EPM

Early detection and treatment are the keys to helping a horse recover from this neurological disease.

- Laurie Bonner

When your previously sure-footed horse starts to stumble regularly…. Or you notice his lip drooping and he’s dropping feed…. Or his gaits just seem to lack that usual smoothness under saddle….

Signs like these may be subtle, especially at first, but it is not good to overlook them. In fact, any persistent change in the way a horse uses his body---including his resting stance, his gaits, how he carries his tail, the pattern of his sweat, generalized weakness, a drooping ear or tilted head--- could be a sign that he is developing a neurological disorder.

And one common neurological disease affecting American horses is equine protozoal myeloencephalitis (EPM). Horses may develop EPM after ingesting feed or water contaminated with Sarcocystis neurona, a one-celled organism called a protozoan, that is spread by opossums and carried by other animals. Less commonly, a different protozoan called Neospora hughesi may also cause EPM.

Most horses who encounter the organisms that cause EPM put up an immune response that fights off the infection. Sometimes, however---in less than 1 percent of exposed horses---the protozoa cross into the central nervous system and damage the brain and spinal cord. Several drug treatments are available that can curb the protozoal infection, but the damaged nerves will still require up to a year or more to heal, and some horses never recover completely. Relapses are common if the protozoal populations are able to rebound after treatment ends. A horse’s chances of a full recovery are better when treatment is started early, before the damage is too severe.