RESUMEN
Background and Objective: Globally, millions of rodents are used for various researches annually. These animals must be euthanised with a minimum of physical and mental suffering. We describe intramedully injection of air as safe, reliable and humane method of euthanasia for rodents. Design: A prospective study of the effectiveness of intramedullary injection of air was conducted on thirty six Wister rats in the histology laboratory of the Department of Anatomy, College of Health Sciences, Usmanu Danfodiyo University, Sokoto, Nigeria between April to October 2004. Methodology: Thirty six pregnant Wister rats were euthanised by injecting 1ml of air into the medulla through foramen magnum. The time lag between the intramedullary injection of air and achievement of adequate euthanasia was documented for each rat using a stop watch. Results: Out of thirty six rats euthanised through intramedullary injection of air, thirty (83.3%) rats died within 10 seconds after the injection and the remaining 6(16.7%) rats died within 20 seconds after the injection. Conclusion: Intramedullary injection of air is effective, cheap, reliable and humane method of euthanasia in small rodents and requires inexpensive personnel training and is therefore advocated for use in small laboratory animals