IMMUNE-MEDIATED HEMOLYTIC ANEMIAS

Immune-mediated hemolytic anemia (IMHA) in dogs has been recognized to cause major morbidity and mortality in dogs for half a century. However, there are no generally accepted guidelines and standard tests to diagnose IMHA in dogs. The assessment of published studies on IMHA disease course, complications, prognosis and therapies are hampered by the varied diagnostic criteria used and dearth of diagnostic studies. Supported by a comparative study of different diagnostic tests for IMHA in dogs by the author’s laboratory (Caviezel et al., 2014), this is personal perspective on the diagnostic approach applied.

Introduction
Hemolytic anemias are characterized by an accelerated erythrocyte destruction which occurs commonly extravascularly and rarely also intravascularly. While IMHA is commonly suspected, when presented with an anemic dog, there are many other causes of anemia and hemolysis. It is critical to search for evidence of hemolysis such as hyperbilirubinuria/-emia, icterus, hemoglobinuria/emia, and regenerative erythroid response. In case of a documented hemolytic anemia, infections (e.g. babesiosis, caval syndrome, malignant histiocytosis and bacterial sepsis), cancer (e.g. malignant histiocytosis, hemangiosarcoma), toxins (onions, zinc) and inherited erythrocyte defects (e.g. PK and PFK deficiency) should be considered. For those diseases, specific diagnostics are available to guide the most specific therapeutic approach. […]