An unusual Heinz body anaemia in a cat

A severe anaemia was diagnosed in a 7-month-old female cat. Most erythrocytes contained unusually large Heinz bodies and showed marked distortion. Six weeks later, the cat had recovered from the anaemia, but the erythrocytes still contained smaller inclusions. By light microscopy, these inclusions did not stain as typical Heinz bodies, but, by electron microscopy, Heinz bodies and autophagocytic vacuoles were identified. It is suggested that this cat had a pre-existing defect in its haemoglobin which made it more susceptible to damage by an unknown oxidizing agent.