How Long Do You Use EPM Treatments in Horses?

EPM, or equine protozoal myeloencephalitis, is a neurological disease that is treatable but not always curable in horses. Though it is frustrating and expensive to diagnose and treat, several drug and alternative options are available. EPM has many possible symptoms. If you notice that your horse is off balance, losing muscle, behaving as if he is tired or stumbling more than he has in the past, contact your veterinarian to test for EPM. The chances of a full recovery depend on the amount of nerve damage sustained by the horse, as well as prompt diagnosis and treatment.

  1. Pyrimethamine/Trimethoprim/Sulfadiazine

    • The combination of sulfadiazine, trimethoprim and pyrimethamine is a pioneer treatment for EPM. It takes the longest amount of time to benefit the horse compared with other drugs: approximately three to seven months depending on the severity of symptoms and the speed of diagnosis. This combination drug occasionally causes anemia in the horse due to an inability to absorb folic acid. It is available from several compounding pharmacies in a flavored powder for ease of administration.

    Protazil

    • Protazil (diclazuril) is a relatively safe treatment option, showing no adverse effects in field trials. Protazil is administered for 28 days, with further testing to examine the efficacy of the drug in the horse being treated. Though it is one of the more expensive options, Protazil comes in an easy to administer alfalfa pellet that you can pour over your horse's feed.

    Marquis

    • Marquis (ponazuril) is an herbicide and is safe in high doses in horses and other mammals. It is administered over 28 days in an oral paste form. The horse is retested after treatment to ensure that the EPM protozoa have been killed. If a horse relapses, a second phase of treatment ensues. For the first four days of relapse treatment, a much higher dosage is given; a maintenance dose is recommended for the remaining weeks. Consider adding extra fat to your horse̵7;s diet to aid in the absorption of Marquis.

    Alternative Therapies

    • Several alternative treatment options can complement a traditional medicinal approach to EPM. Vitamin E promotes regeneration of healthy nerve cells. Colostrum adds immune system support. Acupuncture can be helpful during and after treatment of EPM to maintain immune system stability and emotional balance. Pau d'Arco is an herb that is said to increase a horse's immune system defense, cleanse the blood and help fight infection. One teaspoon or tablespoon of the herb daily is sufficient for long-term use.