EPM has become a common clinical problem in the horse, being primarily a parasitic infection of the central or peripheral nervous system cased by Sarcocystis neurona.  The condition is commonly diagnosed in all breeds of horses and different levels of activity from the backyard companion to the elite dressage competitor.  When not managed properly and completely, EPM (equine protozoal myeloencephalitis) can lead to a career ending or worse, permanent neurological impairment in the horse, sometimes resulting in euthanasia.  In this case study, we will look at the bigger picture and how the EPM condition was managed by improving overall health in the patient rather than just relying on anti-protozoal medication.

EPM Management in QH Mare

EPM Management in QH Mare

A diagnosis of EPM in the horse has become commonplace over the past decade or two, which is rather unfortunate.  While we like to blame the opossum and other wildlife species, the truth is that the horse has to be susceptible to invasion and infection by the offending organism.  This has been demonstrated throughout time with many types of infections in both man and animal.  Just because a bacteria, virus, fungi, or parasite is present in an environment does not mean that the host will contract the disease or infection.  The perfect storm has to be present, which is an opening or weakness in the health of that horse or host, which allows not only for the organism to enter the body, but to replicate and thrive, creating clinical disease.

In the world of medicine, we have many tools to combat disease and infection.  In the case of EPM and other clinical infections in the horse, we have vaccines, antibiotics, antiprotozoals, and other medications to combat disease.  In truth, the EPM vaccine was a thing many, many years ago, but failed to prove efficacy for many reasons.  Even then, one can vaccinate a horse or any other species for an antigen, but this does not mean they are protected.  Many times it just leads to a false sense of security, causing us to avoid the truth path to a solution.  Antibiotics and antiprotozoal medications are also helpful and valuable, but they too do not always lead to a resolution, as many horse owners can testify to.

The truth is that the horse’s immune response is the first line of defense and if it is strong and healthy enough, infection will likely never occur or if it does occur, resolution is swift and complete.  As simple as this sounds and with all of the heavy marketing of supplements towards immune health in the horse, it seems even more straight forward, however, once again, this is an illusion.  There are many working ‘arms’ to the immune response in the horse, so enhancing that response may not be as simple as one would like.

Let’s look at a case study involving a horse with EPM and how she was treated effectively.

Quarter Horse with Relapsing EPM and Management

A 12-year-old QH mare was presented for clinical evaluation of persistently being ‘off’ or unsound for over 6 month’s time.  The mare had been used successfully as a barrel horse competitor for many years and until the past year, had rarely had any health or lameness problems. She is stalled by night and out on a small 2 acre paddock by day, fed 2 pounds of a commercial along with 4 heavy flakes of a Timothy hay, fortified grain in the evening, on a trace vitamin-mineral supplement once daily, Vitamin E supplement, and a chondroitin-glucosamine supplement for joint support.  She routinely has her hocks injected with a corticosteroid and hyaluronic acid generally once per year, but the owner notes that this past year, she received two injections separated by six months.  The mare is routinely vaccinated twice yearly and dewormed per the owner.

On physical exam, the mare was standing 15 hh and weighing approximately 1100 lbs.  Her ribs were not palpable even with moderate pressure.  She was standing quiet, with her head down, in an almost depressed fashion.  Cardiovascular and lung (pulmonary) evaluation were normal.  Digestive or gut sounds were also normal, possibly slightly decreased on some quadrants.  She was afebrile and slimy mucous was noted on the thermometer.  Her feces, noted in the trailer, were firm, brown in color with a slimy coating to the surface.  A quick oral examination noted a pink tongue, but slimy saliva which had accumulated in the corners of her mouth.

Upon further inquiry into the mare’s clinical history, the owner notes that over the past 4-5 years, she would have skin flare ups in the summer time, especially after heavy rains or damp weather.  The condition was never addressed by a veterinarian as the owner managed with topical remedies as needed.  Over the past year, the owner noted that the mare had become more and more sluggish, and her race times were becoming slower.  She did have an occasional cough with phlegm being expectorated, but this was not persistent.  The owner noted that her hind end seemed to be disconnected over the past year, sometimes having a mind of it’s own, and creating problems when navigating barrels.  This then led to a veterinary examination.

Per the owner, a veterinarian examined her horse six months ago, evaluating the hind limbs for lameness, which was not noted on flexion tests, or under saddle.  Radiographs were taken and indicated low grade degenerative joint disease of the lower hocks bilaterally, but the hocks were not sensitive to flexion.  The veterinarian then proceeded to perform a neurological examination which indicated conscious proprioceptive deficits in the rear limbs only.  This then led to testing serum for EPM antibody levels, which came back positive.  The mare was then managed with traditional anti-protozoal medications for 30 days at standard dosing, which failed to provide improvement.  Then, the mare was treated with double dose of the same medication for the next 30 days, which did appear to provide improvements, to the point that the mare was slowly returned to work.  On repeat serum sample testing, the mare’s titer did come down, but was still above normal.  Despite the improvements, over the past 60 days the owner has noted that the mare has again become sluggish and off in the hind limbs.

Given the history, the mare was evaluated for overall soundness, performing flexion tests and jogging in a straight line on both hard and soft surfaces.  Flexion tests were normal, with no pain elicited, but upon jogging, it was noted that the rear limbs were dragging at times with abnormal placements patterns, sometimes to the inside and other times to the outside.  A tail pull test was performed and it was noted that the mare could easily be pulled from one side to the other when walking in a straight line, indicating overall muscular weakness.  Anal tone was considered normal.  Conscious proprioceptive (CP) tests were done with leg and foot placement exercises, which the mare failed.  Overall, the clinical evaluation indicated neurological deficits which would coincide with the original EPM diagnosis.

Despite the owner desiring a ‘new’ medication to manage her mare and enable her to return to competition, a different approach was taken to address her overall health instead.

  1. Increased paddock time was recommended, increasing the space being offered as well as better management of the paddocks to allow for grazing and interaction with other horses.
  2. Hay was switched to an alfalfa/timothy blend to increase nutrient density and to take advantage of phytochemical benefits of alfalfa on metabolism, gut health, immune response, and overall cellular function.
  3. Grain was eliminated completely and the mare was switched to 1 pound of alfalfa pellets twice daily to serve as a ‘grain’ and a medium for supplement administration.
  4. All current supplements, including the vitamin-mineral supplement, vitamin E and glucosamine were discontinued.
  5. The mare was started on Cur-OST EQ Total Support at label doses twice daily for 14 days, along with the Cur-OST EQ Tri-Guggul supplement once daily in the evening.

The mare was re-evaluated in 30 days and there was marked improvement noted in her clinical attitude and movement.  She was more alert and responsive on examination, with her eyes brighter than prior.  Feces were now a green color with improved moisture and no noted mucous or slimy coating.  Upon neurological examination, the mare had improved by a few grades, but some mild deficits were still noted.  Overall, she was moving much better.  Foot care and proper balancing were addressed with the owner, instructing her on how to trim and improve overall foot travel.  This was especially important as the mare had not had proper farrier care in many months and due to the rear feet dragging at times, it was impacting overall foot balance and wear.  At this time, the owner was to continue the supplementation as directed above, but to decrease the frequency of the EQ Total Support to once daily, along with the EQ Tri-Guggul.  A concentrated blueberry powder was added to the regimen for antioxidant provision, digestive support, detoxification, and overall metabolic cellular health.

The mare continued to do well and was back in training with the owner within 60 days at full work.  She remained on the recommended diet and basic supplement recommendations.  The only change was a movement to the EQ Total Support Total Body supplement, which eliminated the need for all of the supplements, as this combined them into one easy to administer blend.

QH Mare with EPM Discussion

EPM can be a complex condition and directly involves the immune response and a breakdown or weakness in that defense mechanism.  This is what opens the door for an EPM infection.  Usage of anti-protozoal medications can be helpful, but in truth, they only reduce parasite loads to a lower level, in hopes that the immune response can then take over and remedy the problem.  In some horses, this is the case, while in others they either fail to respond to the medications or they relapse, as this mare demonstrated.  These are the times when the whole body needs to be addressed for optimal outcomes.  In truth, this approach should be taken as a first line of defense either with or without medications, as it could dramatically enhance the outcomes and eliminate relapses.

The mare in this case study demonstrated digestive weakness which was directly impacting the immune health.  When the digestive system is out of balance, not only are nutrients not properly extracted or utilized by the body from food sources, but inflammatory events ensue.  One main problem is toxin accumulation (ama or dampness), which results in weight gain, sluggishness, and discharges, not to mention a host of other health problems.  In this mare, the toxin accumulation was noted in the skin problems and the phlegm discharge with the intermittent cough.  It was also noted in the fecal material with the slimy, mucous coating and the sticky saliva.  The dampness can also impact behavior, either contributing to depression or anxiety at the other end of the spectrum.

The immune response is directly correlated to digestive health, which has been demonstrated in research and known in medical science for eons.  When digestive health is not optimal and balance, the immune response is often inferior and dysfunctional.  This is further worsened by what is termed ‘leaky gut syndrome’ and leakage of toxins (LPS) from the gut to the systemic circulation, creating a flare of constant low-grade inflammation in the body which can impact metabolism, circulation, joint health, hoof health, and many other problems.

The first step to resolving the problem is to eliminate contributors to the events which are present.  Stress is a huge culprit and thus, lifestyle changes were recommended.  Diet is another major contributor, and recommendations were made to alter the forage to improve nutrient provision and provide healing support to the digestive system.  Grains were eliminated due to the fact that first, the mare did not need grain supplementation.  There was no need for added calories to her diet as her body weight was actually heavy, not thin.  In addition, grains provide excess carbohydrates which can drift over to the hindgut and contribute to bacterial dysbiosis or imbalances.  Going further, it is in our experience that synthetic vitamin-mineral supplements and other non-whole food supplements tend to contribute to more digestive irritation and bacterial imbalances, which may be due to differences between synthetic and whole-food forms of nutrients and also added sweeteners and flavoring to mask those acidic ingredients.

The overall goal was to improve digestive health in the mare and with that, enhance immune and overall health.

The herbal blend, Cur-OST EQ Total Support was initially chosen due to it’s ability to help quench and control systemic inflammation naturally and support digestive health.  It has a mildly drying effect on the body due to a few herbs, which benefits digestion and aids in toxin removal.  It is very beneficial for many ‘easy-keeper’ types of horses for a variety of conditions.

In addition, the Cur-OST EQ Tri-Guggul was added for further digestive support.  This formula contains an ancient Ayurvedic digestive blend of herbs, including Guggul, which directly support digestion and aid in toxin removal from the body.

Further in the course of the mare’s therapy, a concentrated blueberry powder was added for further digestive, antioxidant, and detoxification support.  This is an incredible fruit with many health properties that can benefit many horses.  It is especially useful at managing metabolic related problems and aiding in weight management.

Through this approach, the mare recovered nicely and returned to active work.  A repeat serum antibody titer was not performed.  The mare was doing well in her work 8 months after the initial visit with no indications of relapsing or problems.  It is interesting to note that the following summer, the owner did not note any skin problems and her requirements for joint injections had also diminished.

For further education and resources:



Author:  Tom Schell, D.V.M, CVCH, CHN





Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.