Glossary

Active immunity: Immunity resulting from the development of antibodies in response to the presence of an antigen, as from vaccination or exposure to an infectious disease.

Acute:  a disease with a rapid onset or a short course or both.

Anaphylaxis: exaggerated allergic reaction to a foreign protein resulting from previous exposure to it.

Anemia: a quantitative deficiency of the hemoglobin, often accompanied by a reduced number of red blood cells and causing pallor, weakness, and breathlessness.

Antigen: any substance that can stimulate the production of antibodies and combine specifically with them.

Ataxia: failure of muscular coordination; incoordination of mucular activity.

Attenuated Virus Vaccines:  a vaccine prepared from live microorganisms that have lost their virulence but retained their ability to elicit a protective immune response

Bone Marrow:  The soft blood-forming tissue that fills the cavities of bones and contains fat and immature and mature blood cells, including white blood cells, red blood cells, and platelets. Diseases or drugs that affect the bone marrow can affect the total counts of these cells.

Cell-mediated immunity:  immunity independent of antibody but dependent on the recognition of antigen by T cells and their subsequent destruction of cells bearing the antigen or on the secretion by T cells of lymphokines that enhance the ability of phagocytes to eliminate the antigen.

Cerebellum: The portion of the brain in the back of the head between the cerebrum and the brain stem. The cerebellum controls balance for walking and standing and other complex motor functions.

Cerebellar hypoplasia:  A deficiency of the cell of the cerebellum, the degree and distribution of which is variable.  This results in the animal showing clinical signs consistent with a deficiency of cerebellar function including incoordination.

Chromosomes: A threadlike linear strand of DNA and associated proteins in the nucleus of eukaryotic cells that carries the genes and functions in the transmission of hereditary information.

Conjunctivitis:  inflammation of the conjunctiva (the delicate membrane lining the eyelids and covering parts of the eye.

Coronavirus: any of various RNA-containing spherical viruses of the family Coronaviridae, including several that cause acute respiratory illnesses

Corneal Ulcers:  Damage or compromise to the surface of the cornea of the eye which may be caused by infectious or non-infectious causes.

Disseminated Intravascular Coagulation (DIC):  A hemorrhagic disorder that occurs following the uncontrolled activation of clotting factors and fibrinolytic enzymes throughout small blood vessels, resulting in tissue necrosis and bleeding.

DNA viruses:  A virus in which the genetic material is DNA rather than RNA. The DNA may be either double- or single-stranded. Major groups of double-stranded DNA viruses (class I viruses) include the adenoviruses, the herpes viruses, and the poxviruses. Major groups of single-stranded DNA viruses (class II viruses) include the parvoviruses and coliphages.

Edema:  The swelling of soft tissues as a result of excess water accumulation.

Embryonic Resorption: Early death of the embryo during the fetal period with lysis and complete resorption of all the products of the conception.

Encephalomyelitis:  A general term for inflammation of the brain and spinal cord.

Endemic:  an infection is said to be "endemic" in a population when that infection is maintained in the population without the need for external inputs.

Enteric: Of, relating to, or being within the intestine.

Enteritis: inflammation of the intestine.

Epithelial: any animal tissue that covers a surface, or lines a cavity or the like, and that, in addition, performs any of various secretory, transporting, or regulatory functions.

Epizootic:  An epizootic is the nonhuman equivalent of an epidemic, meaning that large numbers of animals are infected with a disease.

Fetal Mummification:  Death of the fetus resulting in dehydration of the fetus in utero.  The soft tissues are much reduced in volume, the skin is leathey and the tissues are deeply brown-stained. 

Fibrosarcoma: A malignant tumor derived from fibrous connective tissue and characterized by immature proliferating fibroblasts or undifferentiated anaplastic spindle cells.

Fomites:  an inanimate object or material on which disease-producing agents may be conveyed (for example: boots or bedding).

Granulomatous: an inflammatory tumor or growth composed of granulation tissue.  Granulation tissue is tissue formed in ulcers and in early wound healing and repair, composed largely of newly growing capillaries and so called from its irregular surface in open wounds.

Humoral immunity: immunity conferred to an individual through the activity of B cells and their progeny, which produce circulating antibodies in response to the presence of a foreign substance and recognize the substance upon renewed exposure.

Hyperkeratosis: thickening of the horny layer of the skin.

Immune complex: an aggregate of an antigen and its specific antibody.  An antigen is any substance that can stimulate the production of antibodies and combine specifically with them.

Immune System: The body system in humans and other animals that protects the organism by distinguishing foreign tissue and neutralizing potentially pathogenic organisms or substances. The immune system includes organs such as the skin and mucous membranes, which provide an external barrier to infection, cells involved in the immune response, such as lymphocytes, and cell products such as lymphokines.

Immunosuppression: lowering the body's normal immune response to invasion by foreign substances; can be deliberate (as in lowering the immune response to prevent rejection of a transplanted organ) or incidental (as a side effect of radiotherapy or chemotherapy for cancer) or caused by a disease.

Inactivated Modified Live Virus Vaccines:  a vaccine prepared from live microorganisms that have lost their virulence but retained their ability to elicit a protective immune response.

Incubation Period: In medicine, the time from the moment of exposure to an infectious agent until signs and symptoms of the disease appear.

Interferon: any of various proteins, produced by virus-infected cells, that inhibit reproduction of the invading virus and induce resistance to further infection.

Inoculation site:  the site at which the infectious agent breaks through the natural barriers and gains access to infect the body.

Interstitial Pneumonia: Interstitial pneumonia is inflammation of the lung which involves the meshwork of lung tissue (alveolar septa) rather than the air spaces (alveoli).

Intestinal Epithelium:  The cells lining the innermost surface of the gastrointestinal tract.  These aid in the digestion and absorption of ingested feed.  They are rapidly sloughed off and replaced.

Immunization: the process of rendering a subject immune, or of becoming immune.

Latent: (of an infectious agent or disease) remaining in an inactive or hidden phase; dormant.

Lethargy:  Abnormal drowsiness and weakness that may be a result of clinical disease.

Leukemia: any of several cancers of the bone marrow that prevent the normal manufacture of red and white blood cells and platelets, resulting in anemia, increased susceptibility to infection, and impaired blood clotting.

Leukopenia: reduction of a number of white blood cells in the blood.

Live vaccines:  A vaccine prepared from live, usually attenuated microorganisms that elicit a protective immune response.

Lymphoid Tissues:  A part of the body's immune system that helps protect it from bacteria and other foreign entities. Lymphoid tissue is rich in lymphocytes (and accessory cells such as macrophages and reticular cells). The lymphoid tissue includes the lymph nodes, spleen, tonsils and adenoids and the thymus (an organ in the neck that is particularly large during infancy).

Lymphoma: Any of various usually malignant tumors that arise in the lymph nodes or in other lymphoid tissue.

Mutation: a sudden departure from the parent type in one or more heritable characteristics, caused by a change in a gene or a chromosome. 

Naive: having not been exposed to a particular infectious agent.

Opportunistic infections: are infections caused by organisms that usually do not cause disease in a person or animal with a healthy immune system, but can affect people or animals with a poorly functioning or suppressed immune system.

Optic nerve: nerves connecting the eyeballs to the brain.

Oral Epithelium:  the mucosal surface lining the inside of the oral cavity.

Paresis: slight or incomplete paralysis.

Peripheral Nerve:  The peripheral nervous system or PNS, is part of the nervous system, and consists of the nerves and neurons that reside or extend outside the central nervous system (the brain and spinal cord) to serve the limbs and organs, for example. Unlike the central nervous system, however, the PNS is not protected by bone or the blood-brain barrier, leaving it exposed to toxins and mechanical injuries.

Pharynx: the tube or cavity, with its surrounding membrane and muscles, that connects the mouth and nasal passages with the esophagus.

Pneumonia:  Inflammation of one or both lungs with consolidation. Pneumonia is frequently but not always due to infection. The infection may be bacterial, viral, fungal or parasitic. Symptoms may include fever, chills, cough with sputum production, chest pain, and shortness of breath.

Retina:  The retina is the nerve layer that lines the back of the eye, senses light, and creates impulses that travel through the optic nerve to the brain. There is a small area, called the macula, in the retina that contains special light-sensitive cells. The macula allows us to see fine details clearly.

RNA Virus:  A virus in which the genetic material is RNA. The RNA may be either double- or single-stranded and the virus may be contained within a protective coat (Envelope) or be naked.

Retrovirus : Any of a group of RNA viruses whose RNA is used as a template inside a host cell for the formation of DNA by means of the enzyme reverse transcriptase. The DNA thus formed is inserted into the host cell's genome. Most retroviruses can cause cancer. Retroviruses also include HIV.

Septic Shock:  Shock caused by infection.  Shock is a critical condition brought on by a sudden drop in blood flow through the body. There is failure of the circulatory system to maintain adequate blood flow. This sharply curtails the delivery of oxygen and nutrients to vital organs. It also compromises the kidney and so curtails the removal of wastes from the body. Shock can be due to a number of different mechanisms including not enough blood volume (hypovolemic shock) and not enough output of blood by the heart (cardiogenic shock). The signs and symptoms of shock include low blood pressure (hypotension), overbreathing (hyperventilation), a weak rapid pulse, cold clammy grayish-bluish (cyanotic) skin, decreased urine flow (oliguria), and mental changes (a sense of great anxiety and foreboding, confusion and, sometimes, combativeness).

Shed: excretion of an infectious agent from the body of an infected animal.

T-helper cells: a T cell that stimulates B cells to produce antibody against a foreign substance, using lymphokines or direct contact as a signal.

Thymus: a lymphoid organ in the neck, troat or thorax of young animals.

Toxemia:  the presence of toxins in the blood which may result in the spread of the infectious agent throughout the body and shock.

Transmission: the act of passing an infectious disease between animals

Ulcer:  a local defect, or excavation of the surface of an organ or tissue, produced by the sloughing of necrotic inflammatory tissue that can be found in all organs and tissues.

Vesicle:  In dermatology, a vesicle is a small blister, as on the skin. Vesicles also occur on the mucous membranes, such as the buccal mucosa (the lining of the mouth). Vesicles are less than .5 centimeters in diameter.

Virulence:  the relative ability of a microorganism to cause disease; degree of pathogenicity.

Viremia: the presence of virus in the blood, either as free virus or as virus inside of the animal's own cells.