combined immune deficiency syndrome (disease)

An inherited defect of immunity, including lack of immunoglobulin synthesis, absence of cell-mediated immunity, thymic hypoplasia and a marked reduction in the number of thymic, splenic and blood lymphocytes, which occurs in foals of Arab breeding. It is inherited as an autosomal recessive trait. Clinically the foal is normal at birth but as the passive antibody acquired from the mare declines the foal succumbs to a succession of respiratory infections characterized by nasal discharge, cough, dyspnea and noisy breath sounds. The disease is inexorably progressive and fatal. Called also CID and PSCID for primary severe CID.