New EPM drug approved

LEXINGTON, Ky. - The Food and Drug Administration has approved the drug ponazuril as a treatment for the equine neurological disease EPM (equine protozoal myeloencephalitis).

The new drug, marketed by Bayer Animal Health under the trade name Marquis, is an oral paste that is available by prescription from a licensed veterinarian. The recommended dose in adult horses is five milligrams per kilogram, once a day for 28 days.

Ponazuril is a derivative of toltrazuril, a medicine commonly used to treat diseases in poultry, swine, and other animals. Toltrazuril, sold by Bayer in Canada under the trade name Baycox, also has been tested as a possible treatment for EPM but is not available in the United States except by special veterinary application.

Other EPM treatments may be on the way. Blue Ridge Pharmaceuticals also has submitted an application for approval for its medication nitazoxanide, which currently is undergoing trials in horses.

EPM is widespread throughout North and South America and the cause of potentially life-threatening neurological problems in horses such as severe lack of coordination and wasting of muscles.

Though the FDA estimates that some 80 percent of the horses in the United States may be exposed to the disease, the department said that only about 1 percent actually develop clinical symptoms and require treatment.

The standard treatment for the disease has been a combination of pyrimethamine and sulfadiazine given for months at a time.