Issue Description Canines are predisposed to developing many different autoimmune conditions. One of the most common autoimmune disorders to affect
dogs is autoimmune hemolytic anemia (AIHA), which is also known as immune-mediated hemolytic anemia (IMHA). AIHA can occur as a primary condition or a secondary
condition related to other autoimmune disorders or malignancies. Autoimmune hemolytic anemia is characterized by the development of autoantibodies that destroy red
blood cells. Other Names Autoimmune Hemolytic Anemia, AIHA, Hemolytic Anemia, IMHA
Causes AIHA in canines occurs as a result of genetic and environmental factors. Dogs who are genetically predisposed develop AIHA when they're exposed to certain
environmental triggers. There have been several reports of canine AIHA caused by bee stings due to the constituents present in bee venom, especially melittin,
histamines, hyaluronidase, hemolysins and phopholipase A. Other causes of AIHA include infectious agents (bacteria, viruses, and parasites), zinc toxicity from
the ingestion of pennies, vaccinations, and certain medications, including antibiotics and analgesics.
Canine autoimmune hemolytic anemia may also
occur as a feature in canines with various neoplasms, including leukemia, lymphoma, myeloma and various tumors. In addition, canine AIHA can occur in dogs with
other autoimmune disorders, especially systemic lupus erythematosus and canine hypothyroidism.
Breeds Affected Females of all breeds, even when they are spayed, have a higher risk for AIHA than males. Although all breeds can be affected, certain breeds have a genetic
predisposition for developing AIHA due to changes in their immune system regulation, a deficiency of pyruvate kinase enzymes, or abnormalities in their red blood
Breeds at higher risk for AIHA include:
Old English Sheepdogs
American Cocker Spaniels
English Springer Spaniels
American Springer Spaniels
West Highland White Terriers
Symptoms Symptoms of canine autoimmune hemolytic anemia vary in severity (from very mild to fatal) depending on the titer of red blood cell autoantibodies and the dog's
general health. Fatality is most likely to occur when there is severe and rapid red blood cell destruction or liver involvement.However, fatality can also result from secondary complications. These complications include the release of coagulants from dying red blood cells. These coagulants, in turn, can cause the formation
of blood clots that lodge in the heart or lungs. In addition, fragments of red blood cells or complexes of red blood cells and autoantibodies can lodge into the
kidneys and interfere with renal function.
Symptoms of canine AIHA include:
Anemia, with low red blood cell count, hemoglobin and/or hematocrit
Pallor of the mucus membranes
Hematuria (presence of blood in the urine)
Spherocytosis seen on blood smear
Positive direct Coombs test
Treatment Treatment consists of corticosteroids such as prednisone and prednisolone as well as other immunosuppressant medications such as cyclophosphamide. Most canines
respond well to a course of treatment lasting several months. In cases of relapse, a longer course of medication may be required. Other therapies for more severe
cases include blood transfusions, splenectomy, and intravenous immunoglobulin therapy.