Health & fitness
The outbreak of botulism in a central Pennsylvania farming community was reported to be caused by contaminated hay.
A pre-Christmas Sunday farm gathering near Myerstown, Pa. turned deadly for at least 15 of the 45 to 50 buggy horses who transported families to the event on Golf Road in Lebanon County.
All the horses who attended were either turned loose in a large paddock or tied. Most if not all had access to baleage. After the gathering the horses were harnessed and returned with their respective human families to their home farms.
The first signs of trouble came several days later when area veterinarians Drs. David Nirschl of Bernville, Pa. and Jeffrey Edelson of Manheim, Pa. were called out to treat eight horses at different locations. All had been at the Sunday gathering.
Within days all eight were dead. A farm mule also died. The diagnosis of the eight seen by the veterinarians (three by Nirschl and five by Edelson) was botulism, a high-fatality disease caused by a powerful toxin spawned by the bacterium Clostridium botulinum.
Another seven horses who been at the Sunday gathering also died. They had been seen by other veterinarians and euthanized or died before being treated, Nirschl said.
According to Dr. Amy Johnson, assistant professor of large animal medicine and neurology at the University of Pennsylvania's New Bolton Center, the fatality rate for botulism is about 70 percent.
The most common cause of botulism is ingestion of the toxin through contaminated forage. In the Myerstown Christmas outbreak, the attending veterinarians both said it was probably from a baleage - hay that has been compressed into large round bales and wrapped in layers of plastic.
It had been a wet month and the hay fed to the waiting horses was probably wet, muddy and trampled - ideal conditions for the contamination of the forage by toxins from putrefying carcases of birds, rodents and other animals.
More rarely, the bacteria can enter the equine body through a deep wound or can be ingested as spores in the soil.
Once down, horses are unlikely to recover and euthanasia is usually advised.
Treatment for botulism, once contracted, is expensive, difficult and not guaranteed to work. Although the anti-toxin has come down in price from $2,500 to $600-$700, said Johnson, the intensive and prolonged after-care involved makes it much more expensive.
Far more effective and cheaper is prevention by vaccination and by providing clean and dry forage and water.
Asked what could be done to prevent botulism outbreaks, Edelson suggested better regional education for farmers and families who rely on horse power for farm work and for transportation.
'I'd be delighted to give a lecture on botulism," said Edelson. He said a well-known and situated organization such as Lancaster Farming would be an ideal facilitator for a seminar of this nature.
According to the veterinarians interviewed for this report, botulism is not contagious from horse to horse, nor from horse to humans.
Cattle are more resilient to the botulism toxin than horses, said New Bolton's Johnson. She also said that since botulism is more common in southeastern Pennsylvania and surroundings than it is in most other parts of North America owners in this region are urged to vaccinate their horses.
Early diagnosis is difficult because the behavior of horses could look like other conditions such as colic, which is what the farmers in the Myerstown outbreak were reporting to Nirschl. Signs may include difficulty chewing and playing with food and water in their buckets. Paralysis eventually sets in as the bacteria block the nerve impulses and weaken the muscles.
A leading member of the community where the outbreak occurred declined - through Nirschl - to speak to this reporter for this report.