Secondary polycythaemia associated with high plasma erythropoietin concentrations in a dog with a necrotising pyelonephritis

An 11‐year‐old mixed breed dog was presented with anorexia, apathy and intermittent macrohaematuria, absolute polycythaemia (packed cell volume, 80 per cent; red blood cell, 12·2×10 6 /μl) and elevated erythropoietin concentrations. A renal mass was detected by ultrasonography and, following total nephrectomy, diagnosed as necrotising pyelonephritis. After surgery, the haematological parameters and erythropoietin values returned to normal, suggesting that the pyelonephritis was the cause of the polycythaemia. While secondary polycythaemia because of a non‐neoplastic condition of the kidneys occasionally occurs in human beings, it has only extremely rarely been reported in dogs. This is the first case report of a unilateral pyelonephritis causing secondary polycythaemia in a dog.