Polycythaemia vera (PV) was diagnosed in a dog by demonstration of an
increased red cell mass in association with normal arterial oxygen sat
uration and the absence of conditions known to be associated with seco
ndary polycythaemia. The dog was treated exclusively by repeated phleb
otomies and replacement of the removed volume by colloid and crystallo
id solutions. It survived for one year and was generally free of signs
.