Vet Terminology starting with A on – from Abdomen to Azotemia


A region of the body between the chest and the pelvis; belly.

The insertion of a needle into the abdominal cavity to remove fluids.

A localized accumulation of pus; usually associated with infection.

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.

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.’

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.

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.

A hormone produced by the adrenal glands that elevates heart and respiration rates; also called ‘epinephrine.’

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.

A solid substance which attracts other molecules to its surface.

Medication formulated to kill adult forms of a parasite.

Needing oxygen to live. See also Anaerobic bacteria.

Aerobic bacteria
Bacteria that require oxygen to survive and grow.

Clumping together.

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

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.’

A hormone secreted by the adrenal gland that stimulates sodium (and therefore water) retention and potassium excretion; important in blood pressure maintenance.

Pertaining to food or the digestive tract.

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

A substance that causes an allergic reaction, e.g., pollen.

A loss of hair or baldness.

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.

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.

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.

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 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.

A hormone which produces male sexual characteristics, e.g., testosterone.

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

Loss of sensation or feeling; induced artificially with drugs to permit painful procedures such as surgery.

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.

A condition in which the pupils of the eyes are not of equal size.

Loss of appetite.

Positioned in front of another body part, or towards the head of the animal. Opposite of posterior.

Medication which kills certain types of intestinal worms; dewormer.

Usually refers to drugs administered to kill or inhibit the growth of bacteria; not effective against viral infections.

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.

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.

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

Stopping the blood clotting process.

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.’

An agent that decreases or stops vomiting.

Drugs administered to kill or inhibit the growth of fungi (plural of fungus).

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.

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

Relieves itching.

A substance used to relieve fever.

A substance which inhibits the growth of bacteria, but does not kill them.

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.

Cough suppressant.

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

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.

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.

A variation from normal heart rhythm.

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.

Inflammation and swelling in the joints; has multiple causes including lameness.

Pertaining to a joint.


Fluid accumulation in the abdomen.

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.

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

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

A coral island consisting of a reef surrounding a lagoon.

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

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.

An abnormal decrease in size of an organ or tissue.

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.

To listen for sounds produced within the body, usually with the aid of a stethoscope.

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.


The presence of increased nitrogenous (containing nitrogen) waste products in the blood as a result of kidney malfunction.