Definitions of words commonly used in veterinary terms




A -

AAFCO: Association of American Feed Control Officials; an organization which sets standards for pet food ingredients and minimum daily requirements.

Acid: A fluid containing a high proportion of hydrogen ions, giving the liquid a sour taste. Measured by pH units, with 1 the most acid, and 14 the least acid. Chemical reactions in the body have to take place at or near neutrality, pH 7.

ACTH: Adrenocorticotropic hormone. A hormone, secreted by the pituitary gland, which stimulates the adrenal gland to work.

Active Immunity: Immunity produced when an animal’s own immune system reacts to a stimulus e.g., a virus or bacteria, and produces antibodies and cells which will protect it from the disease caused by the bacteria or virus. Compare with 'passive immunity'.

Acute: Having a sudden and generally severe onset. See also chronic.

Addisons disease, Addisonian: Addison's disease is also known as hypoadrenocorticism. It is a disease that results from a decrease in corticosteroid secretion from the adrenal gland. See article: Addison's Disease (Hypoadrenocorticism)

Adjuvant: A substance added to killed vaccines to stimulate a better immune response by the body. Common adjuvants contain aluminum compounds.

Adrenal Glands: Two small glands near the kidneys that produce many hormones required for life.

Adrenergic: Communication between the nerves and muscles that uses epinephrine as the 'messenger'. Adrenergic stimulation is what is involved in the 'flight or fight' response, which means the body is alerted to a danger of some sort and prepares to basically run or fight. Adrenergic stimulation results in an increased heart rate, sweating, and increased blood pressure.

Adsorbent: Solid substance which attracts other molecules to its surface.

Aerobic: Needing oxygen to live. See also anaerobic.

Agglutination: Clumping together.

Albino: An animal that is completely white because it lacks the ability to make pigment. Its eyes are pale blue or pink.

Alkaline: A substance with very few hydrogen ions, and a pH over 7. Lye is strongly alkaline.

Alopecia: A loss of hair or baldness.

Alopecic Syndrome, color dilution alopecia: Deficiency of the hair, caused by a failure to grow or regrow after loss. Signs may include bacterial folliculitis, scaling and hair loss. Caused by the dilution gene at the D locus.

Allergen: Substance that causes an allergic reaction, e.g., pollen.

Aminoglycoside: A class of antibiotics which act by interfering with bacterial protein synthesis within the bacteria which results in the death of the bacteria. Antibiotics in this class include gentamicin (Gentocin), kanamycin, neomycin, streptomycin, tobramycin, and amikacin. Many of these antibiotics are not well-absorbed from the animal's digestive system, so are often administered as injections, or used topically.

Amylase: Digestive enzyme, produced by the pancreas which breaks down carbohydrates and starches.

Anabolic steroid: A type of steroid (not a corticosteroid like prednisone, cortisone, or dexamethasone) which promotes the building of tissues, like muscle.

Anaerobic bacteria: Bacteria which only live in an environment in which there is no or little oxygen, e.g. Clostridium tetani which causes tetanus.

Analgesia: pain relief.

Anamnestic response: The faster and greater immune response produced by an animal who has previously encountered that specific antigen. Memory cells are responsible for this more efficient response. Also called 'secondary response'.

Anaphylaxis, Anaphylactic shock, Anaphylactoid: Anaphylaxis is a rare, life-threatening, immediate allergic reaction to something ingested or injected. If untreated, it results in shock, respiratory and cardiac failure, and death.

Androgen: hormone which produces male sexual characteristics, e.g., testosterone

Anaemia: A condition in which the number of red blood cells present in the blood is lower than normal.

Angiotensin-converting-enzyme (ACE) inhibitor: Drug which decreases the function of this particular enzyme. The angiotensin-converting-enzyme changes a compound called angiotensin I to angiotensin II. Angiotensin II is a potent blood vessel constrictor. ACE inhibitors, then, have the effect of dilating blood vessels since less Angiotensin II is produced.

Anorexia: Loss of appetite.

Anthelmintic: Medication which kills certain types of intestinal worms; dewormer.

Antibody: Small disease-fighting proteins produced by certain types of cells called 'B cells'. The proteins are made in response to 'foreign' particles such as bacteria or viruses. These antibodies bind with certain proteins (antigens) on foreign particles like bacteria, to help inactivate them. See also antigen.

Antibody Titer: A measurement of the amount of antibodies in the blood. The test to measure antibodies is usually performed by making a number of dilutions of the blood and then measuring at what dilution there is sufficient antibody to react in the test. For example, a titer of 1:8 (one to eight) means the blood can be diluted to one part blood and seven parts saline and still produce a positive reaction in the test. The higher the titer (1:16 is higher than 1:8), the more antibody is present.

Anticholinergic: Stopping the communications between certain nerves and muscles of the body including those of the gastrointestinal tract and heart. These nerves are called 'parasympathetic' nerves and do such things as constrict the pupils of the eye, stimulate contractions of the muscles in the intestine, and slow the heart rate. Anticholinergic drugs would have the effect, then, of dilating the pupil, slowing contractions of the intestines and increasing the heart rate.

Anticholinesterase: a drug that blocks the enzyme acetylcholinesterase; this results in stimulation of the parasympathetic nervous system.

Anticoagulation: Stopping the blood clotting process.

Anticonvulsant: A drug used to prevent or decrease the severity of convulsions.

Antigen: A molecular structure on surfaces of such particles as bacteria and viruses. This structure is recognized by the body as 'foreign' and stimulates the body to produce special proteins called antibodies to inactivate this foreign invader. See also antibody.

Antiprotozoal: An agent that kills protozoa, which are one-celled organisms such as Giardia.

Antipruritic: Relieves itching.

Antiseptic: A substance which inhibits the growth of bacteria, but does kill them.

Antispasmodic: An agent that relieves or decreases spasms in muscle. The muscle could include 'smooth muscle' which is the type of muscle in intestines that causes them to contract and move food through the digestive system.

Antitussive: Cough suppressant.

Anuria: The condition of complete failure in the function of the kidneys such that no urine is produced.

Aplastic anaemia: A serious condition in which red blood cells, white blood cells and platelets are not produced in sufficient quantity.

Aqueous humor: The fluid found within the eyeball which provides nourishment to the interior eye structures and keeps the eyeball inflated.

Arrhythmia: A variation from normal heart rhythm.

Arthritis: Inflammation of a joint. Caused by abnormal stress on a normal joint, or by normal stress on an abnormal joint. Polyarthritis is immune mediated, and is arthritis in multiple joints.

Ascarid: Roundworm. See article: Roundworms

Ascites: Fluid accumulation in the abdomen.

Aspirate: Withdraw fluid or cells through the use of suction - usually the suction produced by pulling back on the plunger of a syringe attached to a needle which is inserted into the area to be sampled.

Asymptomatic: A term used to decide a condition in which no symptoms are present.

Ataxia: A lack of muscle coordination, usually causing an abnormal or staggered gait.

Atopy: An allergy to something that is inhaled such as pollen or house dust. Also called 'inhalant allergy'. See articles in the Allergies section

ATP: Adenosine triphosphate; a compound used for energy by cells

Atrium (plural atria): The two chambers of the heart that receive blood. The right atrium receives blood from the body. The left atrium receives oxygenated blood from the lungs.

Atrial fibrillation/flutter: A heart condition in which the atria (chambers of the heart that receive the blood) contract rapidly, irregularly, and independently of the ventricles (the chambers of the heart that pump the blood). This greatly decreases the efficiency of the heart and its ability to move blood.

Attenuated: Weakened. An attenuated virus is one which has been changed such that it will no longer cause disease. An attenuated virus would be used in a modified live vaccine.

Autoimmune: Condition in which in the immune system attacks the body's own tissues. To properly function, the immune system must identify foreign substances such as bacteria, viruses, parasites, slivers, etc., and it must be able to distinguish normal body tissue from these foreign substances. If it fails to distinguish the difference it attempts to destroy the tissue it wrongly identifies as foreign. For example, in autoimmune haemolytic anaemia, the body destroys its own red blood cells. In rheumatoid arthritis it attacks the cells in the joints.

Autoimmune Disease: Failure of the immune system to differentiate the body’s own cells from foreign substances, triggering an inflammatory response against self. This can be in the form of a very specific immune attack, such as the destruction of pancreatic islet cells resulting in diabetes mellitus, or a broad immunologic injury such as lupus.

Autoimmune Hemolytic Anaemia: The body produces antibodies directed against its own red blood cells, causing their destruction. FYI: Many if not all of the autoimmune anaemia's have antibodies that attack related, similar blood types, donor RBC’s too.

Autosomal: Any of the chromosomes other than the sex pair, the ‘X’ or ‘Y’ chromosomes. benign – not cancerous or malignant.

B -

Bacteriocidal: A description of an agent that kills bacteria.

Bacteriostatic: A description of an agent that stops the growth (reproduction) of bacteria, but does NOT kill them.

B cell: Also called 'B lymphocyte'. The type of lymphocyte which produces antibody. Compare with 'T cells'.

Benign: A mild illness or non-malignant form of cancer.

Beta blockers: Heart medications which block certain receptors in the heart called beta receptors. The beta receptors receive signals which generally increase the heart rate. If the heart rate is abnormally fast and uneven, beta blockers will help stabilize the rate and rhythm of contractions.

Beta-carotene: A plant pigment which can be converted to Vitamin A by many animals, but not by cats.

Beta-lactamases: Enzymes produced by some bacteria which inactivate certain types of penicillin thus making the bacteria resistant to them.

Biopsy: Surgical removal of a small amount of abnormal tissue, usually of tumors, for diagnosis.

Blepharospasm: Spasm of the eyelids often resulting in complete closure of the lids due to eye pain, such as seen with a scratch on the cornea.

Bloat: Filling of the stomach with air.

Blood glucose profile (curve): A graph of blood glucose levels over time. At the time of insulin injection, and at regular intervals throughout the day, the level of glucose in the blood is determined through laboratory testing.

Bone marrow suppression: A condition in which the cells of the bone marrow which produce red blood cells, white blood cells and platelets are inhibited. This may result from the use of certain drugs, such as anti-cancer agents.

Borborygmus: The sound of gas moving through the intestine; bowel sounds.

Bradycardia: An abnormal slowing of the heart rate.

Bronchiole: The small airways in the lung that come off of the larger bronchus; bronchioles are 1 mm or less in diameter.

Bronchodilator: Medication which opens up the main air passages to the lungs.

Bronchospasm: Condition in which the muscles surrounding the air passages to the lungs contract, narrowing the passages.

BUN: Short for 'blood urea nitrogen', a blood test that estimates kidney function.

C -

Cachexia: Extreme weight loss.

Calcified: The hardening of tissue through the influx of calcium, usually as a result of chronic inflammation.

Calorie: The unit of measurement of energy derived from digested food. Fat contains about twice as many calories per gram as protein or carbohydrate.

Cancer: A group of diseases caused by transformation of normal cells into malignant ones. When these cells shed and travel to other areas of the body, the cancer is said to metastasize. As the cancerous growth draws nutrients, and the general lack of well-being diminishes the appetite, the resultant emaciation is called cancer cachexia.

Candida: A certain genus of yeast which can cause disease in humans and animals; an infection with Candida is called candidiasis.

Carbohydrate: Compounds made up of chains of sugar units. Simple carbohydrates include table sugar (sucrose), milk sugar (lactose), and fruit sugar (fructose). Complex carbohydrates are very long chains held together by bonds that may not be digestible in the stomach and intestine of a carnivore. Starch is a digestible complex carbohydrate. Seed hulls such as oat bran are digestible by ruminants and horses but not carnivores.

Carcinogen: A substance which causes cancer.

Cardiomyopathy: Diseases of the heart muscle; does not include diseases of the valves of the heart or congenital defects.

Carnivore: An animal whose natural diet includes meat.

Carrier: Animal which harbors an infectious organism, such as a virus, bacteria or parasite. The animal does not appear ill but can still transmit the organism to other animals by direct contact or releasing the organisms (bacteria, protozoa, viruses) into the environment in the stool, urine, respiratory secretions, or vaginal discharges.

Cataract: A cloudiness of the lens of the eye, reducing vision and giving the eye a pearly appearance. Can be genetic or acquired as the result of injury or diabetes, etc. Also associated with PRA which is inherited.

Cecum: A blind sac that opens into the colon of many animals.

Cell-mediated immunity: The immunity that is the result of either special lymphocytes directly killing the foreign invader, or lymphocytes (T cells) releasing special chemicals which activate macrophages to kill the invader. Compare with 'humoral immunity'.

Cervical Vertebral Instability (Wobblers): Compression of the cervical (neck) spinal cord caused by instability or malformation of the cervical vertebrae. Dogs show lack of muscle coordination in the back legs and possibly neck.

Chelation: Binding of a substance to a metal.

Chronic: Of a long duration: a chronic illness persists for weeks, months, or even for the life of animal. See also acute.

Chronic superficial keratitis: A chronic condition of the eye in which blood vessels grow across the cornea (the clear surface of the eye). The cornea looks hazy and sometimes reddened; it may eventually take on a dark pigment. This condition is also called pannus.

Chondroprotective nutraceutical: A nutritional supplement that protects cartilage.

Class I,II,III,IV medications: Drugs are classified by the Drug Enforcement Administration of the Department of Justice depending upon such criteria as the potential for human abuse.

Cleft Palate: A congenital split involving the hard or soft palate in the mouth. May cause nasal regurgitation in newborns. Known to be inherited in some breeds, may also be caused by environmental factors.

Clotting factors: Protein components in the blood which help it to clot. Clotting is a complex mechanism. In addition to platelets, clot formation is the result of a long chain of chemical reactions carried out by individual molecules called 'clotting factors'. Each factor is numbered such that factor I leads to a reaction with factor II forming a new substance. This then reacts with factor III and so on to factor XII.

CNS: Central nervous system. Includes the brain, spinal cord, and the nerves leading from them.

Coagulation: The process of clotting.

Coccidia: A one-celled parasite in the category of protozoa. In dogs and cats, coccidia are generally parasites of the intestinal tract. See article: Coccidia

Cognitive dysfunction: A common medical condition in older dogs that results from abnormal brain function, causing certain behavior changes such as disorientation, housebreaking problems, and changes in sleeping patterns and interactions with others.

Colitis: An infection or inflammation of the colon.

Colostrum: The antibody-rich first milk produced immediately before and after giving birth.

Coma: Being in a state of unconsciousness.

Comedo: A blackhead, usually the result of a plugged gland within the skin.

Conception: The onset of pregnancy, when the fertilized egg attaches to the uterus.

Congenital: A characteristic of an animal that is present at birth. It may be inherited or induced by events that occur during pregnancy.

Corticosteroid: Hormones produced by the adrenal gland which are important to almost every function of cells and organs. They are divided into two groups: glucocorticoids and mineralocorticoids. Glucocorticoids regulate protein, carbohydrate and fat metabolism. Mineralocorticoids regulate electrolyte balances.

Coumestan and coumestrol: Estrogen-like substances produced by certain plants such as alfalfa; types of phytoestrogen.

Cruciate: Shaped like a cross. Cruciate ligaments are found on the front (cranial or anterior) and the back (caudal or posterior) of the stifle (knee) joint.

Cryptorchid: An animal with one or two undescended testicles.

Culture: The process in which a sample of fluid or tissue is taken from an animal and placed in special media which allows the bacteria, virus, etc. to grow (reproduce) in the laboratory.

Cushing’s disease: The pituitary gland produces a hormone that triggers the adrenal gland to produce corticosteroids. If there is a problem with the adrenal gland, or a pituitary tumor, the process breaks down and too much corticosteroids are produced.

Cyanosis: Bluish or greyish color to the skin and gums which occurs when the animal has insufficient oxygen.

Cyst: An abnormal sac structure containing fluid.

Cytokines: Compounds produced by certain cells, which act as messengers to control the action of lymphocytes and other cells in an immune response.

Cytoplasm: Substances which make up the inside of a cell and surround the nucleus of the cell which contains the genetic material.

D -

DEA: Drug Enforcement Administration. The federal agency which regulates the manufacture, dispensing, storage and shipment of controlled substances including medications with human abuse potential.

Dermatitis: An inflammation of the skin.

Dermatophyte: Fungus that causes ringworm; include Trichophyton, Microsporum and Epidermophyton.

Descenting: The removal of the anal sacs of a carnivore to prevent the animal from releasing the very strong-smelling secretion.

Diabetes: A metabolic disease caused by failure of the pancreas to produce insulin, a hormone that allows blood sugar (glucose) to be taken up by cells that require it for function.

Diabetes Insipidus: Inadequate secretion of, or resistance to the effects of, antidiuretic hormone (ADH or Vasopressin). This hormone stimulates the kidney retain water in the body. Consequently, the dog passes a large volume of urine with a low specific gravity, and also exhibits great thirst. It may be acquired, inherited, or idiopathic. mellitus – due to a failure of the pancreas to produce sufficient insulin, or the cells resistance to the effects of insulin the body is unable to properly process glucose. May require insulin injections, or may be controlled with diet. May be acquired or possibly inherited.

Diestrus (also Diestrous): The stage of the estrus cycle which occurs after the animal goes out of heat.

Dietary indiscretion: Eating what one shouldn't. Dogs with dietary indiscretion eat garbage, dead fish on shore, etc.

Digestibility: Expressed as a percent, is a measure of the content of food that is retained in the body after food is eaten. The difference between the weight of food eaten and the weight of stool produced, divided by the weight of the food.

Digitalis glycosides: Class of drugs including digitoxin and digoxin, which are drugs derived from the Digitalis purpurea plant, and used in the treatment of congestive heart failure.

Dilated cardiomyopathy: A heart condition in which the heart enlarges but the heart muscle becomes thinner.

(Canine) Distemper: A viral disease that caused a severe and often fatal systemic illness in dogs and their close relatives. Distemper is also fatal in animals such as raccoons, and mustelids including skunks, mink and ferrets.

Diuretic: Agent which increases the secretion of urine, ridding the body of excess fluid.

Domestic Animal: An animal that has been housed and fed by man for generations and has little fear of man as a result. Some domestic animals learn to depend on human provision so completely that they have little ability to survive if returned to a natural habitat.

Duration of immunity: Length of time an animal is protected from a disease. Vaccines for some diseases provide long durations of immunity (years), while vaccines for some other diseases only provide immunity that lasts for 6 months.

Dysfibrinogenemia, Factor I Deficiency: Fibrinogen, or Factor I, is an important component of the "clotting cascade" which allows your body to stop bleeding. This disease is due to either an abnormally low amount of fibrinogen, or its complete absence, or the presence of a normal amount of an abnormal and less effective fibrinogen. Symptoms include easy or excessive bleeding or no symptoms at all.

Dysplasia: An abnormal tissue development, common in the bones of the canine.

Dystocia: Difficult birth.

E -

Ear Canal: The tube that connects the external ear with the ear drum.

Ear Drum: The membrane that divides the outer ear from the inner ear, where the mechanism of hearing takes place. The membrane prevents infection from reaching the inner ear, as well as vibrating to amplify sounds.

Ear Mites: Small parasitic insects that live in the ear canal of an animal, and that are able to survive outside the ear for only very short periods of time.

Echocardiogram: The image produced by performing an ultrasound examination of the heart.

Ectoparasite: A parasite that lives on the outside surface or skin of another animal. Ectoparasites include fleas, ticks, lice, and mange mites.

Ectopic: Non-malignant tissue growing in an unusual location (e.g., an ectopic pregnancy is conception of a normal embryo outside the normal location, which is the uterus).

Ectopic Cilia: Hairs on the inside of the eyelids causing irritation to the eye.

Ectropion: Eyelid turns outward. Allows for the accumulation of foreign matter causing eye irritation.

Edema: A condition in which the tissues of the body contain too much body fluid. The fluid accumulation may cause swelling in the affected area.

Electrocardiogram (EKG): A printout of an analysis of the electrical activity in the heart.

Elbow Dysplasia (ED): Asynchronous growth of the bones of the foreleg causing the joint to meet improperly.

Electrolyte: Chemically, an element when dissolved in water, will cause the solution to transmit electricity. In medicine, certain elements in the blood which are critically important to life, including sodium, potassium, chloride, calcium and phosphorous.

Emesis: Vomiting.

Emetic: Agent that decreases or stops vomiting.

Encephalopathy: Any degenerative disease of the brain. Causes include liver disease resulting in build up of toxic by products of metabolism, heavy metal (e.g., lead) poisoning, and loss of blood supply.

Endoscope: A long flexible instrument which can be passed into the body to view various structures through the use of fiber optics.

Enteral feeding: A method to feed an animal in which a tube is placed through the body wall into the intestine, and a nutritious liquid is forced through the tube into the intestine.

Enteritis: An inflammation of the intestines.

Entropion: Eyelids turn inward causing hair to irritate the surface of the eye. Normally requires surgical correction, and sometimes requires multiple surgeries.

Enzymes: Enzymes are special proteins produced by cells which cause chemical changes in other substances, but which are not themselves changed in the process.

EPA: Environmental Protection Agency. The agency of the federal government which licenses pesticides and herbicides.

Epiphora: An overflow of tears upon the cheeks due to a blockage or narrowing of the tear ducts.

Esophageal reflux: a condition in which stomach contents move backward into the esophageus, i.e., heartburn.

Estrogen: A female hormone produced by the ovaries, which results in the onset of estrus.

Estrus: The time when a female animal is fertile and receptive to the male. Also known as a heat period.

Exotic: An animal not native to the geographical area where it is living.

F -

Food and Drug Administration. The federal agency which approves drugs and medications for use in animals and people.

First generation:
A description of medications developed from an earlier form of the medication. First generation medications were developed from the original form of the drug; second generation medications are adaptations of first generation drugs; third generation drugs are adaptations of second generation, etc.

Increased stomach or intestinal gas.

Flea Dip:
A solution made to kill fleas, applied to an animal and not rinsed off, to allow it to have residual action.

Foreign body:
Any abnormal substance within the body. Examples include wood slivers, ingested cloth, balls, glass in the feet, etc.

Fragmented Coronoid Process (FCP):
The coronoid process fragments forming a loose body in the elbow joint, called a joint mouse.

Free radical: Atom which carries an unpaired electron; free radicals can potentially injure cells and may be responsible for numerous age-related diseases.

A drug that kills fungi.

G -

Inflammation of the stomach.

Gastrointestinal tract:
Pertaining to the stomach and intestines. The term 'digestive system' includes the mouth, gastrointestinal tract, anus, pancreas, and liver.


Relating to the gums.

: An oral medication that can be used to control blood glucose levels in some diabetic cats who still have some insulin production.

: Inflammatory disease of the glomerulus, part of the kidney, which filters toxic waste from the blood. Tests of the urine can show a variety of abnormalities. Complete loss of kidney function can occur.

Hormones produced by the adrenal gland which regulate protein, carbohydrate and fat metabolism, and are important to almost every function of cells and organs. They also stabilize cell membranes which is an important part of their function in treating allergic reactions. Also called glucocorticosteroids.

Hormones produced by the adrenal gland which regulate protein, carbohydrate and fat metabolism, and are important to almost every function of cells and organs. They also stabilize cell membranes which is an important part of their function in treating allergic reactions. Also called glucocorticoids.

glucose in the urine. (Also called glycosuria)

A storage form of glucose in the body.

Compounds which serve as the building blocks of cartilage, which covers the ends of bones within a joint. Glucosamine and chondroitin are necessary for the body to make glycosaminoglycans.

A measure of weight. 28 grams = 1 oz, 454 grams = 1 lb.

Gram negative:
A classification of bacteria based upon their lack of retention of a certain stain in the laboratory. The staining quality is based on the structure of the cell wall surrounding the bacteria. This structure of the cell wall influences which antibiotics will kill the bacteria. This laboratory staining method was developed by Hans Gram in 1884.

Gram positive:
A classification of bacteria based upon their uptake of a certain stain in the laboratory. The staining quality is based on the structure of the cell wall surrounding the bacteria. This structure of the cell wall influences which antibiotics will kill the bacteria. This laboratory staining method was developed by Hans Gram in 1884.

The formation of a nodule as a result of inflammation.

H -

H2 antagonist:
A compound which binds (attaches) to the area on a cell at which histamine also binds. By binding at the same site, the antagonist blocks histamine from binding and prevents histamine from producing it's effects, which include the production of stomach acid.

Head pressing:
Pressing the head against a wall or other hard object.

Heart block:
A condition in which the electrical impulses of the heart are not properly conducted from the atria (chambers which receive the blood) to the ventricles (chambers which pump the blood).

A species of parasitic worm that lives and reproduces in the chambers of the heart of an animal. Microscopic, immature worms (microfilariae) circulate in the blood and are taken in by mosquitoes that bite the animal. Microfilariae mature in the mouthparts of the mosquito and infect another susceptible animal bitten by the same mosquito.

Heinz body anaemia:
A condition in which the red blood cells are destroyed and this results in anaemia. The specific type of anemia is called 'Heinz body anaemia' because the red cells develop an abnormality called a 'Heinz body' which can be seen under the microscope. This anaemia can occur as a reaction to certain medications and also in cats who eat onions.

See Packed cell volume.

A mass of blood within the tissues. Generally the result of trauma to the blood vessels or abnormal blood clotting.

Causing the red blood cells to break open.

To bleed excessively; may be the result of injury or blood clotting abnormalities.

: Causing the red blood cells to break open.

: The blood lacks coagulating factors, causing a strong tendency to bleed, and difficulty in getting the bleeding to stop. hepatitis – inflammation of the liver. This can result from a variety of causes including infections (particularly viral), drugs, autoimmunity and genetics. The liver stores and filters blood, secretes bile, converts sugars, processes fat, produces proteins which help to control blood volume, and produces some of the clotting factors. 

: To bleed excessively; may be the result of injury or blood clotting abnormalities.

: Pertaining to the liver.

: An inflammation or infection of the liver.

Hepatocerebellar Degeneration
: Death of liver cells causing poisoning of the white matter of the brain.

Hernia: The protrusion of an organ through an abnormal opening, usually in the abdominal or groin areas.

High titer vaccine: A modified live vaccine that contains a higher number of virus particles than the 'average' vaccine. High titer vaccines can generally elicit an immune system response in young animals who have a maternal antibody level that would prevent them from responding to an 'average' vaccine.

Histamine H2 receptor antagonist: A compound which binds (attaches) to the area on a cell at which histamine also binds. By binding at the same site, the antagonist blocks histamine from binding and prevents histamine from producing it's effects, which include the production of stomach acid.

Hip Dysplasia (CHD, HD): Improper development of the hip joint, typically, the acetabulum (socket) is not deep enough for the femoral head (ball) to fit fully into place.

Histiocytomas: A small wart-like skin growth that will eventually disappear. (Note: NO growths or lumps on a BMD should ever be ignored!)

Histiocytosis: Abnormal appearance of histiocytes in the blood. (Histiocytes are produced by the bone marrow and are normally immobile until stimulated by inflammation. They are a type of antigen presenting cell.)

The organism in or on which a parasite lives. For example, dogs and cats are hosts for fleas and roundworms.

Humoral immunity:
The immunity that is the result of antibody production by B cells. Compare with 'cell-mediated immunity'.

An animal that has parents of two different species, for instance, a mule's mother is a horse and its father is a donkey.

Hydrocephalus (water on the brain):
Accumulation of cerebrospinal fluid in the skull, which diminishes the size of the brain.

: Higher than normal blood glucose level

: Increased level of potassium in the blood.

: An increase of the number of cells within an organ.

: Abnormal increase in the amount of tissue, e.g., a hyperplastic ear would have increased numbers of cells in the ear canal, sometimes to the point of closing off the ear canal. In prostatic hyperplasia, the prostate enlarges due to an increased number of normal, not cancerous, cells.

: Producing an exaggerated, or greater than normal response to a stimulus.

: A type of allergic condition in which the body overreacts to a certain agent such as a bee sting or medication.

: A condition, more commonly seen in cats, in which the thyroid gland produces too much thyroid hormone.

Hypertrophic Osteodystrophy (HOD)
: Inflammation of the growth plates, and can be accompanied by depression, weight loss, and fever. The joints may be swollen and feel hot. Mild cases usually resolve with no lasting ill effects. However, in the rare case of severe HOD, permanent damage to the bone joints can result in limb deformities.

: An increase in the rate and/or depth of respiration such that the body loses too much carbon dioxide.

: Lower than normal blood glucose level

: Lower than normal level of potassium in the blood.

Hypomyelination (Tremblers)
: Reduction in the amount of myelin (cover or sheath) on the nerves. The disease has an early onset, in BMDs is considered to be an autosomal recessive trait.

: Inadequate or defective development of tissue.

: A condition, more common in dogs, in which the thyroid gland does not produce enough thyroid hormone.

I -

: Commonly referred to as jaundice. A yellowing of the tissues, usually as a result of abnormal liver function.

: No known cause

Immune-mediated reaction or disease:
A condition or disease caused by abnormal activity of the immune system in which the body's immune system either over-reacts (e.g., immune-mediated contact dermatitis) or starts attacking the body itself ( e.g., autoimmune haemolytic anaemia). See also autoimmune.

Immune system:
The body's defence system which recognizes infectious agents and other 'foreign' compounds (such as pollen), and works to destroy them.

A condition in which the animal's immune system has been primed and is able to protect the body from a disease-causing agent such as a certain virus or bacteria. An animal could have immunity to one agent, such as parvovirus, but not have immunity to another agent, such as rabies.

The process of rendering an animal protected (immune) against a certain disease. Vaccination is a way to produce immunization. However, just because an animal has been vaccinated (received a vaccine) does not necessarily mean the animal is immune. If the body did not correctly react to the vaccine or if the vaccine was defective, immunity would not occur. No vaccine produces immunity in 100% of the population to which it was given. 'Vaccination' is not the same as 'immunization'.

Reduced function of the immune system of an animal, making it more susceptible to infectious disease. Can be an inherited defect or caused by drugs, radiation or viruses.

A compound which stimulates the immune system to work more effectively to kill bacteria, viruses or cancer cells.

Something, for instance a drug, hormone or virus, that reduces the function of the immune system of an animal.

A term used to describe an invasion of parasites.

: Inability to control urination and/or defecation.

: A condition in which tissue reacts to injury and undergoes changes during the healing process. As an example, a toe with a sliver of wood in it would be inflamed and show the signs of inflammation which include redness, increased temperature, pain, swelling and a loss of or disordered function. The toe is swollen, red, hot, painful, and the animal is reluctant to walk on that toe.

: A trait passed from one generation to the next in the genes from each parent.

: A permanent characteristic that is present because of the genetic make-up of the animal.

: A hormone produced by the pancreas which is necessary for glucose to be able to enter the cells of the body and be used for energy.

Insulin dependent diabetes mellitus (IDDM)
: A form of diabetes in which so little insulin is produced that supplemental insulin must be given for the animal to live. Also called Type I diabetes mellitus.

Insulin resistance
: A condition in which the blood glucose level remains higher than it should at an insulin dosage of 2 units/pound of body weight per day in cats.

Intermediate Host
: In the life cycle of some parasites, the immature form of the parasite must pass through a different type of host (animal, insect, snail, etc.), called the intermediate host, before it can re-enter and infect the type of animal it came from. An example would be heartworms. The adult worm lives in the dog or cat. The immature form, laid by the adult heartworm, is taken up by the mosquito. The immature form develops within the mosquito, and is then reintroduced into another dog or cat where it develops into the mature adult and the cycle repeats itself. The intermediate host for heartworms, then, is the mosquito.

Intervertebral Disk Disease (IVDD)
: Pain and often paralysis resulting from displacement of the center of a vertebral disk.

: An action taking place within a cell.

: Into the muscle (IM).

: Into the nose.

: Into a the blood stream via a vein.

: Inability to control urination and/or defecation.

Intervertebral Disk Disease (IVDD)
: Pain and often paralysis resulting from displacement of the center of a vertebral disk.

: The intestine telescopes on itself, causing a blockage.

Irritable Bowel Syndrome
: Soft or watery faeces, often with mucus. Associated with stress. Also called colitis.

The colored portion of the eye is called the iris. As with humans, dogs' iris colors vary. In the center of the iris is the black opening called the pupil. This opening can be made larger or smaller by muscles called ciliary bodies, that attach to the colored iris, causing it to expand or contract.

A estrogen-like substance produced by pasture plants; a type of phytoestrogen.

J -

The condition in which there is a build up of waste products in the body called bilirubin. Bilirubin is yellow in color, therefore an animal with jaundice will have yellow gums, skin (often seen on the inside flap of the ear), and a yellowish cast to the 'whites' of the eyes. It can occur if a large number of red blood cells are destroyed, the liver is not functioning normally, or the bile ducts are blocked.

K -

See Keratoconjunctivitis sicca.

Keratoconjunctivitis sicca:
Keratoconjunctivitis sicca (KCS) is the technical term for a condition also known as 'dry eye'. It occurs because of inadequate tear production. Symptoms include a thick, yellowish discharge from the eye.

A life-threatening condition in which ketones, which result from the breakdown of fat for energy, accumulate in the blood stream and the pH of the blood decreases.

Killed vaccine:
Vaccines which are made by taking the real, disease-causing viruses (or bacteria), killing them, and putting them into a liquid base. Compare with 'modified live vaccine' and 'recombinant vaccine'.

L -

Producing milk.

Large Intestine:
The lower part of the intestinal tract, usually made up of the colon, cecum and rectum. Bacteria that live harmlessly in the large intestine help to digest complex carbohydrates.

The worm-like offspring of an insect (plural larvae).

A dormant stage of disease; the patient is infected with an organism, but is not yet ill.

A condition in which the numbers of white blood cells in the blood are lower than normal.

Digestive enzyme, produced by the pancreas, which breaks down fat.

Liver: The largest organ in the abdomen, responsible for producing enzymes required for digestion of food, and bile that helps to digest fat. The liver also detoxifies the blood and may be damaged in the process.

Low passage vaccine: A low passage vaccine contains virus particles which have been attenuated, or weakened, less than those in the 'average' vaccine. Low passage vaccines can generally elicit an immune system response in young animals who have a maternal antibody level that would prevent them from responding to an 'average' vaccine.

Luxating Tarsus: Dislocation of the ‘ankle’

Lymph Nodes: Part of the immune system of an animal. Small masses of tissue that contain white blood cells called lymphocytes. Blood from the nearby area is filtered through the lymph node allowing foreign or infectious material to be recognized and destroyed if possible.

Lymphocytes: The class of cells in the body which are responsible for mounting an immune response. Two main types are B cells and T cells

Lymphokines: Chemicals produced by T lymphocytes. Some lymphokines signal macrophages and other phagocytes to destroy foreign invaders.

Lymphoma, Lymphosarcoma: Malignant tumor that arises from cells of the lymphoreticular system. Commonly presents with swollen lymph nodes, masses, enlarged liver or spleen, fevers, weight loss.

M -

A type of phagocyte (cell in the body which 'eats' damaged cells and foreign substances such as virus and bacteria).

Malabsorption/maldigestion syndrome:
A condition involving the intestine in which food may not be properly digested or the nutrients not absorbed.

A process that does harm to nearby tissues. Usually synonymous with cancer, a tumor that grows quickly and spreads both in the original area where it occurred and in remote parts of the body.

Ill health due to dietary deficiency or imbalance.

Pertaining to the breast.

Any of several skin and ear conditions caused by a variety of mites.

See Monoamine oxidase inhibitor

Mast cell tumor:
A nodular growth, usually on the skin, which involves cells (mast cells) which contain large amounts of histamine and normally play a role in allergic reactions. All mast cell tumors in dogs should be considered potentially malignant.

Mastitis: Inflammation of the mammary gland, usually due to bacterial infection.

Mastocytoma (mast cell tumors): A growth of mast cells (cells in the dermis which is directly beneath the outer skin layer, which release histamine to counter allergens). These tumors may become malignant.

Maternal antibody:
Antibody in a newborn animal which the newborn acquired through the placenta or colostrum (the first milk).

When referring to food ingredients, means a ground-up preparation. Chicken meal is ground up chicken, which might include bones and feathers. Meat meal means ground up muscle meat.

: A condition in which the colon enlarges and dilates, which results in faeces accumulating in the colon. Constipation then occurs. This condition is more common in cats than dogs.

: Overly enlarged esophagus causing buildup of food and saliva and regurgitation. Associated with aspirative pneumonia from an early age.

Darkening of the stool due to the presence of digested blood, which indicates bleeding is occurring in the stomach and/or beginning of the small intestine. The faeces generally look black and tarry.

(Immunologic) Memory
: When an animal mounts an immune response against a foreign substance, some cells are created to 'remember' the antigens on that substance. If the animal is again exposed to the substance, these cells will help the body respond much faster and to a higher degree.

: Not a disease, but a symptom, the inflammation of the membranes covering the brain and spinal cord, the meninges. This can be caused by bacteria, virus, fungi, or chemical toxins. 

Metabolic acidosis:
A condition in which the pH of the blood is too acidic because of the production of certain types of acids.

Spread of a tumor from its original location to a remote one, by tumor cells that are carried in the blood.

A condition of the blood in which there are large amounts of methemoglobin which is an altered haemoglobin which does not carry oxygen.

The larval form of some parasitic worms, for example heartworms. These worms do not lay eggs, they produce microfilariae instead.

Compound which kills microfilaria, the immature forms of heartworms which circulate in the blood.

A single-celled life form that is invisible to the naked eye and that may cause disease in man or animals.

Hormones produced by the adrenal gland which regulate the amounts of sodium, potassium and chloride in the blood.

An agent that kills mites.

Parts of the cell which are responsible for providing the cell with energy.

Short for milliliter. A liquid measure, the same volume as a cc. 28 mL = 1 liquid oz.

Modified live vaccine:
Vaccines which are made by taking the real, disease-causing virus and altering (attenuating) it in a laboratory to a non-disease causing virus. Compare with 'killed vaccine' and 'recombinant vaccine'.

Monovalent vaccine:
A vaccine that is manufactured to stimulate the body to produce protection against only one disease, e.g., rabies vaccine. Compare with 'multivalent vaccine'.

Monoamine oxidase inhibitor (MAOI):
Substances that inactivate the enzyme monoamine oxidase which regulates certain transmitter chemicals between nerves. These compounds include certain types of antidepressants and also insecticides containing amitraz (such as Mitaban and Preventic collars).

Motility: movement, e.g., intestinal motility is the muscular contractions of the intestines which move the food from the stomach to the anus.

Breaks down mucous.

A carbohydrate which also contains a hexosamine molecule and is a component of mucous.

See Mucous membranes.

Mucous membranes:
Specialized membrane which covers various passages and cavities exposed to the air such as the mouth, nose, inner portion of the eyelids, vagina. Examination of the mucous membranes can provide important information: if they are dry the animal is likely dehydrated; pale, and the animal may be anaemic or in shock; yellow, and the animal is said to jaundiced due to accumulation of waste products which should be eliminated by the liver.

Multivalent vaccine:
A vaccine that combines two or more components to stimulate the body to produce protection against all the components. Most 'distemper' vaccines for puppies are of the multivalent type, and commonly include distemper, parvovirus, adenovirus cough, hepatitis, and parainfluenza. Compare with 'monovalent' vaccine.

Myasthenia gravis:
Myasthenia gravis is a neuromuscular disease in which there is a failure of the nerves' ability to stimulate and control the actions of certain muscles.

Disease caused by a fungus such as blastomycosis, histoplasmosis and ringworm.

Small pupil size.

Radiograph (x-ray) of the spinal cord taken after a contrasting dye has been injected into the space around the spinal cord.

N -

Convert into a fine spray form.

Abnormal functioning of the kidney.

Destructive to kidney cells.

Abnormal functioning of nerves.

Chemical used as a messenger from one nerve cell to another.

Sterilization by surgical removal of the testicles of a male animal.

Animals that are active during the night and sleep during the day.

Non-insulin dependent diabetes mellitus (NIDDM):
A type of diabetes mellitus in which although the blood glucose levels are higher than normal, they are not immediately life-threatening, and the animal can survive without supplemental insulin. Also called Type II diabetes.

Not causing disease. Some bacteria, such as those that normally live in an animal's intestines, are nonpathogenic.

A condition not caused by an infection. For example, septic arthritis is caused by an infection with bacteria, yeast or other agent; a case of nonseptic arthritis may be caused by injury or cancer

Non-steroidal anti-inflammatories (NSAIDS):
Agents which reduce inflammation but are not in the class of drugs known as steroids. Examples include aspirin, Rimadyl and phenylbutazone.

A very broad term describing certain components in food (plant or animal) or nutritional supplements, which contain substances normally present in the body that aid in the proper functioning of body systems.

Compounds in foods which are essential for life. Nutrients include protein, fats, vitamins, minerals, etc.

Constant involuntary movement of the eye, often from side to side

O -

Obligate Carnivore:
An animal that requires in its diet nutrients that are found in sufficient quantities only in meat or other animal products.

Obsessive compulsive:
A behavioral condition in which a pet repeatedly performs an action out of context. It is thought that the behavior is an expression of stress, frustration and/or conflict. Certain breeds more prone to these behaviors. The behaviors include tail-chasing, some cases of excessive barking, continual licking, and biting the air as if snapping at an invisible fly.

Animal organs rejected at slaughter as unfit for human consumption, e.g. spleen, intestine, brain, lungs.

Off label:
Term used to describe the use of a medication for a condition for which it was not FDA approved. A large number of medications used in veterinary medicine are used 'off label'. If veterinarians only used FDA approved medications, options for treatments of certain conditions would be severely limited or nonexistent. The safety and efficacy of off-label uses of medications is often determined in university research settings, but the manufacturer of the drug does submit the results or go through the elaborate FDA approval process.

Opioid: Narcotic drug which has an activity similar to that of opium.

Optic Nerve Hypoplasia: Incomplete development of the optic nerve.

Oral hypoglycemic agent: A medication, given by mouth, which lowers the level of glucose in the blood. Example: glipizide

Osmotic diuretic: A compound that increases the amount of urine formed and rids the body of excess fluid by being filtered through the kidney into the urine in concentrated amounts and carrying water with it.

Osteochondritis Dessicans (OCD): A piece of cartilage tears away forming a flap. The flap may reattach to the bone on its own, or it may tear away, becoming a joint mouse in the joint cavity. Symptoms include pain and limping. Often requires surgery.

Pertaining to the ear.

Destructive to the structures of the ear.

Over the counter:
Can be purchased without a prescription, like aspirin and vitamins.

The release of an egg from the ovary of the female.

P -

Packed cell volume (PCV, hematocrit):
A laboratory test to monitor relative number of red blood cells present in the blood. A blood sample is placed in a tiny glass tube and spun in a centrifuge. The cells are heavier than the plasma and are compacted at one end of the tube. After the tube is spun, it is examined and the packed cell volume is determined as the percentage of the red cellular portion relative to the total amount of blood in the tube (i.e. remainder being the plasma). The normal for dogs is 40-59 and cats is 29-50.

To examine with the hands or fingers.

Pancreatitis: Inflammation of the pancreas, a severe and sometimes life threatening disease often associated with eating fatty foods. Symptoms include vomiting and a painful abdomen. The pancreas produces enzymes and bicarbonate important in digestion and absorption of nutrients as well as insulin. Chronic, severe pancreatitis can result in malabsorption and diarrhea as well as diabetes mellitus.

Pannus: A chronic condition of the eye in which blood vessels grow across the cornea (the clear surface of the eye). The cornea looks hazy and sometimes reddened; it may eventually take on a dark pigment. This condition is also called chronic superficial keratitis.

Panosteitis (pano): Inflammation of the bone, particularly the long bones in growing dogs. Causes pain and limping.

Parasympathetic nervous system: The portion of the nervous system which stimulates the pancreas to produce digestive enzymes and stimulates many of the smooth muscles in the body including those of the stomach and intestine. It also tends to slow the heart rate.

A term used to describe the administration of a drug by means other than by mouth.

act of giving birth.

Passive immunity:
Immunity produced by providing an animal with antibodies or immunologic cells from another source, such as colostrum. Compare with 'active immunity'.

Patellar Luxation: Dislocation of the ‘knee’ cap, causing mild to severe, continuous or intermittent pain.

Patent Ductus Arteriosus (PDA): The normal opening between the aorta and pulmonary artery, which allows blood to bypass the unoxygenated lung in utero, fails to close after birth.

Pathogenic: Causing disease.

See Packed cell volume.

: An infestation of lice.

Pemphigus Foliaceus
: A generalized scaling disease, with hair loss, and sometimes with the formation of heavy crusts. Involvement of a nail bed leads to loss of the nail.

An enzyme produced by some bacteria which inactivates certain types of penicillin thus making the bacteria resistant to them.

Perianal fistula:
A deep infection around the anus which often results in ulcers and deep draining tracts, most commonly seen in German Shepherds.

The area between the anus and the genital organs.

Cell in the body which 'eats' damaged cells and foreign substances such as virus and bacteria. A macrophage is a type of phagocyte.

The number of hours of light per 24-hour period.

A condition in which the skin reacts abnormally to light, especially ultraviolet light or sunlight. It is usually caused by the interaction of light with certain chemicals in the skin such as antibiotics, other medications, hormones or toxins.

Substances in plants which affect a body system and may promote health and decrease the risk of a disease such as cancer.

Substances which have an activity similar to estrogens and are produced by plants.

Pica: Chronic eating of non-food materials.

Placebo: A substance which is given that has no therapeutic value; often called a 'dummy pill' or 'sugar pill'. Often given to half of the patients in a trial of a new drug, to better assess the effectiveness of the new drug.

Plantigrade stance:
Standing and walking with the hocks on or almost touching the floor.

A build-up of bacteria, saliva and food on the teeth. See also 'Tartar'.

Cellular components found in the blood which help clots to form. In the body, microscopically small vessels often break in the normal course of events. Platelets and a protein called fibrinogen 'plug' the break in the vessel and prevent blood from leaking out.

Arthritis which involves two or more joints.

The presence of extra toes.

Excessive thirst resulting in excessive drinking

During one sexual season, continuing to come into heat if not bred. Cats are polyestrous, dogs are not.

A small growth from mucous membranes such as those lining the nasal cavity and intestinal tract.

Excessive ingestion of food

Polyuria: Excessive urination

Portosystemic Shunt (PSS): Abnormal blood vessels in the liver preventing normal circulation and functioning of the liver.

After surgery.

(also Proestrous): The stage of the estrus cycle, right before an animal comes into heat.

: A hormone produced by the ovaries which is responsible for the continuation of pregnancy.

Progressive Retinal Atrophy (PRA): 
Any of a number of inherited diseases of the eye leading to blindness. Generally starts with difficulty seeing in the dark followed by a loss of vision in the daylight.

Hormone secreted by the pituitary gland that stimulates the growth of mammary tissue and the production of milk.

Prolapsed Rectum:
Because of irritation or injury, the inner part of the rectum is pushed out so that it is visible as a pink mass protruding from the anal opening.

Several types of chemicals made by cells which have specific functions such as controlling body temperature, stimulating smooth muscle, and influencing heat cycles.

Protease: Enzyme which breaks down protein.

Single-celled animals invisible to the naked eye. Most are free living and a few are parasites in animals or man.


Pulmonary edema:
Fluid accumulation in the lungs.

Pulmonary emboli/embolism:
Blood clot that travels to the blood vessels in the lung and obstructs them.

A dormant form of an insect (plural pupae). A larva spins a cocoon to protect itself, and becomes a pupa. The pupa does not feed but gradually changes form and becomes a new adult.

Pyloroduodenal obstruction:
An obstruction in the area where the stomach and small intestine meet.

An infection of the skin; usually the result of a bacterial invasion.

Pyometra: An infection of the uterus.

Q -

A female cat used for breeding.

In cats, the act of giving birth.

R -

A fatal virus disease of warm blooded animals including man, that affects the brain and is spread in the saliva of infected animals. Rabid animals have a temperament change. Wild creatures become bold enough to attack human beings, and docile domestic animals may turn on their owners.

Reagent grade
: A compound with the purity and quality that allows it to be used in a laboratory

: Requires a copy of the gene from both parents to exhibit the trait. Having only one copy of the gene makes the dog a carrier of the trait, and he will never exhibit the trait – unless the gene is located on the ‘X’ or sex chromosome. sarcoma – tumor formed of connective tissue cells: bone cartilage, muscle, blood vessel, or lymphoid tissue.

Recombinant vaccine:
There are certain antigens on viruses and bacteria which are better at stimulating an antibody response by the animal than others. The genes for these antigens can be isolated, and made to produce large quantities of the antigens they code for. A recombinant vaccine contains these antigens, not the whole organism. Compare with 'modified live vaccine' and 'killed vaccine'.

Reflex ovulator:
Only ovulating after being bred. Cats are reflex ovulators, dogs are not.

Using insulin to maintain the blood glucose level of an animal within the acceptable range.

A term used to describe bacteria which have mutated or changed so they are not affected by an antibiotic that previously killed them or slowed their growth. As more bacteria become resistant to various antibiotics, there are fewer antibiotics which will have an affect on them, thus newer and stronger antibiotics will need to be developed. Inappropriate use of antibiotics (using them too often, for too short a duration or in insufficient dose) may promote the development of resistance.

In pregnancy, a condition in which the foetus dies, and instead of being aborted, the foetal tissue dissolves within the uterus and is absorbed by the mother. The mother will show no outward signs of a foetal resorption.

Respiratory depression:
Decrease in the rate or depth of respiration.

The rear interior surface of the eyeball is called the retina. The retina contains nerve cells referred to as rods and cones. The rods are sensitive to light and the cones to color. The retina receives the light and color and converts them into nerve impulses which go to the brain.

S -

A hardening of tissue, usually the result of chronic inflammation.

Sarcoptic Mange: Skin disease characterized by extreme itching, hair loss, and secondary infection. Usually widespread, but often seen on the belly and inner thighs. Can be treated, but spreads easily.

Sebaceous Adenitis: Inflammation of a sebaceous (oil-producing) gland. In dogs, sebaceous glands are found on the top of the tail near its base, and at the junction of mucous membranes with skin. In cats, these glands are found on the chin, lip margins and the top of the tail.

Seborrhea: Abnormal secretion of the sebaceous glands at the base of hair follicles causing anything from dandruff to greasy scales and crust.

Secondary response:
The faster and greater immune response produced by an animal who has previously encountered that specific antigen. Memory cells are responsible for this more efficient response. Also called 'anamnestic response'.

Second generation:
A description of medications developed from an earlier form of the medication. First generation medications were developed from the original form of the drug; second generation medications are adaptations of first generation drugs; third generation drugs are adaptations of second generation, etc.

Seizure threshold:
The level of stimulation at which a seizure is produced. Raising the seizure threshold makes it less likely a seizure will occur.

Selective Igm Deficiency: A deficiency in the production of the IgM antibody, one of the body’s five classes of immunoglobulins, the proteins produced as antibodies to fight infection and toxins.

Selective serotonin reuptake inhibitors (SSRIs): Medications which slow down the ability of nerve cells to absorb serotonin, a neurotransmitter (chemical that serves as a messenger between nerves). Example: Prozac.

Separation anxiety:
A behavioral condition in which the pet becomes anxious when separated from the owner. Dogs with separation anxiety tend to 'shadow' their owners, greet them exuberantly when they return after being gone, and sometimes vocalize, chew destructively, and urinate or defecate when separated from their owners.

A condition caused by an infection e.g., with bacteria or fungi, or toxins they produce.

Shedding (of organisms):
A term used to describe the release of organisms (bacteria, protozoa, viruses) into the environment from an infected animal. The organisms may be in the stool, urine, respiratory secretions, or vaginal discharges. The 'shedding' animal may or may not be showing symptoms of disease.

Smooth muscle: The type of muscle found in the internal organs such as stomach and intestines (not the heart).

Snow Nose (Winter Nose): Loss of pigmentation on the nose, usually in winter.

Somogyi effect:
A condition in which the blood glucose level increases if too much insulin is given. It occurs when insulin causes the blood glucose level to go so low it stimulates the production of other hormones in the body such as epinephrine which promote the breakdown of glycogen (the chemical compound which the body uses to store glucose) and increases the blood glucose level above normal. It is also called rebound hyperglycaemia or insulin-induced hyperglycaemia.

Sterilization by surgical removal of the ovaries and uterus of a female animal.

: A ringlike band of muscle that constricts a passage or closes an opening, e.g., the anal sphincter constricts to close the anus and relaxes when the animal is passing stool. The urethral sphincter closes the urinary bladder.

Spinal Myelopathy
: Disease of the myelin, or covering (sheath) of the spinal nerves (the spinal cord).

A type of bacteria which is long, slender and assumes a spiral shape. Leptospira species and the bacteria that causes Lyme disease (Borrelia burgdorferi) are spirochetes.

Part of the immune system of an animal. A large tongue-shaped organ in the abdomen containing many lymphocytes. The spleen filters blood and removes damaged cells. It can also manufacture new blood cells if the animal's bone marrow is damaged.

: See Selective serotonin reuptake inhibitors

Staphylococcus (Staph)
: A type of bacteria. Normally found on the skin and upper respiratory tract, but can occasionally cause localized suppurating infection.

Status epilepticus:
A condition in which the animal exhibits one severe (Grand Mal) seizure right after another, with no time to recover in-between.

The narrowing of an organ of passage such as a blood vessel or intestine.

Stress-induced hyperglycemia:
A condition in cats in which the blood glucose level becomes abnormally high when the animal is stressed, e.g., in the veterinarian's office.

A chemical compound, magnesium ammonium phosphate, which is made by the body and can form crystals and stones in the urinary bladder.

Under the skin; often called 'sub Q'.

A partial dislocation of a joint in which the bones become out of alignment but the joint itself is still intact.

A class of antibiotics which contain sulphur. They are bacteriostatic (they stop the growth (reproduction) of bacteria, but do NOT kill them).

Having a litter with more than one father (or breeding).

Supraventricular tachycardia:
A condition in which the heart beats very rapidly because of signals coming from the atria (chambers of the heart that receive the blood) or near the junction of the atria with the ventricles (the chambers of the heart that pump the blood to the body or lungs).

Producing effects similar to the 'flight or fight' response, which means the body is alerted to a danger of some sort and prepares to basically run or fight. Sympathomimetic effects include increased heart rate, sweating, and increased blood pressure.

An agent that enhances the action of another.

Pertaining to a joint made up of bone ends covered with cartilage, ligaments, a cavity filled with synovial fluid (joint fluid) and an outside fibrous capsule, e.g. hip joint, elbow joint.

Systemic: Throughout the body.

Systemic Lupus Erythematosis (SLE): An autoimmune disease in which the immune system sees its own body as foreign matter. Characterized by polyarthritis, hemolytic anemia, skin disease, among many other symptoms.

T -

T cell:
Also called 'T lymphocytes' . The type of lymphocyte which is responsible for cell-mediated immunity. T cells may directly kill a cell or produce chemicals called lymphokines that activate macrophages which will kill the cell. Compare with 'B cell'.

An abnormally high heart rate.

A build-up of bacteria, saliva and food on the teeth which becomes mineralised, forming a hard coating and eventually causing gum disease and tooth loss. See also 'Plaque'.

Third generation:
A description of medications developed from an earlier form of the medication. First generation medications were developed from the original form of the drug; second generation medications are adaptations of first generation drugs; third generation drugs are adaptations of second generation, etc.

Thrombocytopenia: A lower than normal number of platelets in the blood. Platelets, which are actually fragments of specific types of cells, are necessary for blood to clot. Signs of thrombocytopenia include bruising and bleeding from the nose, into the gastrointestinal tract, etc.

Thrombocytopenic Purpura: Is a disease characterized by the formation of platelet clots in the microcirculation (very small vessels). Exact cause is unclear but thought to be due to infections, inherited conditions or immunologic abnormalities. Results in bleeding with a low platelet count, anemia, neurologic symptoms kidney disease and fever.

Thyroid: The largest of the hormone secreting (endocrine) glands located in the neck; it regulates metabolism. 

Thyrotropin releasing hormone: Hormone produced by the hypothalamus that stimulates the pituitary gland to produce thyrotropin (thyroid stimulating hormone-TSH), which in turn stimulates the thyroid gland to produce thyroid hormone. Also called TSH releasing factor or TSH releasing hormone.

A group of specialized cells that together perform a particular function, e.g., muscle tissue, nerve tissue, bone

A measurement of the amount of antibodies in the blood. The test to measure antibodies is usually performed by making a number of dilutions of the blood and then measuring at what dilution there is sufficient antibody to react in the test. For example, a titer of 1:8 (one to eight) means the blood can be diluted to one part blood and seven parts saline and still produce a positive reaction in the test. The higher the titer (1:16 is higher than 1:8), the more antibody is present. (NOTE: The word 'titer' may also be used when discussing the amount of antigen present, e.g., a high titer vaccine has a large number of virus particles.)

To be used on the skin.

The twisting of an organ.

Inflammation of the trachea and bronchi.

Tricyclic antidepressant:
A class of antidepressants which work by decreasing the amount of certain chemical transmitters taken up by specific nerve cells. The tricyclic antidepressants include clomipramine, amitriptyline and fluoxetine (Prozac) and are often used to treat behavioural problems in small animals.

Type I diabetes:
A form of diabetes in which so little insulin is produced that supplemental insulin must be given for the animal to live. Also called insulin dependent diabetes mellitus (IDDM).

Type II diabetes:
A type of diabetes mellitus in which although the blood glucose levels are higher than normal, they are not immediately life-threatening, and the animal can survive without supplemental insulin. Also called non-insulin dependent diabetes mellitus (NIDDM).

U -

A lesion in which the tissue surface is eroded away.

A technique used to get the image of a deep structure within the body by directing ultrasound waves at it and recording the reflections (echoes) from it.

: The area of the body where the umbilical cord is attached; the belly button.

Ununited Anconeal Process (UAP)
: The anconeal process never unites with the ulna, can detach and form a loose body in the joint, called a joint mouse.

A chemical compound which contains uric acid and is made by the body and can form crystals and stones in the urinary bladder. Uric acid is a waste product from the breakdown of certain proteins.

Urinary incontinence:
A phrase used to describe the inability to control urination.

Urinary obstruction:
A blockage in the urinary system, most often occurring in the urethra, the tube that leads from the urinary bladder to the outside of the body.

Urinary retention:
A condition in which the urinary bladder does not rid itself of all urine it contains during the process of urination.

United States Pharmacopeia - a drug regulating agency.

Uveitis: Inflammation of the eye.

Uveodermatologic Syndrome (Vogt-Koyanagi-Harada-like syndrome): Depigmentation of the skin and hair, and of the nose, lips, eyelids, footpads and anus. (In humans this disease is believed to be immune-mediated.)

V -

The act of giving a vaccine. See also 'immunization' since the two words have different meanings and are often confused.

Vaccine failure:
A term often used to describe a condition in which an animal who was vaccinated against a disease still gets the disease. In truth, there is usually nothing wrong with the vaccine, but for some reason the animal's immune system did not adequately react to it.

Inflammation of blood vessels.

Agent which dilates, or increases the diameter of blood vessels.

The chambers of the heart that pump the blood to the body or lungs.

Ventricular arrhythmia:
A heart condition in which the heart beats irregularly and/or at an abnormal rate because of signals coming from the ventricles (chambers of the heart that pump the blood).

Vestibular system:
Portions of the inner ear, nerves and brain which help the body maintain balance.

The smallest form of life, invisible with an ordinary microscope. An infectious unit that enters and uses cells of plants or animals for replication. Some viruses cause disease in animals or plants.

Viscosity: Thickness of a fluid, e.g. molasses is more viscous than water.

Von Willebrand’s Disease: Deficiency of coagulation factor VIII causing prolonged bleeding time.

W -

Warm-blooded: Having a relatively high body temperature that is regulated internally and is independent of the environmental temperature. Mammals and birds are warm-blooded.

Wasting: Loss of muscle mass due to decreased food intake or increased metabolic rate.

Wart: Benign growth caused by a virus.

In dogs, the act of giving birth.

White blood cells (WBCs):
Cells in the blood whose major role is to defend the body against invading organisms such as bacteria, viruses and fungi. There are different types of leukocytes: lymphocytes are part of the immune system; monocytes, eosinophils and neutrophils eat or engulf organisms; basophils contain histamine and are involved in inflammatory reactions.

Window of susceptibility:
A time period in the life of a young animal in which the maternal antibodies are too low to provide protection against a certain disease but too high to allow a vaccine to work and produce immunity.


Zoonotic: A disease which can be transmitted between animals and people.


A more complete Dictionary of Veterinary Terms and Definitions can be found here

E-mail Us to report a broken link!

Main Categories