlargement of the cranium.

macrochromosomes [mak″ro-kro′mo-sōmz] a pair of normal chromosomes.

macroclimate the climate as described by standard meteorological information. Paints a broad picture of the weather as perceived by animals and humans, but has little relevance to pasture plants and pathogens.

macrocolon [mak′ro-ko″ln] see megacolon.

macroconidium [mak″ro-ko-nid′e-m] pl. macroconidia; a large conidium produced by some fungi such as Microsporum spp.

macrocrania [mak″ro-kra′ne-] abnormal increase in size of the skull in relation to the face.

macrocyclic lactones [mak″ro-sik′lik] potent nematicidal and insecticidal compounds derived from Streptomyces spp. See also avermectins, milbemycins.

macrocyte [mak′ro-sīt] an abnormally large erythrocyte.

macrocythemia [mak″ro-si-the′me-] the presence of macrocytes in the blood. See macrocytosis.

macrocytic [mak″ro-sit′ik] manifested by or pertaining to the presence of macrocytes.

macrocytosis [mak″ro-si-to′sis] macrocythemia; the presence of macrocytes in the blood. Observed in miniature poodles with a hereditary bone marrow dyscrasia and in greyhounds.

Macrodactylus subspinosus the rose chafer beetle. The population of these beetles can be very high in some years and ingestion of large numbers of them can cause poisoning in birds. Signs include drowsiness, weakness and some deaths. Called also Cetonia aurata.

M-2: Macrocytes (long arrows) and acanthocytes (small arrow) in canine blood film.

From Hendrix CM, Sirois M, Laboratory Procedures for Veterinary Technicians, 5th Edition. Mosby, 2007.

macrodactyly [mak″ro-dak′t-le] abnormal largeness of the digits.

macrodontia [mak″ro-don′sh] one or more abnormally large teeth.

macroelement [mak″ro-el′-ment] any of the macronutrients that are chemical elements, including calcium, phosphorus, magnesium, potassium, sodium and chloride.

macrogamete [mak″ro-gam′ēt] the larger, less active female gamete in anisogamy, which is fertilized by the smaller male gamete (microgamete).

macrogametocyte [mak″ro-g-me′to-sīt] 1. a cell that produces macrogametes. 2. the female gametocyte of ampicomplexan protozoa that matures into a macrogamete.

macroglia [mak-rog′le-] neuroglial cells of ectodermal origin, i.e. the astrocytes and oligodendrocytes considered together.

macroglobulin [mak″ro-glob′u-lin] immunoglobulin M, an antibody protein (globulin) of molecular weight in the range of 1 000 000.

α₂-m. a glycoprotein that inhibits proteolytic enzymes. Increased concentrations are seen in diabetes mellitus and diseases of the liver and kidney.

macroglobulinemia [mak″ro-glob″u-l-ne′me-] increased levels of immunoglobulin M in the blood.

Waldenström’s m. a monoclonal gammopathy in which there are increased levels of IgM as a result of leukemia affecting IgM-producing B lymphocytes.

macroglossia [mak″ro-glos′e-] excessive size of the tongue.

macrognathia [mak″ro-na′the-] abnormal overgrowth of the jaw.

macrogols [mak′ro-gols] a polyethylene glycol used in the manufacure of drugs as solvents.

macrogyria [mak″ro-ji′re-] moderate reduction in the number of sulci of the cerebrum, sometimes with increase in the brain substance, resulting in excessive size of the gyri.

macrohabitat the immediate, large-scale environment, as can be seen with the naked eye; flora, fauna, topography, climate in the broad sense, as an animal would experience it.

macrolide [mak′ro-līd] as in antibiotic; any antibiotic with molecules having many-membered lactone rings, e.g. erythromycin, spiramycin, tylosin.

macromastia [mak″ro-mas′te-] excessive size of the mammary glands.

macromelanosomes [mak″ro-mel′-no-sōm″] large pigment granules; seen in color dilution alopecia.

macromelia [mak″ro-me′le-] enlargement of one or more limbs.

macromelus [mak-rom′-ls] a fetus with abnormally large or long limbs.

macromere [mak′ro-mēr] one of the larger cells (blastomeres) formed in unequal cleavage of the fertilized ovum (at the vegetal pole).

macrometeorology measurement of the macroclimate.

macromineral [mak″ro-min′r-l] the major minerals in animal nutrition (as distinct from trace minerals). Includes calcium, phosphorus, sodium, chlorine, potassium, magnesium, sulfur.

macromolecule [mak″ro-mol′-kūl] a very large molecule having a polymeric chain structure, as in proteins, polysaccharides, nucleic acids, etc.

macromonocyte [mak″ro-mon′o-sīt] a giant monocyte.

macromyeloblast [mak″ro-mi′-lo-blast] a large myeloblast.

macronormoblast [mak″ro-nor′mo-blast] a very large nucleated erythrocyte; macroblast.

macronucleus [mak″ro-noo′kle-s] the larger nucleus when there are two in the cell.

macronutrient [mak″ro-noo′tre-ent] an essential nutrient that has a large minimal daily requirement (greater than 100 mg for a ruminant); calcium, phosphorus, magnesium, potassium, sodium and chloride are macronutrients.

macronychia [mak″ro-nik′e-] abnormally enlarged claws or hooves.

macropalpebral fissure [mak″ro-pal′p-brl fish′r] an abnormally large eyelid aperture that allows greater exposure of cornea, conjunctiva and sclera. Commonly seen in the brachycephalic dog breeds. Causes abnormal distribution of the tear film and lagophthalmos and predisposes to proptosis and exposure keratitis.

macropenis [mak″ro-pe′nis] megalopenis.

macrophage [mak′ro-fāj] any of the large, mononuclear, highly phagocytic cells derived from bone marrow cells, promonocytes, the progeny of which, the monocytes, enter the bloodstream, where they stay for a few days before entering the tissues and developing into macrophages. They are components of the monocyte-macrophage system. Macrophages are usually immobile but become actively mobile when stimulated by inflammation, immune cytokines and microbial products. They are an important class of antigen presenting cells (APCs). See also immunity.

M-3: A macrophage showing erythrophagocytosis.

From Cowell RL, et al Diagnostic Cytology and Hematology of the Dog and Cat, 3rd Edition. Mosby, 2007.

activated m. under the influence of cytokines, particularly ginterferon and interleukin 4, released by antigen-stimulated Th1 lymphocytes, resting macrophages are activated whereby they become larger, more motile, stickier, express more MHCII proteins on their surface, contain more lysosomes and lysosomal enzymes, and secrete a variety of substances including interleukin 1, tumor necrosis factors; they have increased phagocytic activity and increased killing via reactive oxygen intermediates, collagenases and lysosomal enzymes. Called also angry macrophage.

m. activating factor (MAF) a lymphokine that activates macrophages, for example interferon.

alveolar m’s rounded, granular, mononuclear phagocytes within the alveoli of the lungs that ingest inhaled particulate matter.

angry m. see activated macrophage (above).

armed m’s those capable of inducing cytotoxicity as a consequence of antibodies bound via Fc receptors on their surfaces.

m. chemotactic factor (MCF) a lymphokine that attracts macrophages.

m. colony-stimulating factor see colony-stimulating factors.

m. inhibition factor (MIF) a lymphokine that inhibits macrophage migration, causing them to accumulate at the site of antigen.

specific m. arming factor (SMAF) a term for an antigen specific factor produced by sensitized T lymphocytes capable of binding to macrophages, which subsequently exhibit specific cytotoxicity when encountering specific antigen bearing target cells. No such factor has been specifically identified.

macrophthalmia [mak″rof-thal′me-] abnormal enlargement of the eye.

macropinosomes [mak″ro-pin′o-sōms] large droplets filled with fluid formed when excess tissue fluid is engulfed by cells as part of a clean-up of tissue spaces.

macropod [mak″ro-pod] members of the marsupial family Macropodidae.

macropodia [mak″ro-po′de-] excessive size of the feet.

macropolycyte [mak″ro-pol′e-sīt] a hypersegmented polymorphonuclear leukocyte of greater than normal size.

macroprosopia [mak″ro-pro-so′pe-] excessive size of the face.

Macropus a genus in the family of marsupials, Macropododae. Includes kangaroos, wallaroos and some wallaby.

macroreticulocyte large reticulocytes released prematurely from bone marrow; they have a reduced life span.

macrorhabdosis infection by Macrorhabdus ornithogaster; see megabacteriosis.

Macrorhabdus ornithogaster an ascomycetous yeast that causes megabacteriosis in budgerigars. Called also avian gastric yeast.

macroscopic [mak″ro-skop′ik] of large size; visible to the unaided eye.

m. anatomy see gross anatomy.

macroscopy [m-kros′k-pe] examination with the unaided eye.

macrosigmoid [mak″ro-sig′moid] excessive size of the sigmoid colon.

macrosmatic [mak″roz-mat′ik] pertaining to a good sense of smell, e. g. macrosmatic animals such as dogs.

macrosomatia, macrosomia [mak″ro-so-ma′she-, mak″ro-so′me-] great bodily size.

macrotia [mak-ro′sh] abnormal enlargement of the pinna of the ear.

Macrozamia [mak″ro-zam′e-] one of the endemic Australian genera of the cycads in the family Zamiaceae; contain cycad glycosides (e.g. macrozamin) and cause liver necrosis, gastroenteritis and zamia staggers. Species associated with poisoning include M. communis, M. diplomera, M. heteromera, M. lucida, M. miquelii, M. moorei, M. mountperriensis, M. pauli-guilielmi, M. riedlei.; others are suspected. Called also burrawang, zamia.

macrozamin [mak″ro-zam′in] a glycoside of methylazoxymethanol (MAM) in Macrozamia spp. and other cycads.

macula [mak′u-l] pl. maculae [L.] 1. a stain, spot, or thickening; 2. an area distinguishable by color or otherwise from its surroundings. Often used alone to refer to the macula retinae. 3. a moderate size corneal opacity that can be seen without special optical aids; presenting as a gray spot intermediate between a nebula and a leukoma. 4. macula lutea.

m. acusticae terminations of the vestibulocochlear nerve in the utricle and saccule.

m. adherens see desmosome.

m. atrophica a white atrophic patch on the skin.

m. corneae see macula (4) (above).

m. cribrosa a perforated spot or area; one of three perforated areas (inferior, medial and superior) in the wall of the vestibule of the ear through which branches of the vestibulocochlear nerve pass to the saccule, utricle and semicircular canals.

m. densa a zone of heavily nucleated cells in the distal renal tubule.

m. folliculi the point on the surface of a vesicular ovarian follicle where rupture occurs; follicular stigma.

m. germinativa germinal area; the part of the conceptus where the embryo is formed.

inner ear m. sensory receptor areas in the walls of the utriculus and sacculus which monitor the position of the head relative to gravity; see also macula sacculi (below), macula utriculi (below).

m. lutea retinae see macula retinae (below).

m. retinae an irregular yellowish depression on the retina, lateral to and slightly below the optic disk. Seen only in primates. Called also macula lutea.

m. sacculi a thickening on the wall of the saccule where the epithelium contains hair cells that receive and transmit vestibular impulses.

m. utriculi a thickening in the wall of the utricle where the epithelium contains hair cells that are stimulated by linear acceleration and deceleration and by gravity.

nebula 1. a small corneal opacity. See also macula and leukoma. 2. an oily preparation for use in an atomizer.

maculate [mak′u-lāt] spotted or blotched.

macule [mak′ūl] a discolored spot on the skin that is not raised above the surface.

maculocerebral [mak″u-lo-ser′-brl] pertaining to the macula lutea and the brain.

maculopapular [mak″u-lo-pap′u-lr] both macular and papular.

mad apple Datura stramonium.

mad cow disease see bovine spongiform encephalopathy (BSE).

mad itch see Aujeszky’s disease.

mad mushroom see Psilocybe.

madarosis [mad″-ro′sis] loss of eyelashes or eyebrows.

madeira vine see Anredera cordifolia.

madness see mania.

Madura foot [m-doo′r] see maduromycosis.

maduramicin, maduramycin a polyether ionophore used in poultry feed as a coccidiostat.

Madurella [mad″u-rel′] a genus of fungi associated with the lesions of maduromycosis in humans.

maduromycetoma [m-doo′r] maduromycotic mycetoma.

maduromycosis [m-doo′r-mi-ko′sis ] a chronic disease due to various fungi or actinomycetes, affecting various body tissues, particularly the feet; called also mycetoma. The most common form in humans affects the foot (Madura foot) and is characterized by sinus formation, necrosis and swelling. The disease is recorded in the horse, in which there are nasal granulomas and similar lesions in the skin. The fungi Helminthosporium spp., Allescheria spp. and Curvularia spp. are present in the lesions. See also mycetoma.

maduromycotic [m-doo′r-mi-kot-ik] pertaining to or emanating from maduromycosis.

m. mycetoma see mycetoma.

maedi a chronic pneumonia of sheep caused by a lentivirus, which also causes visna when it invades the brain of sheep. In maedi the characteristic features are a prolonged incubation period of more than 2 years, a progressive pneumonia which lasts for about 6 months, initially with dyspnea and respiratory distress at exercise but terminally also at rest, and at the inevitable death, an abnormally high density and heaviness of the lungs. Some sheep show chronic wasting and/or have indurative mastitis. A disease notifiable to the OIE (see Table 22). Called also maedi–visna, Graaff–Reinet disease, la bouhite, ovine progressive pneumonia and lymphoid interstitial pneumonia.

maedi–visna see maedi.

Maesa lanceolata an African plant of the family Myrsinaceae that causes diarrhea, polyuria, emaciation and death in cattle. The principal necropsy lesion is nephrosis; the toxin has not been identified. Called also ol odoa.

MAF macrophage activating factor.

mafenide [maf′n-īd] a sulfonamide that is not inhibited by the presence of pus and necrotic tissue; used mostly for local application to infected wounds, especially burns. Called also homosulfanilamide, sulfamylon.

MAFF [formerly] Ministry of Agriculture, Fisheries and Food, in the UK. See DEFRA.

MEG magnetoencephalography.

maggot [mag′ot] the soft-bodied larva of an insect, especially one living in decaying flesh or tissue debris. See also myiasis.

cattle m. see Hypoderma.

m. debridement therapy (MDT) method for the treatment of intractable, infected and necrotic wounds. Sterile larvae of Lucilia sericata are applied to infected wounds where they debride the wound bed of necrotic tissue and exert antibacterial effects.

rat-tailed m. larva of Eristalis spp., a hover fly of no veterinary importance other than in confusing an identification. Called also filth fly. The maggots are found in areas with high concentrations of organic matter, e.g. stable drains.

wool m. see cutaneous myiasis.

magic mushroom see Psilocybe.

Magill circuit [mgil′] see Magill circuit.

magma [mag′m] 1. a suspension of finely divided material in a small amount of water. 2. a thin, paste-like substance composed of organic material.

Magner war bridle a type of restraint used on horses, it is a rope with a loop around the lower jaw, then passed over the head and back through the jaw loop.

magnesemia [mag″n-se′me-] hypermagnesemia.

magnesia [mag-ne′zh] magnesium oxide; aperient and antacid.

magnesium (Mg) [mag-ne′ze-m] a chemical element, atomic number 12, atomic weight 24.312. See Table 4. Its salts are essential in nutrition, being required for the activity of many enzymes, especially those concerned with oxidative phosphorylation. It is found in the intra- and extracellular fluids and is excreted in urine and feces.

m. ammonium phosphate (MAP) a common constituent of urinary calculi. See urolithiasis.

blood m. concentration of magnesium in the blood. See hypermagnesemia, hypomagnesemia.

m. carbonate, m. hydroxide, m. oxide, m. phosphate, m. trisilicate compounds used as antacids.

m. chloride used as a source of magnesium in the treatment of hypomagnesemia in cattle, and as a chemical defibrillator in cardiopulmonary resuscitation.

m. citrate a mild cathartic.

endogenous m. magnesium contributed to the feces by the intestinal secretions.

m. gluconate a magnesium replenisher.

m. nutritional deficiency is most important in the part that it plays in lactation tetany in ruminants. It also causes deformities of the limbs and nervous signs of tremor and convulsions in pigs. See also lactation tetany (1).

M-4: Nail and wire covering a reticular magnet recovered at postmortem of a cow.

m. 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.

m. salicylate the magnesium salt of salicylic acid used as an analgesic and a non-steroidal anti-inflammatory drug.

m. silicate talcum powder; capable of causing starch granulomatous peritonitis if introduced into the peritoneal cavity, so it has been superseded by other compounds for use on surgeon’s gloves.

m. sulfate Epsom salts; used as an electrolyte replenisher, cathartic and local anti-inflammatory. Used in the treatment of hypomagnesemia in cattle.

m. sulfate–chloral hydrate mixture see chloral hydrate and magnesium sulfate.

magnet [mag′nt] an object having polarity and capable of attracting iron.

oral dose m. see reticular magnet.

reticular m. a magnet placed in the reticulum to attract and isolate sharp metal and help to prevent traumatic reticuloperitonitis in ruminants.

magnetic field strength measured in tesla (T); MRI machines range from 0.2–5 T compared to the earth’s magnetic field which is ∼1/20 000 T.

magnetic field therapy [mag-net′ik] a modality of alternative medicine using magnetic lines of force to stimulate healing, particularly musculoskeletal injuries. It may be used in combination with other modalities of treatment, most commonly acupuncture. Pulsed magnetic field therapy is produced by passing an electric current through a coil of wire. The frequencies commonly produced, 1–60 Hz, pass through the body without causing any thermal effect in tissues.

magnetic resonance imaging (MRI) [mag-net′ik] the patient is placed in a magnetic field and radiofrequency signals are transmitted and received by surrounding coils. A computer processes the information and constructs cross-sectional images which provide detailed information on soft tissues. Functional MRI (fMRI) detects local changes in blood oxygenation that indicate neural activation. See also proton density weighted scans, T₁, T₂.

magnetism [mag′n-tiz-m] magnetic attraction or repulsion.

magnetoencephalography (MEG) [mag•ne•to•en•ceph•a•lo•graph-e] a non-invasive imaging technique that directly measures magnetic fields emitted by neuronal activity in the brain.

magnetropism [mag-net′ro-piz-m] a growth response in a nonmotile organism under the influence of a magnet.

magnification [mag″n-f-ka′shn] 1. apparent increase in size, as under the microscope. 2. the process of making something appear larger, as by use of lenses. 3. the ratio of apparent (image) size to real size. 4. radiologicalmagnification; a factor of object to film distance.

magnum [mag′nm] the highly coiled, second zone of the hen’s left oviduct. About 30 cm long. The albumen-secreting zone. The egg takes about 3 hours to pass through this part.

Mahaim fibers [mah-ă′] short, direct connections from the AV node (or the bundle of His or bundle branches) to muscle fibers in the interventricular septum.

M. fiber conduction a type of accessory AV conduction with abnormal beats originating below the region of normal delay in the AV-conducting system; causes an arrhythmia.

ma huang [mah hwahng′] in traditional Chinese medicine, the name for Ephedra sinica. Called also Chinese ephedra.

maiden 1. a female, e.g. ewe, gilt, heifer, bitch, mare, of breeding age but not yet mated. 2. a racehorse that has not yet won a race on a recognized track.

Main Drain virus [mă] one of the California serotype bunyaviruses isolated in California from a horse with encephalitis.

Maine-Anjou red, red-and-white, or red-roan dual-purpose cattle originating in northern France.

Maine coon cat a breed of cats originating from shipboard cats that landed in the American state of Maine in the 19th century. Now recognized as a distinct breed, it is a very large, muscular, long-haired cat in a variety of colors, although originally tabby.

maintenance requirement [mān′t-nans] in terms of animal nutrition, the amount and quality of the diet required to maintain an adult animal without providing additional nutriment for production, reproduction or weight gain.

m. r. for energy see energy requirements.

m. r. interval the interval between doses of a medication arranged so as to maintain an appropriate blood concentration of the drug.

Maireana brevifolia Australian plant genus in the family Chenopodiaceae; suspected of acute oxalate poisoning; includes M. brevifolia, M. sedifolia. Called also bluebush.

maize [māz] usually referred to as corn (3) in the USA or as maize in other countries. Called also Zea mays.

Majocchi’s granuloma [mah-zhok′e] a form of dermatophytosis with a granulomatous, pyogranulomatous or suppurative reaction containing fungal grains or hyphae. Called also nodular granulomatous perifolliculitis.

major histocompatibility complex [ma′jr] see major histocompatibility complex.

mal [mahl] [Fr.] illness. disease.

m. de caderas see Trypanosoma equinum.

m. de mer seasickness.

m. de playa South American name for Lantana poisoning.

m. des mains sales see hydatid disease.

m. do eucalipto disease caused by poisoning with the fungus Ramaria spp.

m. du coit see dourine.

grand m. a generalized convulsive seizure attended by loss of consciousness. See also generalized tonic-clonic seizure.

petit m. momentary loss of consciousness without convulsive movements. See also partial seizure.

m. seco [Span.] South American name for grass sickness, dysautonomia.

mala [ma′l] the cheek or cheek bone.

malabsorption [mal″b-sorp′shn] impaired intestinal absorption of nutrients.

fat m. see steatorrhea.

m. syndrome a group of disorders marked by subnormal intestinal absorption of dietary constituents, and thus excessive loss of nutrients in the stool, with chronic diarrhea and weight loss; it may be due to a digestive defect, a mucosal abnormality, or lymphatic obstruction. A common disease in dogs and a major part of some of the enteric diseases of food animals. It is the pathogenesis of the diarrheas of trichostrongylosis of sheep and cattle, of the viral diarrheas of pigs and the undifferentiated chronic diarrheas of horses.

malaccol an insecticidal substance present in the roots of Derris spp. plants.

malachite green a green dye used to stain bacteria and as an antibacterial and antifungal. Used, with great caution, as a treatment of cutaneous mycosis in aquarium fish.

m. g. test used to determine the completeness of bleedout in an abattoir carcass. Also used to detect the presence of the meat preservative, sodium metabisulfite.

malacia abnormal softening or softness of a part or tissue; also used as a word termination, as in osteomalacia, encephalomalacia, myelomalacia.

malacoma an abnormally soft part or spot.

malacoplakia a circumscribed area of softening on the membrane lining a hollow organ, such as the ureter, urethra or renal pelvis.

m. vesicae a flat yellow growth on the mucosa of the bladder.

malacosis [mal″-ko′sis] malacia.

malacosteon [mal″-kos′te-on] osteomalacia.

maladie [mahl″ah-de′] see mal.

m. du jeune âge du chat feline panleukopenia.

M-5: Malachite green endospore stain of Bacillus anthracis.

From Songer JG, Veterinary Microbiology: Bacterial and Fungal Agents of Animal Disease. Saunders, 2004.

maladjustment syndrome [mal″-just′mnt] see neonatal maladjustment syndrome.

malady [mal′-de] a disease or illness.

malalignment [mal″-līn′mnt] displacement, especially of the teeth from their normal relation to the line of the dental arch.

Malamute, malemute see Alaskan malamute.

malar [ma′lr] pertaining to mala. See also zygomatic, jugal.

m. abscess abscessation at the root of the carnassial tooth (upper fourth premolar in dogs and upper third in cats) may give rise to an inflammatory reaction, then a fistula on the face, below the eye. Called also carnassial abscess, facial abscess, facial sinus. Less often, abscessation of the roots of the lower carnassial tooth (first molar in dogs and in cats) can drain through the skin over the mandible or into the mouth.

m. rash dogs with systemic lupus erythematosus (SLE) sometimes develop a symmetric scaling erythematous lesion over the nose which resembles the change seen in humans with SLE.

malaria see avian malaria.

malaris muscle the cutaneous muscle which depresses the lower eyelid.

Malassez named after L.C. Malassez (1842–1909), a French physiologist.

M. disease cyst of the testis.

M. epithelial rests epithelial remnant in the periodontal membrane; sometimes develops into a dental cyst.

Malassezia [mal″-se′zh] a lipophilic yeast which is commonly found on the skin and particularly in normal and diseased ears of dogs and cats. Includes M. pachydermatis, M. canis. Called also Pityrosporum canis.

M. furfur (syn. P. orbiculare, P. ovale) causes a tinea versicolor, a fungal dermatomycosis on the teats of goats.

malasseziasis [mal″-se′zh sis] infection with the yeast, Malassezia. In dogs and rarely cats, skin and ear infections occur, usually secondary to allergic skin disease or an underlying systemic disease, resulting in overgrowth of yeasts which are otherwise normal inhabitants. There is alopecia, erythema, seborhea, and intense pruritus; with chronicity, the skin becomes hyperpigmented, hyperkeratotic and lichenified.

malassimilation [mal″-sim″-la′shn] 1. imperfect, faulty or disordered assimilation. 2. the inability of the gastrointestinal tract to take up one or more ingested nutrients, whether due to faulty digestion (maldigestion) or to impaired intestinal mucosal transport (malabsorption).

malate [ma′lāt] a salt of malic acid.

M-6: Malassezia pachydermatis from a dog ear (modified Wright-Giemsa stain).

From Gotthelf LN, Small Animal Ear Diseases, 2nd Edition. Saunders, 2005.

M-7: Malasseziasis in a West Highland white terrier.

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

m.–aspartate shuttle system for the transfer of reducing equivalents as NADH and H+ between the site of generation in glycolysis in the cytosol and the site of oxidation in the electron transport chain for production of ATP in the mitochondria. Reducing equivalents are transported into the mitochondria as malate, using oxaloacetate as the carbon carrier. The oxaloacetate is generated from transamination of aspartate. Oxaloacetate does not have a mitochondrial transport protein.

m. dehydrogenase, NAD-linked malate dehydrogenase an enzyme found in the mitochondria (as part of the TCA cycle) or cytosol that participates in the reversible conversion of malate to oxaloacetate.

malathion [mal″-thi′on] one of the least toxic and most widely used organophosphorus insecticides in companion animals. Toxicity when it occurs is usually due to gross overconcentration of the compound in the topical preparation used. See also organophosphorus compound.

malaxate [mal′k-sāt] to knead, as in making pills.

malaxation [mal″k-sa′shn] an act of kneading.

maldescent faulty descent of the testicle into the scrotum.

maldevelopment [mal″d-vel′p-mnt] abnormal growth or development.

maldigestion [mal″di-jes′chn] incomplete digestion such as occurs in pancreatic exocrine or bile salt deficiency. In ruminants a defect in ruminal microflora could have the same effect. See also malassimilation.

maldronksiekte Afrikaans term for poisoning with Solanum kwebense. Literal translation is ‘mad drunk disease′.

male [māl] an individual of the sex that produces spermatozoa.

m. castrate see barrow, capon, gelding, steer, wether.

m. feminizing syndrome see feminizing syndrome.

m. genital system is comprised essentially of penis, prepuce, scrotum, testes, epididymides, vasa deferentia, prostate, seminal vesicles, bulbourethral glands and the male urethra.

m. pseudohermaphrodite see pseudohermaphrodite.

m. sex hormones testosterone is the most important male hormone. Weaker androgens are androstenedione and dihydroepiandrosterone.

maleberry see Lyonia ligustrina.

maleic hydrazide used experimentally to control the growth of grass without killing it. May cause vomiting in dogs walking in the grass.

maleruption [mal″-rup′shn] see teeth maleruption.

malformation [mal″for-ma′shn] defective or abnormal formation; deformity; an anatomical aberration, especially one acquired during development.

malic acid [ma′lik] a dicarboxylic acid that is found in the juices of many fruits and plants, and is an intermediate in the tricarboxylic acid cycle.

malic enzyme [ma′lik] an adaptive enzyme involved in lipogenesis. Catalyses the irreversible conversion of malate to pyruvate + CO₂ in the cytosol. Called also the NADP-linked malate dehydrogenase.

malignancy [m-lig′nn-se] a tendency to progress in virulence. In popular usage, any condition that, if uncorrected, tends to worsen so as to cause serious illness or death. Malignant neoplasia is the best known example.

malignant [m-lig′nnt] tending to become progressively worse and to result in death; having the properties of anaplasia, invasiveness, virulence and metastasis; said of tumors and fulminating infections.

m. aphtha see contagious ecthyma.

m. carbuncle a form of anthrax in humans.

m. fibrous histiocytoma a rare aggressive tumor of dogs and cats; composed of densely packed fibroblasts and histiocytes.

m. head catarrh malignant catarrhal fever.

m. histiocytosis see malignant histiocytosis.

m. hyperthermia see malignant hyperthermia, porcine stress syndrome.

m. lymphoma tautology for lymphoma; all lymphomas are malignant.

m. pustule see malignant carbuncle (above).

m. theileriosis theileriosis caused by Theileria hirci.

malignant catarrhal fever (MCF) [m-lig′nnt k-tahr′l fe′vr] an acute highly infectious, fatal herpesvirus disease of cattle, farmed deer and occasionally pigs characterized by an erosive stomatitis and gastroenteritis, erosions on the mucosa of the upper respiratory tract, keratoconjunctivitis, encephalitis, lymphadenopathy and lymphoproliferative vasculitis in multiple tissues. There are at least two viruses involved both of which cause inapparent infection in their reservoir hosts. A wildebeest-associated form of the disease is caused by alcephaline herpesvirus 1. It occurs in most African countries in cattle which co-mingle with clinically normal wildebeest and hartebeest. It is epizootic and seasonal. It can also occur in zoological gardens in other countries. Sheep-associated MCF is caused by a poorly characterized virus, presumably ovine herpesvirus 2 (OvHV-2). Cases mostly occur when cattle have had contact with lambing ewes and usually start 1–2 months later. Goats can also act as a source of OvHV-2 infection for cattle. Cases without apparent or recent exposure to sheep do occur but are uncommon. Called also bovine malignant catarrh, malignant head catarrh.

malignant edema [m-lig′nnt -de′m] an acute infection of wounds by Clostridium chauvoei, C. novyi, C. perfringens, C. septicum or C. sordellii. The inflammation causes severe swelling and discoloration of skin and exposed tissues. There may be local subcutaneous emphysema and a frothy exudate, depending on the identity of the invading organism. There is a high fever and a profound toxemia; death follows within a few hours if treatment is not provided. Special occurrences are when a large number of animals are affected at one time. These include involvement of the vulva in recently lambed ewes, of shearing or docking wounds, and of the umbilicus or eyes of recently born lambs.

malignin a protein fragment present in the serum of human patients with malignant glial tumors.

malingerer in human terms, an individual who feigns illness. The word cannot really be applied to animals but is sometimes used as a name for an assortment of otherwise difficult to classify cases, e.g. cows which ‘sulk’ and will not rise even though they probably can, or animals that practice attention–attraction behavior, e.g. dogs feigning lameness.

Malinois see Belgian Malinois.

malkop-ui Dipcadi glaucum.

mallard see Anas platyrhynchos.

malleable susceptible of being beaten out into a thin plate.

m. retractor a flat elongated piece of metal shaped like a tongue depressor, which can be bent into a desired shape and used as a retractor for soft tissue. See ribbon malleable retractor.

mallein [mal′e-in] a substance prepared from Burkholderia mallei (previously Malleomyces mallei and Pseudomonas mallei) that elicits a delayed-type hypersensitivity reaction when injected intradermally as a test for glanders.

M-8: Malignant catarrhal fever, keratoconjunctivitis showing centripetal spread of corneal opacity.