Present communication describes a clinical case of babesiosis in a 15-month Labrador bitch which at its first presentation showed few piroplasms of Babesia canis, occasional nucleated red blood cells and polychromasia in Giemsa stained blood smear microscopy. Initial values of haemoglobin (Hb) 7 g% and packed cell volume (PCV) 22% further dropped to 3 g% Hb and 12% PCV in subsequent 90 days when the animal was presented in a critical condition with corresponding increase of nucleated RBC (18%), polychromasia and presence of howell jolly bodies. Polymerase chain reaction conducted in the blood revealed Babesia DNA despite negative in blood smear examination. Administration of Diminazene diaceturate, Clindamycin hydrochloride, cortisone and supportive fluid therapy, vitamins and mineral resulted noticeable improvement. Blood examination done after 45 days of treatment showed 9.2 g% Hb and 28% PCV without any red cell abnormality. Based on therapeutic response, performance of blood smear reading for red cell abnormalities characterizing regenerative anaemia as a diagnostic marker for occult/cryptic babesiosis of dog in endemic areas is discussed.
