Ponazuril (INN, Toltrazuril sulfone), sold by the Bayer Corporation under the trade name Marquis, is a drug currently approved for the treatment of equine protozoal myeloencephalitis in horses, caused by Sarcocystis neurona. More recently, veterinarians have been preparing a formulary version of the medication for use in small animals such as cats and dogs against coccidia, an intestinal parasite. Coccidia treatment is far shorter than treatment for EPM. Ponazuril (INN, Toltrazuril sulfone) is useful for Antiprotozoal.