Primary pure red cell aplasia in dogs: 13 cases (1996-2000).

OBJECTIVES: To examine clinical features, laboratory test results, treatment, and outcome of dogs with pure red cell aplasia (PRCA).

DESIGN: Retrospective study.

ANIMALS: 13 dogs with severe nonregenerative anemia and bone marrow erythroid aplasia.

PROCEDURES: Medical records of dogs determined to have PRCA on the basis of results of blood and bone marrow analysis between 1996 and 2000 were reviewed. Criteria for inclusion in the study were severe nonregenerative anemia (Hct < 20%; reticulocyte count < 1.0%), selective erythroid aplasia in bone marrow, and lack of underlying diseases that may have caused the anemia.

RESULTS: Median age of dogs was 6.5 years. Females were significantly overrepresented. Median Hct was 10%, and median reticulocyte count was 0.1%. Direct Coombs' test results were negative for all dogs tested, and spherocytosis was evident in 2 dogs. All dogs were treated with prednisolone, and 2 dogs were treated with prednisolone and cyclophosphamide. Responses to treatment were complete, partial, and poor in 10, 1, and 2 dogs, respectively. Median time required to achieve an increase of 5% or more in Hct was 38 days, and median time to complete remission was 118 days. Of 10 dogs for which follow-up information was available, only 1 required long-term immunosuppressive treatment.

CONCLUSIONS AND CLINICAL RELEVANCE: Dogs with PRCA appear to respond readily to treatment with immunosuppressive drugs; however, hematologic responses may not be observed for weeks to months after initiation of treatment.