Transient erythrocytosis (Primary polycythaemia) in a dog

The clinical findings in a dog with transient erythrocytosis (primary polycythaemia) are described. The dog was initially presented for neurological signs induced by exercise. The diagnosis was based on PCV (74%), clinically normal hydration, normal arterial blood gas determination, and exclusion of reported causes of secondary polycythaemia. Serum erythropoietin concentration was normal. Phlebotomy decreased the PCV to 45%. During the next 18 months, the PCV remained in the normal range without further treatment, and there was no recurrence of clinical signs.