Equine protozoal myeloencephalitis

Equine protozoal myeloencephalitis (EPM) is a disease that affects the central nervous system of horses.

[1] The parasites create lesions in both the brain and spinal cord of the affected horses leading to neurological issues.

In the laboratory, raccoons, cats, armadillos, skunks, and sea otters have been shown to be intermediate hosts of S. neurona.

Clinical signs among horses with EPM include a wide array of symptoms that may result from primary or secondary problems.

In experimentally infected horses, very early signs included loss of appetite, decreased tongue tone, facial paresis, altered mental status, generalized weakness, and lameness.

In cases where S. neurona is found in the CNS, white blood cells probably play a role in the parasite's penetration of the blood-brain barrier.

Another option is a cervical radiograph, which can identify any compression in the spinal cord that may cause a horse to lose coordination.

[5] A veterinarian can also draw blood and spinal fluid and send it to a lab to confirm if a horse has been exposed to opossum feces.

Labs can perform immunodiagnostic testing on spinal fluid to evaluate the production of antibodies that fight against these parasites.

Currently, three FDA approved treatments are available in the US: ReBalance (sulfadiazine and pyrimethamine), Marquis (ponazuril), and Protazil (diclazuril).

The use of anti-inflammatory agents such as banamine, corticosteroids, or phenylbutazone are often used to help reduce inflammation and limit further damage to the CNS.

[3] Later, in the 1970s, it was recognized by Mayhew and colleagues that the syndrome was associated with an infection by protozoa, and the current name of the disease, "equine protozoal myeloencephalitis", was coined.