Reflections on the tragedy of horse feed contamination by monocrotaline in Brazil

This article reports the largest equids’ mortality from poisonous plants ever recorded worldwide, caused by contamination of a commercial horse feed with Crotalaria sp. seeds. Hundreds of horses died across multiple regions of Brazil, characterizing an epizootic, economic, and social crisis of unprecedented magnitude. We describe the clinical and pathological findings, the epidemiological investigation, and the rapid response achieved through cooperation between veterinary diagnostic laboratories and the Brazilian Ministry of Agriculture and Livestock. Beyond the clinicopathological characterization of pyrrolizidine alkaloid poisoning, we also discuss the associated animal and human suffering and estimate direct and indirect economic losses exceeding US$7 million. Losses included mortality, treatment of affected animals, necropsies, and impacts on sectors linked to the equine industry. Finally, we underscore the importance of differential diagnosis, systematic necropsy procedures, and sample collection for laboratory testing. This feed contamination catastrophe highlights the urgent need for technical managers and quality control professionals to take a leading role in ensuring the safety and traceability of animal feed production.

INDEX TERMS:
Veterinary pathology; neuropathology; forensic pathology; toxic plants; Crotalaria; equines; poisoning