As Halloween approaches, we think of jack-o-lanterns, ghosts, goblins and, of course, witches. The most famous were the witches of Salem, Massachusetts. The story began when two girls, ages 9 and 11, started contorting themselves into strange positions and having spasms. More and more people were affected, showing similar signs as well as hallucination and psychotic episodes. The local reverend attributed these behaviours to witchcraft and the Salem witch trials ensued. Similar stories have been noted in history, from the Dancing Plague of the Alsace region in the 1500s and St. Anthony’s fire of the Middle Ages.
Several scientific accounts attribute these behavioural changes and skin lesions to ergotism (ergot poisoning) caused by the ingestion of alkaloids produced by the fungus, Claviceps purpurea, which can commonly affect rye grain.
It is believed that the moist conditions of 1691 may have contributed to moldy rye grains, and consumption of infected bread, particularly young girls, may have caused the strange behaviours of Salem. In fact, one of the compounds produced ergotamine, is a precursor for lysergic acid, similar to lysergic acid diethylamide (LSD).
Could infected rye or ryegrass be the cause of your horse’s odd behaviour? Chances are slim. Firstly, today’s rye grain is carefully grown and harvested to avoid mold production, and to sort out any of the seed-like “slerotia” that may be found among the grains of rye. Second, ergotism due to Claviceps is rare and doesn’t appear to affect the horse as much as other species (unlike ergot alkaloid poisoning from infected fescue grass or hay, which typically only affects pregnant/nursing mares).
There are only a few reports of horses developing staggers due to Claviceps. While it is a fun tale to tell around All Hallow’s Eve, horses don’t turn into witches just from eating some rye – but you might!