Eventually they die because their respiratory muscles become paralysed or because they get other health problems from being down. Since large wrapped round bale haylage came into common use, there have been several reports of groups of horses developing botulism after eating this type of feed. It was first reported in Great Britain but has also occurred in Canada. In some of these outbreaks, the haylage looked and smelled spoiled. In others, the bales did not look as if they were spoiled but horses eating them developed botulism.
Botulism is difficult to treat.
It is most beneficial if used when animals are first seen to be sick. With supportive care, horses can recover but, if they are exposed to a large amount of toxin, most will die despite treatment. This vaccine protects against type B botulism but not other types. This information is provided as a public service, but we cannot guarantee that the information is current or accurate. Readers should verify the information before acting on it.