Objective—To determine clinical and clinicopathologic
features of a chronic intermittent severe hemolytic
anemia characterized by erythrocyte osmotic fragility
in Abyssinian and Somali cats.
Animals—13 Abyssinian and 5 Somali cats.
Procedures—History, pedigree information, and
results of routine laboratory tests, special erythrocyte
studies, and histologic evaluation of splenic and
hepatic specimens were analyzed.
Results—Age at which clinical signs of anemia were
first apparent ranged from 6 months to 5 years. Ten
cats had splenomegaly. Most often, the PCV was
between 15 and 25%, but it was as low as 5% at some
times. The anemia was characterized by macrocytosis
and mild to moderate reticulocytosis, but no poikilocytosis.
Hyperglobulinemia, lymphocytosis, mild hyperbilirubinemia,
and high hepatic enzyme activities were
common findings. Results of Coombs tests and tests
for infectious diseases were negative. The erythrocytic
osmotic fragility was high in affected cats (mean
osmotic fragility, 0.66 to 0.78%), compared with
healthy cats (0.48 to 0.58). No specific membrane protein
abnormality, erythrocyte enzyme deficiency, or
hemoglobinopathy was identified. Histologic evaluation
of splenic and hepatic specimens revealed
extramedullary hematopoiesis and hemosiderosis.
Four of the 5 Somali cats were closely related.
Conclusions and Clinical Relevance—On the basis of
results of pedigree analyses, the apparent breed
predilection, and the exclusion of other known causes of
anemia in cats, we believe that the hemolytic anemia in
these cats was likely a result of a novel hereditary erythrocyte
defect. A genetic predisposition to immunemediated
destruction of erythrocytes could not be ruled
out. (J Am Vet Med Assoc 2000;217:1483–1491)