1849: Determinants of Risk in Dogs with Immune Mediated Hemolytic Anemia
Grant Status: Closed
Little is known about the incidence of IMHA in dogs. Although there have been anecdotal suggestions that the incidence is climbing, no objective data exists to substantiate this claim. This study sought to obtain the one-year incidence in a major California metropolitan region and describe the characteristics of the cases seen in private practices. Of 91 eligiblehospitals in the region, 87 hospitals were eligible for participation, and 77 hospitals (88.5%) ultimately agreed to provide information. Forty-eight cases were reported during the year under study; detailed information was provided on 33 confirmed cases (68.8%). The mean first hospital stay as 2.6 days (range: 0-17 days), with a mortality rate of 24%. The one-month mortality was 55%, and the three month mortality was 58%. The most commonly affected breed was Cocker Spaniel with no gender predisposition. The annual rate of confirmed cases of IMHA in this region was 0.012%, or 12 cases per 100,000 dogs seen at private animal hospitals per year. Although this rate is conservative due to hospital nonparticipation (11.5%) and underdiagnosis inevitably occurs, the finding are compatible with the conclusion that IMHA remains a relatively rare disease in the population of dogs seen in private veterinary practice. A retrospective cohort study of dogs seen at the University of California Veterinary Medical Teaching Hospital with IMHA was undertaken to evaluate the effects of presenting clinical signs and treatment options on survival. Seventy-four dogs, confirmed to have IMHA based on patient history and hematologic evaluation, were included in the study. Four factors upon presentation were found to significantly affect the mortality rate among patients. As patient weight increased, mortality from IMHA increased. Survival was inversely related to the square-root of age. A non- regenerative anemia had an adverse affect on patient survival. Mortality was inversely related to the red blood cell count. After accounting for these four variables, no additional prognostic effects of blood urea nitrogen, hyperbilirubinemia, or white blood cell count were observed. Although all patients were treated with corticosteroids, no significant improvements in patient survival were observed following additional single treatment with azathioprine, cyclosporine, or cytoxan; however, there was some evidence of improved patient survival of the combination of azathioprine and cytoxan when combined with corticosteroids. This study demonstrated how patient information at presentation can be employed by veterinarians to provide owners with realistic probabilities of survival.
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