Haematology and Blood Chemistry of the Free-Living Platypus, Ornithorhynchus anatinus (Shaw) (Monotremata: Ornithorhynchidae)

Abstract

Blood was collected under ether anaesthesia from a bill sinus in 45 platypuses, Ornithorhynchus anatinus, caught in southeastern New South Wales. Sexual dimorphisms in haematological and blood chemical values were not found, but there were age-related changes. Juvenile animals had greater erythrocyte counts, lower mean corpuscular volumes, higher potassium, calcium, inorganic phosphate, alkaline phosphatase, cholesterol and albumin, but lower sodium, bicarbonate, urea and protein levels than adults. Reasons for these differences are discussed. Compared to other mammals, the platypus had high haematocrit, erythrocyte count and haemoglobin levels, together with low mean corpuscular volume and high mean corpuscular haemoglobin concentration, which may indicate adaptation to hypoxia. Reticulocytes were not observed. All animals had a small parasite in fewer than 1% of their red cells. Total leukocyte counts were also higher than in other mammals, the mean for adults being 42.84 X 10*9.l-�. The ratio of neutrophils to lymphocytes was approximately 0 5. Metamyelocyte neutrophils were present in low numbers in 14 healthy platypuses. Levels of serum potassium and creatinine were lower, while those of urea, alkaline phosphatase, aspartateaminotransferase and alanineaminotransferase were higher than those usually reported for healthy mammals.