Let's Talk About Equine Protozoal Myeloencephalitis (EPM)

Let’s talk about Equine Protozoal Myeloencephalitis, or EPM.

If you are a horse owner, you have most likely heard of EPM. The disease is caused by

a protozoan parasite and affects the central nervous system of the horses it infects.

A horse becomes infected by ingesting the feces of an opossum carrying this protozoan parasite. Feces can be present in food and water troughs, among other places.

Did you know that through studies, an estimated 50% - 90% of horses in the United States are exposed, but less than 1% show clinical signs of the disease annually?

Most recorded Canadian cases of EPM occur in horses that originated from the United States, making EPM exceptionally rare in this country. Studies also show that although Opossums are definitive hosts of EPM, they are not natural carriers, despite popular belief. They contract the disease by eating carrion including decaying raccoons, skunks, and even cats.

Although some may believe that removing or even killing opossums is the solution to keeping horses safe from EPM, this practice does not hold water. When one species is moved out, it invites other species to move in, causing defects in the natural ecosystem. This could mean more opossums will take over the area, or more raccoons, skunks, and rats, who are far more likely to carry infectious diseases. Opossums are resistant to many diseases which affect other mammals.

As far as precautions go, barn and outdoor cats should be vaccinated, in good health, and spayed or neutered whenever possible to prevent an abundance of carrion in certain areas. It is also important to store feed sanitarily and to dispose of any carcasses on your property, properly and with haste.

Coexistence is key in cases like these. Opossums eat insects and other bugs that affect gardens as well as keep local rodent populations in check. They are North America’s only marsupial. If you or a fellow horse owner finds an Opossum on their property, please call our centre at (604) 530-2064 to get the best advice on the situation at hand, instead of resorting to removal or destruction. We will be happy to help you out!