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Days in Horse Country – Equine Protozoal Myeloencephalitis (EPM)
In the 1990s,
a disease caused by an organism called sarcocystis neurona began gaining some
attention among horse owners. Called
equine protozoal myeloencephalitis (EPM), the disease caused severe
neurological damage in horses that oftentimes became permanent. It is the most common neurological disease in
horses today. It is seen mostly in the
United States but it has also presented in southern Canada and in South
America.
The organism that causes EPM is a single-celled parasitic protozoa that is found in the muscles of contaminated birds. When these birds die and are eaten by scavenging opossum, the parasite is excreted in the opossum’s waste. If a horse eats or drinks where the opossum has defecated, the parasite is then ingested by the horse, thus infecting it too.
When a horse is infected with the organism responsible for EPM, inflammation occurs in the central nervous system. Symptoms can include seizures, depression, blindness, deafness, facial paralysis, lack of coordination.
Veterinarians treat EPM with drugs designed to kill the offending organism but these have mixed results. Some horses recover completely while others are beyond help and must be destroyed.
The best way to prevent EPM is to keep your horse healthy, since a strong immune system can fight off the organism in the event of exposure. Keeping opossums off your property is also a good way to avoid exposure to EPM. Never leave pet food or garbage out that will attract these scavengers. Keep your horse’s grain securely covered and your hay behind closed doors is possible. Also, ensure that your horse’s water supply is clean and out of reach of oppossums.
Michael