PRIMARY IMMUNODEFICIENCIES IN HORSES

Abstract

Immunodeficiencies are rare in horses and can be fatal. Failure to one or more aspects of the immune system can cause recurrent infections and fever; in addition, infections by opportunistic organisms are an important clinical feature of this condition. The primary immunodeficiencies may be caused by genetic defects, and the secondary immunodeficiencies can be due to viral, metabolic, endocrine or nutritional disorders. Among the primary immunodeficiencies, the most common involve the humoral system and affect antibody production; cellular deficiencies are more difficult to diagnose and, therefore, less understood. Primary immunodeficiencies usually manifest in early age, when the protective maternal antibodies are reduced around 2 to 3 months of age. Furthermore, in the foal, the immune system develops gradually with age and exposure to environmental organisms; therefore, in this period, there is a natural susceptibility to infections until immunocompetence and memory are achieved. This paper describes the conditions of primary immunodeficiencies reported in horses.