top of page
Horse Owner Information

Do you have a horse diagnosed with EPM or has had EPM?  Join us in our path to FDA licensing by talking to your veterinarian, fill out the owner information sheet, look at the study entrance requirements and sign up for our clinical trials. Your participation ensures that more treatments will enter the pipeline. Be sure and sign up for notification when we post a new blog.  The blogs will keep you in touch with our new research.

The first step to returning health to a horse that has been treated multiple times with EPM drugs is to have your veterinarian test them. Submit the serum sample to us and we will get your results back to your veterinarian quickly. If you don't know which tests to select, contact us.  We will consult with you and your veterinarian.

Equine protozoal myeloencephalitis is a rare disease!  What does rare disease mean?















You maybe here because you are not a veterinarian and you are lost trying to understand our information, we hear that a lot.  We get it, you are worried that your horse may have a life threatening disease.  You may find our Journeyman's Guide to Pathogenes Blogs useful.





Let us say upfront that equine protozoal myeloencephalitis  (EPM) and polyneuritis equi (PNE) are diseases that require knowledge and expertise that can’t be gleaned from the internet. Many lay suggestions on the web will ultimately make your horse unusable or unsalvageable.

Veterinary courses in biology, physiology, parasitology, clinical pathology, immunology and epidemiology are a foundation for understanding EPM and PNE. A veterinarian will seek advice from veterinary neurologists. Veterinary neurologists go to special meetings to discuss the newest ideas and research, veterinary neurologists are one link between bench scientists and the clinic.

If you suspect EPM or PNE your first stop is your veterinarian. 

We can’t catch you up on the foundation needed for you to diagnose and treat these diseases on your own.  If you call, we won’t discuss your case without your veterinarian—you will need to set up a 3-way call and we are happy to oblige.  We require a medical record and a veterinarian that has a valid client-patient relationship.  That is a law.  Dispensing medical advice without a veterinary degree AND a client patient relationship is illegal. We will discuss your case with your veterinarian when we have a consulting agreement in place.

A horse owner often knows when their horse is under the weather, before neuromuscular disease is advanced.  Our paper describing the Early Signs of Equine Protozoal Myeloencephalitis can help you recognize the earliest warning signs of disease. The paper is based on experimental infections. 

Sometimes signs aren't so vague, the horse can be severely wobbly (ataxic) or even so bad that they are unable to get up. And at other times, the horse has been suffering with EPM so long that a dull, distracted demeanor is accepted as "normal".

A therapeutic plan should include multiple exams following treatment and serum analysis when appropriate. 

The antibody analysis of serum is useful.  The tests that are selected help the veterinarian understand the disease process and select an appropriate treatment plan.


We use surface proteins from the S. neurona parasite to test the sample taken from the horse. We report the the serotype, there are three different serotypes that can infect your horse, often all three will . There are some proteins that are “common” to all coccidia and some that are specific to one of three individual serotypes of S. neurona. Non-specific tests, (IFAT, SAG 2, 4/3), measure the common proteins found on all protozoa, we don't find those useful. The serotype of S. neurona is determined by detecting antibodies to SAG 1, 5, 6.  The serotype is the level a horse can detect, genetic differences are left to the molecular biologists.

The S. fayeri test measures the amount of antitoxin found in serum.  Antitoxin is the immune reaction to disease causing proteins produced by pathogenic S. fayeri  which infect horses. Most horses have S. fayeri muscle cysts (EMS), only 6% of S. fayeri strains produce disease-causing toxins.

A common factor in diseases caused by S. neurona and S. fayeri, (disease caused by either of these organisms is called sarcocystosis), is inflammation. Inflammation is measured by a serum CRP test. Horses that respond to anti-protozoal treatment without a reduction in CRP values eventually relapse. CRP may be elevated due to  infections other than Sarcocystis.


The Cliffs Notes for relapsing EPM are:

1-three conditions are associated with sarcocystosis: S. neurona, S. fayeri toxicosis, and polyneuritis; polyneuritis can be non-demyelinating or demyelinating;

2-the neurona-associated sarcocystosis group describes only 8% of chronic, relapsing/remitting disease;

3-autoimmune polyneuritis, horses with antibodies against the myelin P2 protein, a protein that covers nerves, is found in 43% of relapsing horses;

4-S. fayeri antitoxin is detected in 49% of horses with chronic neuromuscular disease;

5-the three conditions require different treatment.

A plan is needed to keep these horses healthy. The most crucial aspect of disease management is clinical exam by your veterinarian.  The veterinarian has the most up to date treatment protocols.  Testing the serum for CRP levels can let the veterinarian know if the inflammation is controlled.

Click to stop and start

bottom of page