Horse Health Glossary

Not sure what that veterinary word means? Look it up below!

Reprinted with permission from the University of California, Davis, The Book of Horses edited by Mordecai Siegal.

ABIOTROPHY:
Progressive loss of function of a tissue or organ.
ABNORMAL HOST:
A host infected with a parasite normally found in another host species.
ABSCESS:
A walled-off lesion filled with pus.
ACARIASIS:
General term for a mite infestation.
ACCOMMODATION:
Ability of the lens to change its shape in order to focus vision effectively on objects at different distances from the eye.
ACETABULUM:
The "cup" or "socket" portion of the hip joint.
ACETYLCHOLINE (ACh):
Messenger molecule released from axon terminals by a nerve impulse; responsible for transmission of the nerve impulse across the synaptic cleft to the muscle fiber supplied by the nerve.
ACETYLCHOLINESTERASE:
Enzyme capable of breaking down acetylcholine.
ACIDOSIS:
Systemic condition characterized by abnormally acid blood.
ACTIN:
A vital protein component of muscle, one of the proteins responsible for muscle contraction.
ACTINIC KERATOSES:
Single or multiple, firm, elevated, plaque- or papulelike skin lesions that result from excessive exposure to sunlight; considered to be precancerous lesions.
ACTINOMYCOSIS:
Pus-producing diseases caused by bacteria of the genus Actinomyces.
ACTIVE IMMUNIZATION:
Vaccination.
ACUTE:
Of short duration and relatively severe; having a rapid onset.
ADDISON'S DISEASE:
Hypoadrenocorticism; insufficient secretory activity by the adrenal cortex.
ADENOCARCINOMA:
Any malignant tumor originating in glandular tissue.
ADENOMA:
Any benign tumor originating in glandular tissue.
ADENOSINE TRIPHOSPHATE (ATP):
The major form of energy used by cells in the body.
ADHESION:
A fusion or sticking together of surfaces.
ADIPSIA:
The absence of thirst; avoidance of drinking.
ADJUVANT:
Substance that nonspecifically stimulates immune responses; used in inactivated vaccines to prolong the immune response to vaccine components.
ADJUVANT CHEMOTHERAPY:
Use of anticancer drugs following surgical or radiation treatments in an effort to destroy residual (microscopic) tumor cells that may have been left behind.
ADRENAL CORTEX:
The outer layer of the adrenal glands.
ADRENAL GLANDS:
Glands located adjacent to the kidneys, involved in the secretion of several important hormones including cortisol, corticosterone, aldosterone, and epinephrine (adrenaline).
ADRENALINE (EPINEPHRINE):
A hormone secreted by the adrenal glands; it acts to increase blood sugar levels and blood pressure and to accelerate the heart rate.
ADRENOCORTICOTROPIC HORMONE (ACTH):
A hormone produced by the pituitary gland in the brain; it exerts a controlling function over the cortex (external portion) of the adrenal glands.
ADSORB:
To bind to a surface.
ADULTICIDE:
Medication to kill adult worms.
AEROBIC:
Requiring the presence of oxygen to grow.
AEROSOL EXPOSURE:
Exposure to an infectious agent by means of contaminated moisture droplets drifting in the air.
AEROSOL THERAPY:
Treatment in which drug therapy (antibiotic or other compound) is delivered by misting or spraying the drug into the airways, usually by means of a funnel or cone placed over the nose; useful in treating pneumonia and certain other respiratory ailments. Also called NEBULIZATION.
AFRICAN HORSE SICKNESS:
Acute, severe to mild, insect-transmitted disease characterized by fever and signs of cardiac or pulmonary insufficiency; caused by an orbivirus in the Reoviridae family of RNA viruses.
ALANINE AMINOTRANSFERASE (ALT, SGPT):
A liver-cell enzyme; increased levels in the bloodstream are indicative of liver-cell injury.
ALBUMIN:
A major protein component of the blood plasma, important in maintaining osmotic pressure within the blood vasculature and as a transport protein for many substances.
ALDOSTERONE:
A hormone secreted by the adrenal cortex; important in the regulation of sodium and potassium levels and, in turn, in retaining water within the body.
ALGAE (singular: alga):
Single-celled organisms that include seaweed, many fresh-water plants, and certain opportunistic pathogens such as Prototheca.
ALLELE:
An alternative form of a given gene. For each gene there are two alleles, one on each chromosome of a chromosome pair. One allele is inherited from the mother, the other from the father.
ALLERGEN:
Any substance that can induce an allergic reaction.
ALLERGENIC:
Inducing allergy.
ALLERGIC BRONCHITIS:
Allergic inflammation of the bronchi.
ALLERGIC CONTACT DERMATITIS:
An uncommon skin disease caused by a hypersensitivity reaction, as occurs in hikers and backpackers following contact with poison ivy or poison oak.
ALLERGY:
A hypersensitive state of the immune response, wherein exposure to a particular substance (an allergen) results in a noxious and sometimes physically harmful immunologic response.
ALLOGRAFT:
Tissue graft obtained from an individual of the same species as the recipient.
ALOPECIA:
Absence or loss of hair.
ALVEOLI (singular: alveolus):
Small air sacs comprising the innermost structure of the lungs. It is through the delicate walls of the alveoli that gas exchange occurs between the blood (flowing through the pulmonary capillaries) and the inhaled or exhaled air.
AMBULATORY:
Involving locomotion; able to walk.
AMINO ACIDS:
Nitrogen-containing molecules that form the structural backbone of proteins. All amino acids contain both an amino group (NH2) and a carboxyl group (COOH).
AMMONIA:
A waste product of protein metabolism; normally excreted through the kidneys.
AMNION:
The placental membrane immediately surrounding the foal.
AMYLASE:
Enzyme produced by the salivary glands and pancreas that breaks down carbohydrates.
AMYLOID:
An insoluble protein substance that causes disease (amyloidosis) when deposited in large quantities in tissues.
AMYLOIDOSIS:
Disease process characterized by deposition of amyloid in various tissues of the body, including the kidneys.
ANABOLISM:
The body's conversion of simple substances to more complex compounds.
ANAEROBIC:
Able to grow in the absence of oxygen.
ANAGEN:
The phase of hair follicle activity during which hair is actively being produced.
ANAL SPHINCTER:
The circular band or ring of muscle that controls the release of feces from the anus.
ANALGESICS:
Pain-killing medications.
ANAMNESTIC RESPONSE:
Immunologic memory; the ability of the immune system to "remember" a foreign substance to which it has been exposed, and to produce an even more effective response to it upon subsequent reexposure.
ANAPHYLACTIC REACTION (ANAPHYLAXIS):
A rapidly developing, exaggerated (and sometimes life-threatening) allergic reaction.
ANATOMY:
The study of body structure.
ANDROGEN:
Male sex hormone; e.g., testosterone.
ANEMIA:
Low red blood cell count, reduced hemoglobin levels, or reduced volume of packed red cells.
ANESTRUS:
The sexually inactive period between two estrus cycles.
ANGIOEDEMA:
Recurrent wheals or welts in the skin, caused by dilation and/or increased permeability of capillaries.
ANGIOGRAPHY:
The radiographic visualization of blood vessels, accomplished by the intravenous injection of a contrast medium that allows the shape and course of the vessels to be delineated on X-ray examination.
ANGIOSARCOMA:
Tumor of blood or lymphatic vessels.
ANKYLOBLEPHARON:
Failure of one or both eyelids of the newborn to open at the appropriate time.
ANKYLOSIS:
The immobility and consolidation of a joint, secondary to trauma, infection, or surgery.
ANNULAR LIGAMENTS:
Ligaments that function to maintain tendon alignment where the tendons cross a joint.
ANORECTIC:
Having no appetite.
ANOREXIA:
Loss of appetite; inappetence.
ANTEMORTEM:
Before death.
ANTERIOR CHAMBER:
The fluid-filled space at the front of the eye, situated between the cornea and the iris.
ANTERIOR UVEA:
The iris and ciliary body of the eye.
ANTERIOR UVEITIS:
Inflammation of the iris and ciliary body of the eye.
ANTHELMINTIC:
Any deworming medication.
ANTHRAX:
A rapidly fatal illness caused by multiplication and spread of the bacterium Bacillus anthracis following ingestion of the bacterial spores.
ANTIBIOTIC:
A chemical substance produced by microorganisms that is capable of inhibiting or killing other microorganisms; many antibiotics are used medically for the treatment of serious bacterial infections. Examples of antibiotics include penicillin, tetracycline, and gentamicin.
ANTIBIOTIC SENSITIVITY TESTING:
Laboratory test procedure for identifying the sensitivity or resistance of a bacterial isolate to several antibiotics.
ANTIBODIES (IMMUNOGLOBULINS):
Specialized proteins produced by cells of the immune system in response to the presence of foreign material (bacteria, viruses, toxins, etc.); antibodies are capable of binding to the foreign material and thus alerting other immune cells to its presence.
ANTICOAGULANT:
Chemical that prevents blood from clotting.
ANTIDIURETIC HORMONE (ADH):
Pituitary gland hormone that controls water resorption by the kidneys, urine production and concentration, and water balance; also called vasopressin.
ANTIEMETICS:
Medications for controlling vomiting.
ANTIFUNGAL:
A chemical substance produced by microorganisms or by other means, useful in the treatment of fungal infections.
ANTIGEN:
A substance capable of inducing a specific immune response in the body, by binding to a specific antibody; can be a property of bacteria, viruses, other foreign proteins, or even host tissue cells.
ANTIGENIC:
Having the properties of an antigen.
ANTIMICROBIAL:
Killing or suppressing the growth of microorganisms; also, any antibiotic or antifungal medication.
ANTINUCLEAR ANTIBODY (ANA) TEST:
Test that detects autoantibodies against the DNA of cell nuclei; used as an aid in the diagnosis of systemic lupus erythematosus (SLE, lupus).
ANTIOXIDANTS:
Substances such as vitamin E and selenium that protect cells against damage caused by by-products of normal metabolic processes.
ANTISERUM:
Serum that contains high levels of antibodies specific for a particular antigen of interest.
ANTISPASMODICS:
Medications to prevent spasms of the gastrointestinal tract.
ANTITUSSIVES:
Cough suppressants.
ANURIA:
Complete cessation of urine production.
AORTA:
The great vessel arising from the left ventricle of the heart, that feeds blood through the arterial system into the body.
AORTIC STENOSIS:
Constriction (abnormal narrowing) of the connection between the left ventricle and the aorta.
AORTIC VALVE:
The semilunar valve on the left side of the heart; also called the aortic semilunar outflow valve.
APLASIA:
Imperfect development or absence of a tissue or organ.
APNEA:
Cessation of breathing.
APOCRINE CYST:
Cyst caused by obstruction of a sweat gland.
APOCRINE SWEAT GLANDS:
Sweat glands that empty their contents into an associated hair follicle.
APPENDICULAR SKELETON:
That portion of the skeleton composed of the bones forming the limbs and pelvis.
AQUEOUS HUMOR:
The fluid occupying the anterior and posterior chambers of the eye.
ARABIAN FADING SYNDROME:
Juvenile Arabian leukoderma.
ARACHIDONIC ACID:
An essential fatty acid found in animal fats; a precursor in the biosynthesis of compounds such as the prostaglandins.
ARBORIZE:
To branch.
AREA CENTRALIS:
Specialized area of the retina, near the optic disc, that possesses an abundance of cone photoreceptors and is largely responsible for the most precise and accurate vision.
ARGASID TICKS:
Soft-bodied ticks; distinguished from ixodid (hard-bodied) ticks.
ARRHYTHMIA:
Any abnormal irregularity of the heartbeat caused by an electrical disorder in the heart.
ARTERIES:
Thick, muscular vessels that drive oxygenated blood from the heart toward the tissues.
ARTERIOLES:
Small arteries.
ARTERITIS:
Inflammation of an artery.
ARTHRITIS:
Joint inflammation.
ARTHROPATHY:
Any joint disease.
ARTHROPOD:
An invertebrate organism with a hard outer skeleton (exoskeleton) and a segmented body; examples include insects, spiders, and crustaceans.
ARTHROSCOPIC SURGERY:
Surgery using a tubular instrument (arthroscope) for examining and carrying out surgical procedures within a joint, without the need for an extensive incision.
ARTHROSPORES:
Infective units of the filamentous mold form of the fungal pathogen Coccidioides immitis, the cause of coccidioidomycosis ("valley fever").
ARTICULAR CARTILAGE:
Cartilage found within joint structures.
ARTICULATE:
To connect at a movable joint.
ASCARIASIS:
Any ascarid infestation.
ASCARID:
A type of roundworm.
ASCITES:
The accumulation of fluid within the abdominal cavity.
ASCORBIC ACID:
Vitamin C.
ASPARTATE AMINOTRANSFERASE (AST, SGOT):
A liver-cell enzyme that is also found in muscle cells and red blood cells.
ASPERMOGENESIS:
Failure to produce sperm.
ASPHYXIA:
Suffocation.
ASPIRATE:
The removal of fluid from a tissue or cavity by means of a syringe and needle.
ASPIRATION PNEUMONIA:
Pneumonia caused by accidental inhalation of food or other material into the lungs.
ASPIRATION SMEAR:
Diagnostic procedure in which fluid, containing cells, is withdrawn from a tissue or body cavity and then smeared onto a glass microscope slide for examination.
ASYMPTOMATIC:
Not exhibiting clinical signs.
ATAXIA:
Incoordination.
ATHEROSCLEROSIS:
Vascular disease associated with high blood pressure and high cholesterol and fats in people; exceptionally rare in animals.
ATOPIC DERMATITIS:
Heritable hypersensitivity to pollens or other environmental allergens, which results clinically in immunologic and inflammatory reactions in the skin.
ATOPY:
An inherited predisposition toward the development of allergy.
ATRESIA:
Congenital absence or occlusion of an orifice or tubular organ.
ATRIAL FIBRILLATION:
Arrhythmia characterized by irregular, disorganized, chaotic changes in the electrical activity of the upper chambers of the heart, resulting in abnormal contractions.
ATRIAL SEPTAL DEFECT:
Rare congenital defect characterized by the presence of a hole in the wall or septum separating the left and right atria of the heart.
ATRIOVENTRICULAR (AV) NODE:
The heart region electrically connecting the atria and ventricles; it slows the conduction of the depolarization wave so that a short period of time is interposed between atrial and ventricular contractions.
ATRIOVENTRICULAR (AV) VALVES:
The heart valves that separate each atrium from its corresponding ventricle
ATRIUM (PLURAL: ATRIA):
One of the two upper chambers of the heart.
ATROPHY:
Shrinking or wasting of a tissue or organ.
ATROPINE:
An alkaloid drug that relaxes smooth muscle, increases the heart rate, and in the eye causes dilation of the pupil.
AUDITORY OSSICLES:
Tiny bones in the middle ear that are responsible for transmitting the vibrations of the eardrum to the inner ear.
AURAL FLAT WARTS (AURAL PLAQUES):
Skin warts found on the ears of horses greater than a year of age; caused by a papillomavirus.
AUSCULT, AUSCULTATE:
To listen to the inner sounds of the chest or abdomen with the aid of a stethoscope.
AUTOANALYZERS:
Automated equipment for performing serum chemistry panels.
AUTOANTIBODY:
An antibody directed against "self," i.e., against the body.
AUTOIMMUNE RESPONSE:
An inappropriate immune response, directed against the body's own tissues.
AUTONOMIC NERVOUS SYSTEM:
That part of the nervous system involved in the regulation of the heartbeat, glandular secretions, and smooth muscle contraction and relaxation, and generally not subject to conscious control.
AUTONOMOUSLY:
Uncontrollably.
AUTOSOMAL:
Referring to any of the chromosomes excluding the sex chromosomes.
AVERSION CONDITIONING:
Learned avoidance of unpleasant situations, such as an encounter with an electric fence.
AVIDIN:
A constituent protein of egg whites that can impair absorption of the vitamin biotin.
AVULSION:
A pulling or tearing away.
AXIAL SKELETON:
That portion of the skeleton composed of the skull, vertebrae, ribs, and sternum (breastbone).
AXILLARY NODULAR NECROSIS:
Uncommon, sporadic skin disease characterized by the development of nodules in the axillary region ("armpit").
AXON:
The fingerlike extension of a nerve cell, along which the nerve impulse travels.
AXON TERMINALS:
Branchings of a nerve axon within muscle, forming neuromuscular junctions with the myofibers supplied by the nerve.
AZOTEMIA:
An elevation of blood urea nitrogen (BUN) and creatinine levels in the bloodstream.

Free Newsletters

Sign up for the latest in:

From our partners