Ecological Implications of Rodenticide Exposure: First Evidence of Bromadiolone Poisoning in an Indian Leopard ( <scp> <i>Panthera pardus fusca</i> </scp> )

Large carnivores such as Indian leopard (Panthera pardus fusca) play a crucial role in maintaining ecosystem stability. However, they face increasing threats from habitat loss and other anthropogenic pressures. One significant but underreported threat is unintentional or deliberate poisoning, particularly from chemical pesticides. This study reports the first documented case of rodenticide (bromadiolone) poisoning in a large mammalian carnivore in India. In this study, a deceased female leopard (~5 years old) was recovered from the Nilgiris Forest Division, Tamil Nadu, India. Tissues of kidney, liver, and gut contents of the leopard were collected for toxicological investigation. Using high-performance liquid chromatography-mass spectrometry (LC-MS/MS), the samples were screened for 51 pesticides. Bromadiolone, a second-generation anticoagulant rodenticide (SGAR), was detected at concentrations of 802.9 ng/g in kidney, 237.7 ng/g in liver, and 39.3 ng/g in gut. No other pesticides were detected in any of the samples studied. Postmortem examination revealed internal hemorrhaging consistent with bromadiolone-induced coagulopathy, confirming it as the likely cause of death. This study underscores the ecological risk posed by rodenticides through deliberate or secondary poisoning of nontarget wildlife. To prevent such incidents, stricter regulations and greater public awareness regarding the use of anticoagulant rodenticides near forested areas are urgently needed. Additionally, long-term monitoring and research on rodenticide exposure are strongly recommended to guide further conservation actions and safeguard wildlife across the country.