Mortality supposedly due to intoxication by pyrrolizidine alkaloids from Heliotropium indicum in a horse population in Costa Rica: A case report

This article describes a case of massive mortality among horses which was p robably due to intoxication by pyrrolizidine alkaloids from Heliotropium in dicum. Over 4 years more than 75% of a population of about 110 horses on a farm in Costa Rica died after showing nervous neurological symptoms. Two cl inical manifestations were encountered, an acute and a chronic one, both wi th a fatal outcome. Pathological findings in 2 horses coincided with those reported in the literature for intoxication by pyrrolizidine alkaloids and were not specific for VEE. However Venezuelan equine encephalitis (VEE) was the main differential diagnosis and could not completely be excluded becau se this disease was endemic in the region and VEE titres were found to be h igh. Taxonomic and toxicological investigations implicated Heliotropium ind icum as the most probable principal cause of the intoxication.