Cold hemagglutinin disease in a dog.

Cold hemagglutinin disease, a form of autoimmune hemolytic anemia caused by cold-acting erythrocyte autoantibodies, was diagnosed in a dog. Cold-acting antibodies differ from warm-acting antibodies in several ways, including temperature-dependent reactivity below 32 C. The autoantibody in this case (immunoglobulin M) was in the serum in higher than normal concentrations and was reactive at temperatures approaching freezing. The course of the disease was chronic and was characterized by cyanosis and necrosis of the body extremities. Immunosuppressive therapy with corticosteroids was successful in alleviating the clinical signs and reducing the autoantibody activity in the dog. The cause of this disorder was not determined.