The recent outbreak in Northern Ontario, for example, took many researchers by surprise, as the disease is extremely rare in Canada. Practitioners are now beginning to suspect that many cases of botulism have been mis-diagnosed in the past. The increasing practice of feeding fermented silage products to horses is also having an impact. As more farms use these products, I think we'll be seeing more and more cases. It's important to understand how quickly this disease progresses.
Vaccination is obviously the first line of defense against botulism.
Any farm considering using haylage or silage products as horse feed should also consider doing regular pH testing. Whitlock notes that C. botulinum is very pH sensitive, and it thrives at a pH level over 4.5. Feedstuffs that test at a pH level below 4.5 are probably acid enough not to be contaminated with the toxin. Botulism at a glance Botulism is caused by a neurotoxin produced by the anaerobic bacterium Clostridium botulinum . The toxin produced by C. botulinum is one of the most potent known to man.