A serious neurological disease, EPM is caused by a parasite. This parasite develops in animals like raccoons and skunks, and opossums feed on these animals after they die and ingest the parasite. The parasite is passed through the opossum’s feces, which a horse may unintentionally consume while eating contaminated feed or hay, or grazing in a contaminated field.
EPM will have two main visible symptoms—loss of muscle mass and loss of coordination. The muscle loss will occur mainly in the haunches, the back and the withers. And the loss of coordination is usually something like the dragging of a hoof, or a horse will begin to stumble.
Signs of EPM can easily be confused with other problems. That is why you must take your horse to a vet, so testing can be done. Early detection and treatment of the disease improves your horse’s chances of returning to good heath and peak performance.
There are several tests for EPM, and some blood-work will most likely be done if your horse is infected, but the most accurate test is the Western Blot Test.
Prevention is the key to making sure your horse doesn’t contract EPM. Keep your barn area free from things that will attract opossums, if possible. Pet food, garbage and open grain bags all attract these animals. Keeping grain in a large plastic bin is always a good idea. Possibly consider live traps to relocate any opossums in your area. Do all that you can to keep your horse healthy, because if you’re like me, then your horses are the center of your life.