Toxicological effects of aflatoxins in horses

Aflatoxins are a group of mycotoxins principally produced by Aspergillus flavus and A. parasiticus, which are both natural contaminants of food and feedstuff. Aflatoxin B1 is the most prevalent member of this group that is normally detected and is the most powerful hepatocarcinogen known. Few naturally occurring episodes of aflatoxicosis in horses have been reported in the literature. Indeed, the published information about aflatoxin exposure, metabolism and the effects on horses is limited and controversial, possibly indicating a lack of awareness rather than the rarity of the occurrence. The target organ in horses, as in other animal species, is the liver and horses suffering from aflatoxicosis show signs of inappetence, depression, fever, tremor, ataxia and cough. Necropsy findings include a yellow-brown liver with centrilobular necrosis, icterus, haemorrhage, tracheal exudates and brown urine. A possible link between aflatoxin exposure and chronic obstructive pulmonary disease has been hypothesised.