Biliary parascarosis in a foal

Migration of Ascaris lumbricoides through the papilla of Vater in humans, and entry into the biliary tree, is well-recognised. Ascaris suum and Toxocara vitulorum have been recovered from the liver of swine and buffalo. We necropsied a Persian Kurdish filly at age 6 months, weighing ∼100 kg. Death evidently was caused by oleander (Nerium oleander) intoxication. An 8-cm adult male Parascaris was found at the lobar-left hepatic bile duct junction. We suggest that the nematode entered anteriorly into the hepatic tree, via the duodenum, major duodenal papilla, bile duct, left hepatic duct and finally the lobar duct. Considering the brief 4-h elapsed time between death and necropsy, and the 18-cm distance from the major duodenal papilla to the location of the parasite, we conclude that entry into the biliary tree likely occurred ante-mortem. We advise consideration of Parascaris infection in differential diagnosis of equine hepatic and pancreatic dysfunction.