Horse EPM: Equine Protozoal Myeloencephalitis Treatment

EPM is a serious neurological disease in horses caused by a protozoal parasite, requiring prompt diagnosis and treatment to prevent permanent disability.

Key Facts

EPM is caused by Sarcocystis neurona, a protozoa carried by opossums as definitive hosts
Horses are infected by ingesting feed or water contaminated with opossum feces
Signs range from subtle gait abnormalities to severe ataxia, muscle wasting, and recumbency
Diagnosis is challenging - blood and CSF tests measure antibody exposure, not active disease
FDA-approved antiprotozoal treatments include ponazuril, diclazuril, and sulfadiazine-pyrimethamine
Early treatment significantly improves outcomes; horses treated late may have residual neurological deficits

Welfare Considerations

Neurological symptoms from EPM cause fear and disorientation in horses who cannot understand their loss of balance and coordination. Severe cases involve falls and inability to rise, causing acute distress. Early recognition and prompt veterinary treatment are welfare imperatives. Minimizing opossum access to feed storage prevents exposure and represents a practical welfare-protective management measure.

What You Can Do

Store all hay and grain in opossum-proof containers or buildings
Report any suspected neurological signs in horses to your vet promptly
Request titer testing for horses with unexplained gait changes or muscle wasting
Begin treatment promptly if EPM is suspected - delay worsens neurological outcomes
Monitor treatment response monthly and continue full treatment course as prescribed
Rehabilitate recovered horses gradually with physiotherapy support if indicated