## Overview Equine protozoal myeloencephalitis (EPM) is a neurologic disease caused by infection of the central nervous system with Sarcocystis neurona (most cases) or Neospora hughesi. It produces highly variable signs, most often asymmetric ataxia and muscle atrophy. It occurs in the Americas. ## Causes Ingestion of sporocysts shed by opossums (for Sarcocystis neurona), followed by aberrant migration into the nervous system. ## Diagnosis Neurologic examination plus serum and cerebrospinal fluid antibody testing showing intrathecal antibody production. Other causes of ataxia are excluded. ## Treatment FDA-approved antiprotozoal drugs (ponazuril, diclazuril, or sulfadiazine/pyrimethamine) for 28 days or longer, plus supportive care and anti-inflammatories. ## Recovery and Prognosis Approximately 60 to 70 percent of treated horses improve. Complete recovery is less common. Relapse can occur. ## Prevention Reduce opossum access to feed. No fully effective vaccine is available.
asymmetric ataxia (often worse behind); muscle atrophy; stumbling; cranial nerve signs in some cases; can be acute or progressive
## Overview Equine protozoal myeloencephalitis (EPM) is a neurologic disease caused by infection of the central nervous system with Sarcocystis neurona (most cases) or Neospora hughesi. It produces highly variable signs, most often asymmetric ataxia and muscle atrophy. It occurs in the Americas. ## Causes Ingestion of sporocysts shed by opossums (for Sarcocystis neurona), followed by aberrant migration into the nervous system. ## Diagnosis Neurologic examination plus serum and cerebrospinal fluid antibody testing showing intrathecal antibody production. Other causes of ataxia are excluded. ## Treatment FDA-approved antiprotozoal drugs (ponazuril, diclazuril, or sulfadiazine/pyrimethamine) for 28 days or longer, plus supportive care and anti-inflammatories. ## Recovery and Prognosis Approximately 60 to 70 percent of treated horses improve. Complete recovery is less common. Relapse can occur. ## Prevention Reduce opossum access to feed. No fully effective vaccine is available.
asymmetric ataxia (often worse behind); muscle atrophy; stumbling; cranial nerve signs in some cases; can be acute or progressive