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Dictionary of Veterinary Terms A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z   A   AAFCO Association of American Feed Control Officials; an organization which sets standards for pet food ingredients and minimum daily requirements.   Abdomen A region of the body between the chest and the pelvis; belly.   Abdominocentesis The insertion of a needle into the abdominal cavity to remove fluids.   Abscess A localized accumulation of pus; usually associated with infection.   ACE inhibitor 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.   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.   Activated charcoal Charcoal which has been treated to increase its adsorptive power (ability to have chemicals adhere to it); used to treat various forms of poisoning.    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 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) in Dogs.   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.   Adrenaline A hormone produced by the adrenal glands that elevates heart and respiration rates; also called 'epinephrine.'   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 A solid substance which attracts other molecules to its surface.   Adulticide Medication formulated to kill adult forms of a parasite.   Aerobic Needing oxygen to live. See also Anaerobic bacteria.   Aerobic bacteria Bacteria that require oxygen to survive and grow.   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.   Albumin A protein in the blood responsible for the maintenance of osmotic (water) pressure in the blood; also binds (attaches) to large molecules in the blood and serves to transport them; produced by the liver; also called 'serum albumin.'   Aldosterone A hormone secreted by the adrenal gland that stimulates sodium (and therefore water) retention and potassium excretion; important in blood pressure maintenance.   Alimentary Pertaining to food or the digestive tract.   Alkaline A substance with very few hydrogen ions, and a pH over 7. Lye is strongly alkaline.   Allergen A substance that causes an allergic reaction, e.g., pollen.   Alopecia A loss of hair or baldness.   Alveoli The tiny microscopic areas of the lung where the actual exchange of oxygen and carbon dioxide into and out of the blood occurs. Also called alveolus and alveolar sacs.   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 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. See article: Anaphylaxis in Dogs and Cats. May also be referred to as anaphylactic shock or anaphylactoid reaction.   Androgen A hormone which produces male sexual characteristics, e.g., testosterone.   Anemia A condition in which the number of red blood cells present in the blood is lower than normal.   Anesthesia Loss of sensation or feeling; induced artificially with drugs to permit painful procedures such as surgery.   Angiography The x-ray of vessels after injecting a contrasting fluid.   Angiotensin-converting-enzyme inhibitor (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.   Anisocoria A condition in which the pupils of the eyes are not of equal size.    Anorexia Loss of appetite.   Anterior Positioned in front of another body part, or towards the head of the animal. Opposite of posterior.   Anthelmintic Medication which kills certain types of intestinal worms; dewormer.   Antibiotics Usually refers to drugs administered to kill or inhibit the growth of bacteria; not effective against viral infections.   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.   Antidiuretic hormone A hormone produced by the pituitary gland that reduces the production of urine in the kidneys and therefore prevents water loss; also called 'vasopressin.'   Antiemetic An agent that decreases or stops vomiting.   Antifungal Drugs administered to kill or inhibit the growth of fungi (plural of fungus).   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.   Antipyretic A substance used to relieve fever.   Antiseptic A substance which inhibits the growth of bacteria, but does not 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.   Anus A muscular opening at the end of the digestive tract where fecal waste is expelled.   Aplastic anemia A serious condition in which red blood cells, white blood cells, and platelets are not produced in sufficient quantity.   Aquaculture The (usually commercial) captive raising of fish, corals, and other aquatic life for aquariums, food, and scientific purposes.   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.   Arteries Thick walled vessels that carry blood away from the heart to the lungs and body tissues; the pulmonary arteries carry deoxygenated blood to the lungs, but all other arteries carry oxygenated blood.   Arthritis Inflammation and swelling in the joints; has multiple causes including lameness.   Articular Pertaining to a joint.   Ascarid Roundworm. See article: Roundworms in Dogs and Cats.   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. Also the breathing in of a fluid or foreign substances.   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.   Atoll A coral island consisting of a reef surrounding a lagoon.   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.   Atrial fibrillation 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.   Atrial 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.   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.   Atrophy An abnormal decrease in size of an organ or tissue.   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.   Auscultate To listen for sounds produced within the body, usually with the aid of a stethoscope.   Autoimmune A condition in which 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 hemolytic anemia, the body destroys its own red blood cells. In rheumatoid arthritis it attacks the cells in the joints.   Axilla Armpit.   Azotemia The presence of increased nitrogenous (containing nitrogen) waste products in the blood as a result of kidney malfunction.   B   B cell Also called 'B lymphocyte.' The type of lymphocyte which produces antibody. Compare with 'T cells.'   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.   Bacterium Microscopic organisms that lack nuclei and other organelles; pathogenic species cause disease, while nonpathogenic species are harmless.   Barium Study A procedure in which a pet is given barium to swallow or as an enema, followed by x-ray exams to locate disorders of the esophagus, stomach or intestine.   Benign A mild illness or non-malignant form of a tumor. Benign tumors usually have well defined edges and tend to grow slowly.   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.   Bilateral On both sides.   Bile A liquid produced by the liver, stored in the gall bladder, and dispensed into the small intestine as needed; aids in the digestion and absorption of fats.   Bile acids Certain compounds produced by the liver, bound to amino acids, and excreted in the bile to aid in the digestion of fats.   Bilirubin An orange-yellow pigment in bile that is a product of red blood cell breakdown; it is normally excreted with the urine or feces, and a buildup in the body can cause jaundice.   Biopsy The surgical removal of a small amount of abnormal tissue, usually of tumors, for diagnosis.   Bitch A female dog.   Bladder A sac that receives and holds a liquid until it is excreted, e.g., urinary bladder, gall bladder; in fish, the swim bladder holds air.   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 gases Gases, such as oxygen or carbon dioxide, that are in the blood.    Blood glucose 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 A soft tissue composed of blood vessels and connective tissues found at the center of bones; the primary function is blood cell production.   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.   Bronchi The plural of bronchus, the large air passages of the lungs.   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.   Bronchoscope A tool designed to facilitate inspection of the trachea and bronchi; used in both diagnostic and therapeutic procedures.   Bronchoscopy The internal inspection of the trachea and bronchi using a bronchoscope.   Bronchospasm A 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.   Calculus (Plural calculi) Abnormal stone-like structure(s) usually composed of mineral salts, e.g., a bladder calculus is the same thing as a bladder stone.   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 malignant tumor.   Candida A certain genus of yeast which can cause disease in humans and animals; an infection with Candida is called candidiasis.   Canine Pertaining to dogs.   Carapace The upper shell of a turtle or tortoise.   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.   Carcinoma A malignant cancer that arises from the epithelial tissues of the body such as the skin, intestinal tract, and bladder.   Cardiac Related to the heart.   Cardiomyopathy Diseases of the heart muscle; does not include diseases of the valves of the heart or congenital defects.   Cardiopulmonary Relating to the heart and lungs.    Cardiovascular Related to the heart and blood vessels.   Carnivore An animal whose natural diet includes meat.   Carpus The wrist (front leg) of dogs and cats.    Carrier An 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.   Castration The removal of the sex organs making the animal incapable of reproduction; the correct use of the word can be used to describe both male and female animals, but it is commonly used to describe only males.   Cataract A cloudiness of the lens of the eye, reducing vision and giving the eye a pearly appearance.   Caudal A directional term used to refer to an area more toward the cauda, or tail region; opposite of cranial.   Caval syndrome Disease caused by large numbers of worms in the right side of the heart and vena cava, which results in blood circulation problems in the liver leading to the breakdown of red blood cells, anemia, weakness, and collapse.   Cecum A blind sac that opens into the colon; found in 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.'   Centrifuge A machine that rapidly spins liquid samples and separates out the particles by their density.   Cerebellum A portion of the brain, located on the brainstem, that controls coordination.   Cerebral Relating to the part of the brain known as the cerebrum.    Cerebrum The largest portion of the brain that performs all higher cognitive functions and is situated in the front part of the cranial cavity.   Chelation Binding of a substance to a metal, thus helping the body to remove it.   Chemotherapy Treatment of a disease with chemical agents (drugs); the term is most commonly used to describe the treatment of cancer with medication.   Choana (Plural choanae) An opening between the nasal cavity and oropharynx (mouth) in birds and reptiles.   Cholangiohepatitis Inflammation of the gall bladder, bile ducts, and liver   Cholangitis Inflammation of a bile duct; see cholecystitis.   Cholecystitis Inflammation of the gallbladder; see cholangitis.   Chondroitin Decreases the activity of enzymes which break down cartilage in a joint.    Chondroprotective agent A nutritional supplement that protects cartilage.   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.   Cirrhosis A liver disease caused by the replacement of damaged cells with connective tissue; severe scarring can eventually cause liver failure.   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.   Clinical study A planned examination of the effectiveness of a new drug or treatment for a disease as compared to a control group not receiving the treatment; also called a clinical trial.   Cloaca A common tube-like structure through which feces, urine, and reproductive fluids/eggs pass in birds, turtles, and other lower vertebrates.   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.    Clutch The uninterrupted series of eggs laid by a hen, usually 2-6 depending on the bird species.   CNS Central nervous system. Includes the brain, spinal cord, and the nerves leading from them.   Coagulation The process of clotting.   Coagulopathy A condition affecting the blood's ability to form a clot.    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 in Dogs and Cats.   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.   Cold-blooded Having a body temperature that is not regulated internally, but varies with the environmental temperature. Turtles, lizards, and snakes are cold-blooded.   Colitis An infection or inflammation of the colon.   Colon A part of the digestive tract, specifically the part of large intestine that extends from the cecum to the rectum.   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.   Complete blood count A count of the total number of cells in a given amount of blood, including the red and white blood cells; often referred to as a 'CBC,' it is one of the most common tests done to check for abnormalities of the blood.   Computerized tomography scan (CT scan) A radiological imaging procedure that uses x-ray pictures to produce "slices" through a patient's body; also called a computerized axial tomography (CAT).   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.   Conjunctiva A thin membrane which lines the inside of the eyelids and covers part of the eyeball.    Conjunctivitis An inflammation of the lining of the eyelids; may cause pain, redness, itching, and a discharge.   Constipation A condition in which the movement of food through the digestive system is longer than normal; often results in hard, dry stool.   Contrast agents A substance given orally or injected into a patient that makes the affected tissue easier to identify on an x-ray.   Contusion An injury to underlying tissues without breaking the skin; a bruise.   Coprophagia Eating dung or fecal matter; normal behavior in some animals, such as rabbits.   Core vaccine Vaccine which should be given to all animals of certain species, example, parvovirus vaccine in dogs or panleukopenia in cats (see noncore vaccine).   Cornea The clear part of the front of the eye which allows light in.    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.   Cortisol The main glucocorticoid; a hormone naturally produced by the adrenal gland; it is synthesized commercially as hydrocortisone and is used to reduce inflammation.   Coumestan Estrogen-like substance produced by certain plants such as alfalfa; types of phytoestrogen.   Coumestral Estrogen-like substances produced by certain plants such as alfalfa; types of phytoestrogen.   Cranial A directional term used to refer to the area near the cranium, or head region; opposite of caudal.   Crop An organ between the esophagus and stomach of many domestic birds, which serves as a temporary food storage organ.   Crust Area of dried fluid or cells on the skin. The fluid may have been blood, serum, pus, or medication.   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.   Cushings disease Cushing's disease is also known as hyperadrenocorticism. It is a disease that results from an increase in corticosteroid secretion from the adrenal gland. See article: Cushing's Disease (Hyperadrenocorticism) in Dogs.    Cutaneous Relating to the skin.    Cyanosis Bluish or grayish color to the skin and gums which occurs when the animal has insufficient oxygen.   Cyst An abnormal sac-like structure that is lined with cells which produce a liquid or thick material.   Cystitis Inflammation of the urinary bladder.   Cytokines Compounds produced by certain cells, which act as messengers to control the action of lymphocytes and other cells in an immune response.   Cytology The study of cells; often refers to the microscopic examination of a sample taken from the skin or lesion to look for the cause of a condition.   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.   Decontaminate Remove injurious material.    Defecation The elimination of feces from the rectum.   Dehydration A condition in which the body loses more water than it takes in.   Dermal Relating to the skin.    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.   Dextrose A commonly used name for glucose (sugar) solutions given intravenously to treat fluid or nutrient loss.   Diabetes mellitus 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.   Diagnostic tests Procedures run to find the cause of disease or discomfort; tests used to make a diagnosis.   Dialysis A process which involves removing waste products from the body.    Diarrhea A condition in which the movement of food through the digestive system is faster than normal; often results in the frequent passing of abnormally loose or watery stool.   Diestrus The stage of the estrus cycle which occurs after the animal goes out of heat (also called Diestrous).   Dietary indiscretion Eating what one should not. 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.   Digestive system The organ system including the mouth, teeth, tongue, esophagus, stomach, intestines, and various glands that functions to ingest, digest, and absorb nutrients.   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.   Dinoflagellate Single-celled algae, mainly marine and often with a cellulose shell; some species may be luminescent, and some cause the red tides that are extremely toxic to marine life.    Disinfection The act of using chemicals or heat to kill germs.   Distemper Canine distemper is a viral disease that causes 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.   Diuresis Increase in urine production.    Diuretic Agent which increases the secretion of urine, ridding the body of excess fluid.   Diurnal Active during the day, opposite of nocturnal, which means active during the night.   DNA Deoxyribonucleic acid, the chemical compound that occurs in cells and is the basic structure for genes.   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.   Dry Eye 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.   Duodenum The first portion of the small intestine extending from the stomach to the jejunum; most chemical digestion and absorption of nutrients occurs here.   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.   Dysecdysis Abnormal shedding of the skin in reptiles.    Dysphagia Difficulty swallowing.   Dysplasia An abnormal tissue development, common in the bones of the canine.   Dyspnea Shortness of breath.   Dystocia Difficult birth.   Dystrophic Disorder caused by incorrect nutrition.   Dysuria Difficult or painful urination.   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.   Ecdysis Shedding of the external layers of the skin in reptiles.    ECG A printout of an analysis of the electrical activity in the heart.   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).   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.   EKG A printout of an analysis of the electrical activity in the heart.   Electrocardiogram A printout of an analysis of the electrical activity in the heart.   Electrocautery An instrument with a very hot tip, heated by electricity, is applied to a tissue. Electrocautery may be used to make an incision, remove a mass, or to stop bleeding.   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.   Electroretinography The recording of electrical changes in the retina of the eye in response to stimulation by light.   Elizabethan collar A large, plastic, cone-shaped collar used on cats, dogs, and birds to prevent them from licking or biting at skin, wound dressings, or casts.   Emaciation The severe loss of body weight; body weight is generally less than 50% of that in a normal animal.   Emesis Vomiting.   Encephalitis Inflammation of the brain; often caused by a virus.   Encephalopathy Any degenerative disease of the brain. Causes include liver disease resulting in the buildup of toxic by-products of metabolism, heavy metal (e.g., lead) poisoning, and loss of blood supply.   Endocrine Pertaining to the secretion of hormones. The endocrine system consists of various glands which produce hormones.   Endoscope A long flexible instrument which can be passed into the body to view various structures through the use of fiber optics.   Endotracheal tube This tube is placed into the animal's trachea (windpipe) to allow the oxygen and gases to be breathed into the lungs.    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.   Envenomation The act of injecting a poisonous material (venom).    Enzyme Enzymes are special proteins produced by cells which cause chemical changes in other substances, but which are not themselves changed in the process.   Eosinophil A type of white blood cell that commonly increases in numbers as a response to parasites and allergies.   Eosinophilia A condition in which there are more than the usual number of eosinophils in the circulating blood.   EPA Environmental Protection Agency. The agency of the federal government which licenses pesticides and herbicides.   Epidermis The top layer of the skin.   Epiphora An overflow of tears upon the cheeks due to a blockage or narrowing of the tear ducts.   Epistaxis Bleeding from the nose.   Erosion A shallow defect in the skin. When healed, it will not cause a scar.   Erythema Redness of the skin caused by blood clogging in small blood vessels.   Erythrocyte Red blood cell; contains hemoglobin, which carries oxygen to the tissues.   Esophageal reflux A condition in which stomach contents move backward into the esophagus, i.e., heartburn.   Esophagus The muscular tube for the passage of food from the mouth to the stomach.   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.   Exophthalmos The abnormal outward protrusion (bulging) of the eye.   Exotic An animal not native to the geographical area where it is living.   Extensor rigidity A condition in which muscles contract and tend to straighten the limb, prevent it from relaxing.    Extracranial Originating external to the cranial (brain) cavity.   Extrahepatic Outside of the liver.   F   False negative test result The result of a diagnostic test is negative; but the animal actually does have the condition tested for.    False positive test result The result of a diagnostic test is positive; but the animal actually does not have the condition tested for.    FDA Food and Drug Administration. The federal agency which approves drugs and medications for use in animals and people.   Feces Body wastes excreted through the anus from the large intestine; also called stool.   Feline Pertaining to cats.   Fetal Pertaining to an unborn animal, or fetus.   Fetus The developing young in the uterus before birth.   Fine needle aspirate Suction is applied to a hollow needle which has been inserted into tissue and a core of the tissue is withdrawn to culture and/or examine microscopically.   First generation 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.   Flatulence 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.   Fluoroscopy An x-ray procedure in which x-rays are transmitted through the body onto a fluorescent screen; beneficial in that movement of joints or organ systems can be observed (e.g., the movement of material through the esophagus, stomach, and intestines).   FLUTD Feline lower urinary tract disease; a condition in cats characterized by blood in the urine, urination outside of the litter box, and straining to urinate. The name for this condition was previously called feline urological syndrome (FUS).   Follicle The group of cells in the skin in which a hair or feather develops.   Foreign body Any abnormal substance within the body. Examples include wood slivers, ingested cloth or balls, glass in the feet, etc.   Fracture A break in the bone; generally caused by trauma, twisting, or weakened bone structure due to disease.   Free radical Atom which carries an unpaired electron; free radicals can potentially injure cells and may be responsible for numerous age-related diseases.   Fungicide A drug that kills fungi.   FUS Feline urological syndrome; a condition in cats characterized by blood in the urine, urination outside of the litter box, and straining to urinate. The name for this condition is now called feline lower urinary tract disease (FLUTD).   G   Gait The manner or style of movement; often used to assess horses or dogs for lameness.   Gastric Relating to the stomach.    Gastric lavage To flush out the stomach.    Gastritis Inflammation of the stomach.   Gastrointestinal Also known as GI. Pertaining to the stomach and intestines. The term 'digestive system' includes the mouth, gastrointestinal tract, anus, pancreas, and liver.   Germs Any microscopic organism that can potentially cause disease; includes viruses, bacteria, and fungi.   Gestation Pregnancy.   Gingival Relating to the gums.   Gingivitis Inflammation of the gums.    Glaucoma Increased pressure within the eye caused by an accumulation of fluids; can lead to blindness if left untreated.   Glipizide An oral medication that can be used to control blood glucose levels in some diabetic cats who still have some insulin production.   Glomerulus This literally means a small cluster; commonly used to refer to the renal glomerulus, the area of blood filtering in the kidney.   Glucocorticoid 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.   Glucocorticosteroid 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.   Glucosamine One of the building blocks the body uses to make new cartilage.   Glucosuria Glucose in the urine. (Also called glycosuria.)   Glycogen A storage form of glucose in the body.   Glycosaminoglycans 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.   Gram 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.   Granuloma 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 its effects, which include the production of stomach acid.   Half-life The time required for the level of a substance in the body (e.g., a drug or toxin) to be reduced by half.    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).   Heartworm A species of parasitic worm (Dirofilaria immitis) 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 A condition in which the red blood cells are destroyed and this results in anemia. The specific type of anemia is called 'Heinz body anemia' because the red cells develop an abnormality called a 'Heinz body' which can be seen under the microscope. This anemia can occur as a reaction to certain medications and also in cats who eat onions.   Hemangiosarcoma A malignant tumor of the blood vessels, usually occurring in the skin, liver, spleen, right atrium of the heart, and muscle; also called angiosarcoma.   Hematocrit PCV (Packed Cell Volume), 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.   Hematology The study of blood, its physiology and pathology.   Hematoma A mass of blood within the tissues. Generally, the result of trauma to the blood vessels or abnormal blood clotting.   Hematuria A condition of blood in the urine.   Hemodialysis A process used to remove waste products from the blood.    Hemoglobin A protein inside of red blood cells, responsible for the binding and transport of oxygen to the body tissues (Hb).   Hemolytic Causing the red blood cells to break open.   Hemoptysis Blood in the sputum.   Hemorrhage To bleed excessively; may be the result of injury or blood clotting abnormalities.   Hemostat A small surgical instrument used to clamp blood vessels to prevent bleeding.   Hepatic Pertaining to the liver.   Hepatic fibrosis Scarring of the liver   Hepatitis An inflammation or infection of the liver.   Hepatomegaly Enlargement of the liver.   Herbivore Animal that eats primarily plants and vegetation.   Hernia The protrusion of an organ through an abnormal opening.   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 its effects, which include the production of stomach acid.   Hob A male ferret.   Hormone Chemical substance produced by one part of the body which serves as a messenger to or regulator of the processes of another part of the body.   Host 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.'   Hybrid 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 A condition of fluid accumulation in the ventricles (spaces) of the brain; the swelling generally creates pressure on the brain tissues and can cause severe damage if not treated properly.   Hyper A prefix meaning abnormally high or excessive.   Hypercalcemia An increased level of calcium in the blood.   Hyperesthesia Abnormal sensitivity to touch, pain, or other sensory stimuli.    Hyperglycemia Higher than normal blood glucose level.   Hyperkalemia Increased level of potassium in the blood.   Hyperphosphatemia Elevated blood phosphate levels.   Hyperpigmentation An increased dark color in the skin caused by the pigment 'melanin.'   Hyperplasia An increase of the number of cells within an organ.   Hyperplastic 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.   Hyperreactive Producing an exaggerated, or greater than normal response to a stimulus.   Hypersensitive A type of allergic condit