Videos of Horses With Equine Protozoal Myeloencephalitis (EPM)

What EPM Symptoms Look Like

Veterinarian during medical exam of a horse
A veterinarian inspects horse. Alina Solovyova-Vincent / Getty Images

One of the difficulties with recognizing the signs of Equine Protozoal Myeloencephalitis (EPM) is knowing what they look like. There are many terms that veterinarians use that are unfamiliar to the average horse owner to describe the various stages and symptoms of the diseases. And there is no set of exact symptoms, some of the symptoms may be vague or are not typical. That makes it much harder to diagnose.

One of the best ways to clear up the confusion is to look at horses with the disease to see how each symptom presents itself. And, you can see some of the tests used to physically test for the instability that often accompanies the disease. This is impossible when there are no horses with EPM around—which of course is a good thing. Thanks to online video on however, you can get a look at what the various symptoms can look like and how EPM is diagnosed. There are also some interesting treatments being researched.

Symptoms and Field Tests

Pathogenes Inc. has posted several videos of EPM affected horses. Here you will see what the various symptoms look like. The collection also has an instructional video of how a field test is prepared. If you have a horse that you suspect has EPM, this page gives instructions on how to make a video so that the symptoms can be emailed to them.

An owner demonstrates how muscle and balance tests are done when diagnosing EPM. Doing these tests on your own shouldn’t be a substitute for having the horse diagnosed by a veterinarian. With EPM, the faster and more consistent the veterinary care a horse gets, the more likely the horse has a chance at recovery.

This horse has a suspected case of EPM. The video shows the possible evidence of the parasite’s infection. 


This video clip was taken in 2008 and shows a pinto horse with EPM that is very weak. This horse is unable to organize its limbs to back up with coordination.

Muscle Atrophy

No video here, but this photo clearly shows a good example of muscle atrophy. This is when the muscle becomes shrunken and is one of the many devastating symptoms of EPM over time. On this horse, there is profound atrophy on one side of the haunch, while the other side remains normal. Unfortunately, the atrophy cannot be treated and is permanent.


 Dr. Samuel Hurcombe of The Ohio State University shows a horse with EPM symptoms in this video and discusses possible treatment strategies for dealing with the disease.

Not all horses with EPM can be saved, unfortunately. This video shows a chestnut horse with the disease that was a few days later humanely euthanized for safety reasons. Unstable horses can hurt themselves or anyone close enough to be in the way if they fall.

Advances in medical sciences have benefitted our horses and one of the most exciting fields is stem cell therapy. In this video, the progress of a gaited mare who has been given stem cell therapy is tracked over six months.

If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.