Botulism in Horses: Prevention of a Devastating Neurological Disease

Botulism is a potentially fatal toxin-mediated disease in horses causing progressive paralysis, but vaccination and proper feed management prevent most cases.

Key Facts

Equine botulism is caused by Clostridium botulinum toxin affecting the neuromuscular junction
Type B botulism is most common in horses, primarily from contaminated hay or soil
Shaker foal syndrome in young foals is a specific form of type B botulism
Signs progress from difficulty swallowing to muscle weakness and respiratory failure
Botulism antitoxin is available but most effective when given early in disease
Vaccination with botulism toxoid is highly effective in endemic areas

Welfare Considerations

Botulism causes profound welfare suffering: progressive paralysis while the horse remains conscious creates intense distress as the animal loses the ability to swallow, stand, and eventually breathe. Surviving horses may be recumbent for days to weeks requiring intensive supportive care. Prevention through vaccination is simple and highly effective, making botulism cases in vaccinated horses from endemic areas largely avoidable. Feed management is the primary prevention in non-endemic areas: botulism toxin can develop in poorly fermented silage or wet hay, and any feed that smells off should be discarded.

What You Can Do

Vaccinate horses annually with botulism toxoid if you are in an endemic area
Never feed suspect silage or haylage - discard any big bale forage with visible mold or off odors
Recognize early botulism signs: difficulty swallowing, weakness, tongue tone loss - seek emergency care
Ensure foals in endemic areas receive botulism vaccination as part of early life immunization
Test water sources if moving horses to historically endemic areas
Contact your vet about regional botulism risk before establishing a vaccination program