Objective—To examine clinical features, laboratory
test results, treatment, and outcome of dogs with
pure red cell aplasia (PRCA) and idiopathic nonregenerative
immune-mediated anemia (NRIMA).
Animals—43 dogs with severe nonregenerative anemia.
Procedure—Medical records of dogs determined to
have PRCA, NRIMA, or ineffective erythropoiesis on
the basis of bone marrow analysis between 1988 and
1999 were reviewed. Criteria for inclusion were ≥ 5-
day history of severe nonregenerative anemia (Hct <
20%; < 60.0 X 103 reticulocytes/µl) with no underlying
diseases. Information was retrieved on signalment,
clinical signs, laboratory test results, treatment, and
Results—Median age of the dogs was 6.5 years.
Spayed females and Labrador Retrievers were significantly
overrepresented. Median Hct was 11% with no
evidence of regeneration (median, 1.5 X 103 reticulocytes/
µl). Direct Coombs' test results were positive in
57% of dogs. Biochemical abnormalities included
hyperferremia and high percentage saturation of
transferrin. Bone marrow findings ranged from PRCA
(5%) to erythroid hyperplasia (55%). Myelofibrosis
was common. Dogs were treated with immunosuppressive
drugs and the response was complete, partial,
and poor in 55, 18, and 27% of the dogs, respectively.
Mortality rate was 28%.
Conclusion and Clinical Relevance—An immunemediated
pathogenesis should be considered in dogs
with severe, nonregenerative anemia, normal WBC
and platelet counts, hyperferremia, mild clinical signs,
and no evidence of underlying disease. Bone marrow
findings range from the rare PRCA to erythroid hyperplasia.
Myelofibrosis is often detected in affected
dogs and may prevent bone marrow aspiration. (J Am
Vet Med Assoc 2000;216:1429–1436)