Because of the cost and complexity of treating immune-mediated hemolytic anemia (IMHA) cases, it is important to find accurate prognostic factors. Most information to date has come from retrospective university studies with varying treatment protocols. To better identify prognostic indicators in cases diagnosed with IMHA, a prospective study with a standardized treatment protocol was undertaken. Diagnosis of IMHA was based on standard published criteria and effective rule out of other diseases. For each IMHA case admitted, historical, treatment and clinical data were documented during hospitalization. All discharged cases were followed for at least 3 months.

Of 31 cases originally enrolled in the study, 26 cases were available for analysis in determining chance for discharge and 21 cases were available in determining longer term prognosis. All cases were autoagglutinating. Eighteen cases were discharged (69%), 1 case died, and 7 cases were euthanized in the hospital due to a grave prognosis. Cases that died or were euthanized in the hospital had a significantly higher maximum total bilirubin (Tbili) level than those that were discharged (33.5 versus 4.8, p=0.0004). Between cases that were discharged and those that died or were euthanized, there was no difference in age, packed cell volume, white blood cell count (WBC), platelet count or Tbili on admission, or the presence of hemoglobinuria or hemoglobinemia. The number of transfusions received and hospitalization time were not significantly different between the 2 groups. Only 3 animals had been vaccinated within 2 months; of those, 1 was euthanized and 2 were discharged.

Three-month follow-up information was available for 13 of the 18 cases discharged. Of the 13, 7 cases were still alive at 3 months (7/21, 33%). There was no difference in age, PCV, WBC, platelet count, total bilirubin at admission, number of transfusions received, or hospitalization time between survivors and non-survivors. None of the animals that lived over 3 months had hemoglobinemia or hemoglobinuria during their hospitalization. Maximum Tbili was significantly higher in non-survivors versus survivors (23.7 versus 1.9, p=0.0005). A total bilirubin of greater than 5.16 during hospitalization was associated with an extremely poor prognosis.