Ponazuril is an anticoccidial (antiprotozoal) compound with activity against several genera of the phylum Apicomplexa. Ponazuril (also known as toltrazuril sulfone) is a metabolite of the poultry antiprotozoal drug toltrazuril. Ponazuril is a triazine-based drug that acts to inhibit enzyme systems in protozoa and/or decreasing pyrimidine synthesis.

​Ponazuril is indicated for the treatment of equine protozoal myeloencephalitis (EPM), which can be caused by either of two related protozoan parasites, Sarcocystis neurona and Neospora hughesi, although S. neurona is the most frequent etiologic pathogen. 

EPM is a progressive, degenerative neurological disease of the central nervous system that has been described in horses for decades. The disease is one of the most commonly diagnosed neurological disorders of horses in the Americas. While great strides have been made throughout the last decade in an effort to understand EPM, many questions remain unanswered concerning its etiology, pathogenesis, occurrence, treatment, and diagnosis. Clinical improvement is noted in 60% to 75% of horses treated with ponazuril, however.1

Ponazuril Use in Companion Animals

While ponazuril is labeled (FDA-approved) for use in horses, it is also used in cats, dogs, rabbits, birds, and reptiles to treat protozoan and coccidial infections (“off label” or “extra label”).2 Coccidia infections in particular are relatively common in puppies and kittens with affected pets usually presenting with diarrhea. These infections are so common, in fact, that many animal shelters prophylactically treat puppies and kittens upon arrival.3 Ponazuril has also been useful in treating Neospora caninum, a protozoan parasite that affects a multitude of species.2 

Coccidia are single-celled organisms that attack intestinal cells. In young animals (puppies and kittens in particular), this can cause potentially life-threatening diarrhea. Most mammals, birds, pets and livestock are susceptible to coccidial infection, and some species of coccidia can be transmitted to humans. Medications typically used to treat coccidiosis are often called coccidiostats, which indicates that they interfere with coccidian reproduction rather than killing the parasite outright.

The use of ponazuril reflects a new approach to treatment, in that ponazuril actually kills the coccidia.3 This facilitates a faster response to treatment and shorter course of therapy. In the case of cats and dogs, the fact that ponazuril is manufactured for horses and comes in paste form often makes this medication impractical for small animal use. The paste can be diluted and used orally in dogs and cats, but there are increasing numbers of veterinary custom compounding pharmacies that prepare ponazuril formulations in concentrations tailored specifically for small animals.

Side effects with the use of ponazuril are reported as minimal, with skin rash occasionally reported in individuals. Keratoconjunctivitis sicca (KCS) has occasionally been reported in dogs, especially breeds with a predilection towards developing KCS or when the drug was given in higher quantities.2

Where to buy Ponazuril

Ponazuril is available in the U.S. through several pharmaceutical manufacturers and through veterinary custom compounding companies. PONAZURIL 100 MG/ML 240ML ORAL SUSPENSION by NexGen provides a superior, easily-assimilated alternative for the treatment of protozoan and coccidial infections in both horses and companion animals.

Please consult your veterinarian prior to beginning any treatment regimen.

FOR RX ONLY: A valid prescription from a licensed veterinarian is required for dispensing this medication.

1Howe DK, MacKay RJ, Reed SM. Equine protozoal myeloencephalitis. Vet Clin North Am Equine Pract. 2014 Dec;30(3):659-75. doi: 10.1016/j.cveq.2014.08.012. Epub 2014 Nov 6. PMID: 25441115.

2Plumb’s Veterinary Drugs. 

3Litster, Annette & Nichols, J. & Hall, K. & Camp, Joe & Mohamed, Ahmed. (2014). Use of ponazuril paste to treat coccidiosis in shelter-housed cats and dogs. Veterinary Parasitology. 202. 10.1016/j.vetpar.2014.03.003.