A recent question Why can't my rabbit lift it's head? suggested that botulism in hay could be problematic for some pets. When I think of Botulism I think of poorly canned food, how could it occur in hay? What are the risks for my pet?


Botulism is an illness induced by toxins produced by the bacteria Clostridium botulinum. The bacterial spores are present in soil and water. When enclosed in a warm, moist, oxygen free environment the spores grow creating Botulinum toxin, this toxin can be fatal to humans and animals. The toxin works by blocking nerve impulses leading to paralysis. When death occurs it is generally related to paralysis of breathing muscles or thrombus (stroke).

Because the botulism spores are present in the soil, any grown product including hay can be infected. While the the spores are not toxic, if the spores have a good place to grow they can create the toxin. With hay this can occur when the hay is baled at to high of a moisture content, then placed in plastic bags (ref). Additional causes of botulism in hay include; dead animals accidentally baled in the hay (ref) or hay contaminated with bird or other feces containing the toxin (ref).

The toxin is a protein that can be killed (denatured) through exposure to sunlight (1-3 hours) or heat {80°C (176°F) for 20 minutes}(ref), even 12 hours of exposure to air can be sufficient (ref) to destroy the toxin.

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