EQ GLOSSARY

allele--- one of the alternative forms of any gene on a chromosome. Each allele represents a different variation of a physical trait and each has one corresponding allele on the chromosome’s paired counterpart. For example, one blue-eye allele will have one corresponding allele that carries either a blue, green or browneye trait. axon--- long, thin extension of a nerve cell that transmits impulses away from the cell body to be picked up by the “receivers” of the next nerve cell. chromosome--- the self-replicating genetic structure of cells containing the cellular DNA that bears in its nucleotide sequence the linear array of genes. Each species has a constant number of chromosomes set in pairs in the nucleus of each body cell; the horse has 64, or 32 pairs. colostrum--- thick, extra-rich milk secreted by the pregnant mare’s mammary glands as they fill, usually before the foal’s birth. Contains globulins and other proteins that provide the foal with temporary immunity against infectious disease. Must be consumed by the foal within a few (maximum 12) hours of birth to confer protection to the foal. corticosteroids--- analogs of the hormone cortisol produced primarily by the adrenal glands; they may be natural or synthetically produced for injection. cortisol (hydrocortisone)---adrenal hormone regulating fat and water metabolism, muscle tone, nerve stimulation and inflammation.

DNA (deoxyribonucleic acid)---large organic molecule that consists of two chains of nucleotides wound around each other; the material of which genes are made. Genes are responsible for the individual inherited characteristics of living organisms.

equine herpesvirus (EHV)---a family of viruses that primarily cause chronic respiratory infections in horses (EHV-1, EHV-4). EHV-1 can also cause abortions in mares and, in rare cases, both EHV-1 and -4 can cause neurological signs, including progressive weakness and incoordination. EHV-3 causes a venereal disease called equine coital exanthema.

equine protozoal myeloencephalitis (EPM) ---inflammation of the brain and spinal cord caused by protozoal infection.

gene--- the fundamental physical and functional unit of heredity; an ordered sequence of nucleotides located in a particular position on a particular chromosome that encodes a specific functional product.

genotype--- total genetic inheritance; all of the genes present in the chromosomes of a horse’s cells, one-half of which came from his father and one-half from his mother.

laminitis--- inflammation of the sensitive plates of soft tissue (laminae) within the horse’s foot caused by physical or physiologic injury. Severe cases of laminitis may result in founder, an internal deformity of the foot. Acute laminitis sets in rapidly and usually responds to appropriate, intensive treatment, while chronic laminitis is a persistent, long-term condition that may be unresponsive to treatment.

lymphangitis (milk leg, Monday morning leg) ---inflammation of lymph vessels and nodes, characterized by hot, painful swellings in and beneath the skin, usually on the legs. necropsy--- examination of an animal’s body after death, normally done to ascertain the cause of death. pituitary pars intermedia dysfunction (PPID, Cushing’s disease)---disease caused when the cortex of the adrenal gland produces excessive amounts of hormones, including cortisol; signs include persistent long hair, thin skin, fragile bones, stupor, weakness and sweating. proud flesh--- excess granulation tissue rising out of and above the edges of a wound, forming a raw, exposed mound that makes further healing delayed or impossible without medication or surgery. serum--- the liquid portion of blood remaining after solid components have been removed by clotting. wobbles (cervical vertebral compressive myelopathy)---incoordination due to malformation of the vertebrae in the neck that causes compression or “pinching” of the spinal cord. In dynamic compression, the vertebrae allow too much motion in the joints, which pinches the cord. In static compression, excess growth of bone and/or cartilage narrows the spinal canal and impinges on the cord.