Ante-mortem and Post-mortem Signs of Anticoagulant Rodenticide Toxicosis in Birds of Prey

Exposure to anticoagulant rodenticides (ARs) in birds of prey is widespread. Interpreting the significance of AR residues in tissue samples recovered from birds in field settings can be challenging for a variety of reasons, including uncertainty regarding the relevance of necropsy findings and the importance of residue levels in the absence of signs of poisoning. A thorough understanding of the pathophysiology of AR toxicosis is useful in evaluating the risks and effects of these toxicants on individual birds and populations. Knowledge of the pathophysiology also aids in recognizing ante-mortem and post-mortem signs of toxicosis. This chapter draws on ante-mortem and post-mortem observations from free-living birds of prey presented to a wildlife hospital to detail signs of poisoning and relates these clinical cases to published literature on AR toxicosis in birds of prey in both field and laboratory settings. Common difficulties in diagnosing AR toxicosis, such as differentiating hemorrhage resulting from poisoning as opposed to traumatic injury, are discussed. Current evidence regarding potential sub-lethal effects of ARs is reviewed. Several case studies that illustrate ante-mortem signs, clinical findings, and post-mortem signs in free-living birds diagnosed with AR toxicosis are presented.