Inclusion Criteria
For inclusion into the study, dogs had to be diagnosed with IMHA based on the presence of regenerative anemia (hematocrit 60,000 reticulocytes/μL), evidence of hemolysis (hyperbilirubinemia, hemoglobinemia, bilirubinuria, or hemoglobinuria), and at least one or more of the following criteria: presence of spontaneous persistent agglutination (that persisted after dilution with saline); at least 2+ spherocytes noted on blood smear; or a positive direct Coombs' test. Spherocytes were reported as 1+ if 1–10 spherocytes were noted in the monolayer of the blood smear per 100 × objective field, 2+ if 11–50 spherocytes were noted per 100 × objective field, and 3+ if 51–150 spherocytes were noted per 100 × objective field.16 Spherocytes were reported as occasional if they were only seen in some 100 × objective fields. At least 10 high-power fields were evaluated for each count. The direct Coombs' test was performed at 37°C with a combined Coombs' reagent containing goat anticanine immunoglobulin G, immunoglobulin M, and complement C3.g Erythrocytes were washed 4 times before the addition of the Coombs' reagent. Dogs were eligible for inclusion in the study only if their owner gave informed consent.