Botulism is a syndrome of neuromuscular weakness caused by the toxins of Clostridium botulinum. Whilst it can affect most mammals, the horse appears to be one of the more susceptible species. Intoxication can occur via ingestion of preformed toxins in spoiled foodstuffs, ingestion of spores with colonisation in the intestinal tract or the contamination of wounds by C. botulinum. Food-borne botulism is the most common worldwide, usually associated with spoiled roughage. Both individual cases and outbreaks have been reported, with generally a poor prognosis. Many affected horses succumb to recumbency and death/euthanasia shortly after onset of signs. Botulism should be considered a differential diagnosis for any horse displaying dysphagia or symmetrical neuromuscular weakness.