Haematological and Biochemical Characteristics of Nile Crocodiles (Crocodylus niloticus) at the Kainji Lake National Park, Niger State

Baseline haematological and biochemical data for wild and semi-captive Nile crocodiles in Nigeria are scarce, limiting the ability of wildlife veterinarians and conservation managers to assess the health of this protected species. This study characterised selected haematological and serum biochemical parameters in Nile crocodiles managed at the Kainji Lake National Park, Niger State, North Central Nigeria. Thirty crocodiles of varying age classes were physically restrained under chemical immobilisation using tiletamine-zolazepam, and peripheral blood samples were collected from the dorsal tail vein. Complete blood count and serum chemistry analyses were performed at the University of Ilorin Veterinary Laboratory. Mean packed cell volume was 24.1%, with erythrocyte counts and haemoglobin values consistent with published reference ranges for semi-captive crocodilians in tropical regions. Serum uric acid concentrations were markedly higher than mammalian reference values, reflecting the uricotelic nitrogen excretion characteristic of reptiles. Serum aspartate aminotransferase and alkaline phosphatase were within expected ranges, indicating no hepatic compromise. These data represent a useful contribution to the limited literature on clinical biochemistry of wild Nile crocodiles in Nigeria and provide a reference framework for health monitoring within national park conservation programmes. Keywords: Crocodylus niloticus, haematology, serum biochemistry, Kainji, wildlife health.