Horses with botulism who lose the ability to stand are far less likely to survive than those who remain on their feet, according to a retrospective study from the University of Pennsylvania’s New Bolton Center.

Caused by the ingestion of toxins produced by Clostridium botulinum bacteria, botulism is characterized by progressive paralysis that eventually causes death as the horse loses the ability to swallow or breathe. Most equine cases of botulism occur after horses ingest tainted hay or other forage.

The researchers examined the records of 92 horses with botulism admitted to the university hospital over a 24-year period. The data revealed that while the overall survival rate was 48 percent, it was significantly higher—67 percent—for horses who were still able to stand when they arrived at the hospital. Among horses who were unable to stand when they arrived, only 18 percent survived. The prognosis was best for horses who stayed on their feet throughout their hospitalization; they had a 95 percent survival rate.

The researchers also note that complications, such as pressure sores or colic, were common but did not influence survival rates.

Reference: “Outcome of adult horses with botulism treated at a veterinary hospital: 92 cases (1989-2013),” Journal of Veterinary Internal Medicine, November 2014

This article first appeared in EQUUS issue #450

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