Equine protozoal myeloencephalitis (EPM), a neurological disease, can affect equines of any age and sex and in any location throughout the United States.

Agent

Protozoa, Sarcocystis neurona

Vector

Opossum

Symptoms

• Asymmetric incoordination (incoordination on one side of the horse or the other)
• Loss of proprioception (loss of the sense of awareness of the position of the limbs)
• Depending on severity, various levels of seizures, muscle atrophy (leading to loss of ability to use muscles), and facial paralysis

Treatment

Antiprotozoal drugs, the most common being trimethoprim-sulfamethoxazole, an antimicrobial are used. Anti-inflammatory therapy is recommended, and supplements of vitamins E and folic acid may aid in treatment.

Prevention

Control the contact between opossums and horses in and around the barn. Keeping all food covered and out of reach is essential (especially if there is cat food around).

See Equine Protozoal Myeloencephalitis (EPM) for more information.