| Acetylcholine: – One of several neurotransmitters synthesized by the body. Acetylcholine is released when the vagus nerve is stimulated, altering heart muscle contractions as well as the movement of other muscles. |
| Achondroplasia: – A genetic bone growth disorder that results in abnormally short stature and disproportionately short limbs. Achondroplasia is most commonly found in Alaskan Malamute, Scottish deer hound, Norwegian elk hound, Maremmano–Abruzzese shepherd, Great Pyrenees, German shepherd, miniature poodle, Labrador Retriever, beagle, and Cocker Spaniel breeds |
| Addison’s Disease: A disease of the endocrine system that is characterized by weight loss, muscle weakness, fatigue, low blood pressure, and darkening of the skin in exposed and nonexposed areas. Addison’s disease occurs when the adrenal glands do not produce enough of the hormone cortisol. Diagnosing dogs with Addison’s disease may problematic because the characteristic symptoms are common to many other ailments. A properly treated dog, however, can live a normal, active life. |
| Adrenal Gland: – The adrenal glands are part of the endocrine system and are responsible for releasing hormones in the body that control metabolic processes, regulate the balance of salt and water, control the "fight or flight" response, and initiate and control sexual development in childhood and puberty. |
| Allele: – Any one of a series of two or more different genes that occupy the same locus on a specific chromosome that controls intraspecies variance. |
| Allergy: – An immunologic condition that occurs as a result of Type I hypersensitivity reaction following contact with an antigen. |
| Alopecic Syndrome (Color Dilution Alopecia): – Refers to a conditions characterized by a deficiency of, or loss, of the hair. |
| Alter: – Neuter: In male dogs, it refers to the removal of the testicles. Spay: in a female dog, it refers to remove of the uterus and ovaries. |
| Anatomy: An organism’s morphologic structure. |
| Anemia: A blood condition that develops when there are not enough healthy red blood cells in the blood. |
| Antibody: – A protein molecule that is produced by animals in response to foreign matter (antigen). Each antibody binds to the specific antigen that induced its formation. The antibody binds to a particular segment of the antigen called an antigenic determinant, or epitope |
| Antigen: A foreign molecule that induces the formation of antibodies. |
| Arthritis: A condition characterized by inflammation of a joint. |
| Atopy: A term that describes the clinical features of a Type I hypersensitivity reaction |
| Aural Hematoma: A collection of blood in cartilage plate of the ear and the skin that is usually self-inflicted injury as a result of scratching or head shaking. |
| Autoimmune Disease: – A condition where cells or antibodies arise from and attack the host body’s tissues or organs. |
| Autoimmune Hemolytic Anemia (AIHA): A life-threatening autoimmune blood disease that is identified by the presence of antibodies that react to the hosts red blood cells (RBCs). |
| Autosomal: Any chromosome other than a sex chromosome. |
