Major Uses

Ponazuril is an antiprotozoal medication used to reduce the severity of equine protozoal myeloencephalitis (EPM) in horses. It is also used in the treatment of coccidia infections in horses and small animals. Coccidia are single-celled organisms that are capable of producing potentially-fatal diarrhea in most birds and mammals. Ponazuril kills the coccidia to clear the infection, eliminate symptoms, and prevent complications.

Ponazuril comes in an oral paste for treating horses, and this paste is sometimes diluted and administered orally to cats and dogs to control coccidia infections. Horses must undergo treatment for 28 days for EPM, while small animals are treated with the compounded formula for 1 to 5 days for coccidia infection. The drug may be used to treat other conditions.

Common Precautions

Ponazuril has been shown to cause stomach upset and a rash around the mouth in horses. It is not clear what side effects are associated with use of the drug in small animals. Keratoconjunctivitis sicca, mild colic, and seizures are possible in animals undergoing treatment with this drug.

Ponazuril is not for use in horses intended to be used as food. It is not clear if ponazuril is safe for use in pregnant or lactating animals. Dogs receiving pyridostigmine for myasthenia gravis may experience extreme weakness when given ponazuril.

Ponazuril should not be used in animals with a known allergy or hypersensitivity to the drug. Diarrhea has been reported in cases of ponazuril overdose. Any known or suspected overdose should be reported to a veterinarian right away.


Ponazuril should be stored at room temperature, in its original packaging, and out of the reach of children and animals.


Ponazuril is available as a 150 mg/gram paste for oral use in horses. Feline and canine formulas require compounding. The typical dose for treating equine protozoal myeloencephalitis in horses is about 2.5 mg/lb (5 mg/kg) once daily for 28 days.

Doses may vary in different species, when the drug is given by a different route or concurrently with other medications, and with regards to a patient's age, breed, and health status. A veterinarian's dosing instructions and/or those printed on the medication label should be followed closely.

If a dose of this medication is missed, it should be taken as soon as possible. If it is almost time for the next dose, the missed dose should be skipped and the normal schedule resumed. Two doses of this drug should not be taken at once.

This information is for general reference only and should not be used for the diagnosis or treatment of any condition of your pet. It's intended as a general reference, this information may not include all possible uses, precautions, directions, reactions (including allergic), drug interactions, or withdrawal times. Always consult your local veterinarian and have your pet examined for any advice concerning the diagnosis and treatment of your pet, including which products and doses are most appropriate. Any trademarks are the property of their respective owners. VetDepot is not a pharmacy. All prescription products are dispensed by our Pharmacy Partner. Article last updated 2/2014.