Age-related changes in the haematology of young koalas (Phascolarctos cinereus) up to one year old

Haematology and biochemistry of captive pouch young and back young koalas from 165 days to one year old were studied. Distinct changes with age were observed. Packed cell volume, haemoglobin, erythrocyte count, MCV and total plasma protein where lowest in the youngest animals less than 180 days old. Reticulocytes were highest in this age group. Haematological values differed from those of adult animals. Lymphocytosis occurred, especially between 210–330 days of age. Intense erythropoiesis was indicated by reticulocytosis and the presence of erythrocyte granular inclusions, anisocytosis and poikilocytosis on blood films, particularly up to 330 days of age. Microcytosis present on blood films throughout the study period could not be explained by iron deficiency.