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(Sulfadiazine/Pyrimethamine Oral Suspension)

an FDA-approved, safe and effective treatment for horses with EPM

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Specimen Label

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Equine protozoal myeloencephalitis (EPM) is a nervous system disease caused by the protozoa Sarcocystis neurona. Horses develop the disease by ingesting contaminated feedstuffs. The definitive host is the opossum, but intermediate hosts have been identified as the nine-banded armadillo, the striped skunk and the raccoon.

EPM is an elusive disease as it presents highly variable clinical signs that may range from head tilt, ear droop, blindness, seizures, inability to chew or swallow, gait abnormalities, stumbling, muscle atrophy, weakness, incoordination, ataxia, or depression.

Testing and development of an early, effective treatment plan should be considered. It has been estimated that up to 55% to 65% of horses respond favorably to treatment. However, it is further estimated that a small percentage (no more than 10%) of treated horses do recover completely.

ReBalance Antiprotozoal Oral Suspension, when administered under labeled conditions, is an FDA-approved, safe and effective treatment for horses with equine protozoal myeloencephalitis (EPM) caused by Sarcocystis neurona. The active ingredients in ReBalance, sulfadiazine and pyrimethamine, are a well-known therapy for treatment of this disease. The two different antimicrobial agents inhibit folic acid synthesis at two different sites in the same synthetic pathway. The combination of sulfadiazine and pyrimethamine is synergistic, with the drug combination having an antiprotozoal effect.

ReBalance® Benefits
  • Proven safe and effective
  • Cost-efficient
  • Easy administration
  • Oral suspension
  • FDA-Approved
  • From A Name You Can Trust

This is Rio who was diagnosed with EPM by a veterinarian
(video shows signs of EPM before treatment).
Video courtesy of Bettina Martin.


1Granstrom DE. Understanding Equine Protozoal Myeloencephalitis: Your Guide to Horse Health Care and Management. The Blood-Horse Inc., 1997;10.

CAUTION:Federal law restricts this drug to be used by or on the order of a licensed veterinarian. See reverse for full directions for use.




For the treatment of horses with equine protozoal myeloencephalitis (EPM) caused by Sarcocystis neurona.

Active Ingredients

Sulfadiazine and Pyrimethamine

As with all drugs, side effects may occur. Worsened neurologic deficits (treatment crisis) may be observed during a period beginning with the first few days of treatment and ranging out to 5 weeks. In field studies, the most common side effect reported was generalized bone marrow suppression. Other, less frequent side effects included decreased appetite, loose stools, and mild colic. In most cases, the gastrointestinal signs were self-limiting and did not require discontinuation of treatment. ReBalance is not for use in horses with known hypersensitivity to sulfonamide drugs or pyrimethamine. Refer to the prescribing information for complete details or visit