Caprine arthritis and encephalitis virus infection has emerged since the late 1980s as a major cause of disease, primarily in European breeds of dairy goats under intensive management. All breeds of goats are susceptible to this retrovirus, and prevalence of infection is related to exposure to virus.
Two distinct forms of locomotor problems arise. A neurologic form of the disease occurs in young goats, usually 2–4 months old but as old as 1 year. It is characterized by a progressive paresis with incoordination leading to paralysis, usually involving the hind limbs and later the forelimbs. In adult goats > 1 year old, the virus infection manifests as a chronic, progressive arthritis involving one or more joints and usually involving the carpal joints. The initial sign is usually swelling of the affected joints, followed by progressive degeneration of articular and periarticular tissues with calcification, leading to decreased range of motion, ankylosis, and loss of mobility. Affected goats will often eat while kneeling on the forelimbs.