An outbreak of equine botulism type A associated with feeding grass clippings.

The research article describes an outbreak of equine botulism type A in Northern California in 2010, which affected four horses that were fed grass clippings from a nearby park. The horses developed flaccid paralysis and died or were euthanized within 96 hours. The grass clippings were found to have traces of the botulism neurotoxin.

Outbreak Description

• In September 2010, an outbreak struck four horses in Northern California. The common factor among these horses was that they had all consumed grass clippings from a nearby park.
• The symptoms developed by the horses including a progressive flaccid paralysis, were clinically consistent with exposure to preformed Clostridium botulinum neurotoxin (BoNT).
• The four horses demonstrated severe cervical weakness within 48 hours of consuming the clippings. This manifested as an inability to raise their heads to a normal position.
• All four horses were either dead or had to be euthanized within 96 hours of consuming the grass clippings.

Postmortem Examination and Findings

• A necropsy was conducted on one of the dead horses for diagnostic examination.
• The examination revealed extensive edema, or excess fluid, in the nuchal ligament and inguinal fascia areas.
• Grass clippings that the horses had consumed were also analyzed. They were found to have preformed botulinum neurotoxin Type A.
• The presence of the neurotoxin in the clippings was confirmed through a mouse bioassay test.

Recommendations

• The research emphasizes the importance of early recognition of cases in order to intervene rapidly.
• Commencing treatment with the trivalent antitoxin product shortly following exposure is critical to mitigate the effect of the toxin.
• Furthermore, preventing exposure to the BoNT in the first place is key, and can be accomplished by ensuring horses do not consume spoiled forages like the contaminated grass clippings in this outbreak.