through contamination of the horse's environment. The disease ruptures lymph and damages the horse's blood vessels. It can be fatal. Infected horses may lack energy, be in pain when swallowing and lose their appetite, and develop a fever or cough. Bacteria cultured from the material in the abscesses can be identified for a definitive diagnosis.
Anterior Uveitis
Anterior uveitis in horses is also known as moon blindness or periodic ophthalmia. One cause of anterior uveitis is the action of antibody–antigen complexes on the iris, which causes inflammation of the eye. Once started, the inflammation may cause blindness if not halted. Fortunately, its progression can, in many cases, be slowed or stopped by fast, aggressive, and consistent care. Treatment of immune-mediated anterior uveitis may include whole-body corticosteroids and other drugs that suppress the immune system.
Rheumatoid arthritis
Rheumatoid arthritis is the most well-known autoimmune condition though the mechanisms of disease are not fully understood. Rheumatoid arthritis is triggered by increased production of a molecule called rheumatoid factor. Rheumatoid factor is a molecule that normally helps to regulate immune response. With an increase in production of rheumatoid factor the immune system is hyper-reactive and an autoimmune response against the tissues of the joint occurs. This causes inflammation of the synovial membrane tissue. The breakdown of cells in the synovial membrane causes the release of lysosomal enzymes into the joint fluid. These enzymes begin to breakdown other joint structures. Articular cartilage is particularly vulnerable to damage from digestive enzymes and fibrillation of the articular cartilage is a common symptom of rheumatoid arthritis. As the disease process continues there is erosion of the cartilage and subchondral bone, thickening and fibrosis of the joint capsule, and an increased production of poor-quality synovial fluid. The symptoms of rheumatoid arthritis include heat and swelling of affected joints, pain in affected joints that worsens with palpation or motion, reluctance to move or weight-bear on affected joints, anorexia, weight loss and increased amounts of rheumatoid factor in circulation. Though rheumatoid arthritis most commonly affects joint tissues other synovial structures such as tendon sheaths may also be affected.
Type IV Reactions
Type IV hypersensitivity is also known as cell mediated or ________________ hypersensitivity. This type of reaction occurs when T-helper cells respond to antigens and release toxic and inflammatory substances that can damage tissues. Cell-mediated immune reactions can occur in any organ. Treatment usually involves the use of anti-inflammatory drugs and drugs that suppress the immune system, either alone or in combination. This is often a delayed reaction and involves macrophages.
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