Granulomatous Reactions
Granulomatous reactions are masses of fibrous connective tissue infiltrated by the white blood cells that form a cell-mediated immune response. They occur in some animals following infection with certain types of bacteria or fungi. Although cell-mediated immune responses effectively fight off these infections in most individuals, in a few animals the immune response is only partially effective and results in a mass at the site of infection.
Contact Hypersensitivity
Contact hypersensitivity results from chemicals reacting with skin proteins. These reactions modify skin proteins in such a way that they are perceived as foreign invaders. The body then produces a cell-mediated immune response against them and causes skin damage. This hypersensitivity usually occurs as a result of contact with sensitizing chemicals, including some medications and insect repellents.
Autoimmune thyroiditis
Autoimmune thyroiditis in horses is similar to Hashimoto thyroiditis in people. The body produces antibodies against enzymes and hormones produced in the tissue of the thyroid gland. The immune response causes morphological changes in the thyroid and leads to hypothyroidism. Symptoms of thyroiditis include goiter, hypothyroidism, lethargy, increase in body weight and exercise intolerance. Symptomatic treatment of this condition includes thyroid hormone replacement therapy.
Other Diseases Affecting Immunity
Any systemic disease has an effect on immune function as the immune system has limited resources to fight disease. Commonly a primary viral infection will leave the body susceptible to secondary bacterial infection, as is often seen with influenza. Though considered a circulatory disorder, lymphadenopathy affects the ability of lymph nodes to filter pathogens out of lymph fluid and may result in the spread or worsening of some conditions.
Equine infectious anemia reduces the body’s immune response
occurs
due to the destruction of infected leukocytes.
Finally, animals affected by
disease show a decreased immune response as a
side effect of the over production of cortisol.
55
Made with FlippingBook Publishing Software