opossum has been determined to be a host within the cycle, with birds acting as
for the parasite. The incubation period for the disease is unknown.
EPM affects different neurons throughout the neurological system and can result in dragging or spastic gaits. One side of the body may be affected, but not the other. The organism can also cause muscle atrophy in the jaw and forehead. If it affects the cranial nerves, the horse may have problems eating or drinking, have facial twisting, or undergo changes in the position of the eyes and ears. Severe cranial infection can even cause bizarre changes in behavior or seizures.
Diagnosis of EPM is based upon finding antibodies or, more recently, a DNA detection test of either blood or cerebrospinal fluid. Blood antibody titers, however, should not be considered evidence of the clinical disease. Although spinal fluid samples are more difficult to obtain, they are more reliable. The DNA test is used to identify the presence of the organism in the spinal fluid.
The good news for horse owners is that EPM is treatable in the long-term with sulfa drugs and an antimalaria medication. Since these drugs can cause anemia, folic acid is added to the diet.
Vitamin E has also been found to aid in nerve healing and is added to the daily regimen. About 70 percent of horses respond to treatment, although the level of clinical response may not result in full recovery. Horses have been known to compete at the top levels after treatment.
Equine protozoal myelitis should be considered a common endemic, not epidemic, disease. Horse owners should treat the disease aggressively, knowing that this is one of the neurological diseases that justifies optimism. Your horse can get better if treated.