Horse owners and veterinarians frequently ask about the use of diclazuril to treat equine protozoal myeloencephalitis (EPM). Diclazuril is a triazine derivative used to treat coccidiosis in broiler chickens in Canada. It is not approved for use in the United States but can be imported under the FDA's Personal Import Policy. Its efficacy against apicomplexan protozoa suggests that it might be effective against Sarcocystis neurona, the causative agent of EPM. Possible benefits of diclazuril in the treatment of EPM include a shorter duration of treatment and lower cost compared with pyrimethamine and sulfonamides. One disadvantage is that diclazuril is available only in 20-kg sacks, so a larger quantity than is needed must be purchased. Another disadvantage is that a large volume of the product must be administered. Additionally, side effects, including worsening of clinical signs, colic, and leukopenia, have been reported. Another agent, toltrazuril, used to treat coccidiosis in swine, has also been suggested as a possible treatment of EPM. This drug is also not approved for use in the United States. Information on how to import agents under the FDA's Personal Import Policy is discussed.
