Neurologic

Equine protozoal myeloencephalitis (EPM), cervical vertebral stenotic myelopathy (wobbler syndrome), equine degenerative myeloencephalopathy, equine herpesvirus-1 myeloencephalopathy, and West Nile virus encephalitis are among the most frequently diagnosed neurologic conditions in North American horses.

Diagnosis involves a combination of neurologic examination, serology (serum and CSF antibody testing), and exclusion of other causes of ataxia. No single test is definitive; clinical context, geographic exposure risk, and response to treatment all inform the diagnostic process.

Trigeminal-mediated headshaking is the most recognized form, involving neuropathic sensitization of the trigeminal nerve. Management includes nose nets, UV-blocking masks, cyproheptadine, carbamazepine, and in select cases percutaneous electrical nerve stimulation, tailored to severity and seasonality.

A standard neurologic examination assesses mentation, cranial nerves, gait and posture, proprioceptive positioning, and segmental reflexes. Grading systems help localize the lesion and monitor progression or treatment response over time.

Cervical radiography, myelography, MRI, and CT are considered when spinal cord compression, intracranial disease, or vertebral malformation is suspected. Imaging selection depends on lesion localization, availability, and whether the horse can safely undergo general anesthesia.

Prognosis varies widely depending on the diagnosis, severity, and duration of signs. Many horses with EPM improve with treatment, while those with severe spinal cord compression or viral myeloencephalopathy may face limited recovery, guarded prognosis, or ongoing management needs.