Equine Herpesvirus Neurological Disease

Equine herpesvirus myeloencephalopathy causes sudden neurological deficits in horses and requires urgent veterinary management and strict biosecurity to prevent outbreak spread.

Key Facts

EHM is a neurological complication of EHV-1 infection affecting the spinal cord and brain vasculature
Affected horses show ataxia, hindlimb weakness, and urinary incontinence varying in severity
Outbreaks at competition venues have affected hundreds of horses in single events
Most horses carry latent EHV-1 that can reactivate under stress, creating a persistent reservoir in equine populations
Treatment is supportive with anti-inflammatory drugs, anti-viral therapy, and intensive nursing care
Strict isolation of affected and contact horses is essential to prevent spread during outbreaks

Welfare Considerations

EHM causes acute neurological distress in affected horses through spinal cord and brain vasculitis. Severely affected horses experience rapid loss of hindlimb function, inability to urinate normally, and distressing neurological signs. Welfare management involves intensive nursing including bladder catheterisation in horses with urinary retention, anti-inflammatory management, and physical support for horses that are unable to maintain normal posture. Some horses recover substantially with treatment; others deteriorate to a point where euthanasia is the most humane option. Outbreak management through strict isolation prevents further welfare harm in at-risk contact horses.

What You Can Do

Isolate any horse showing neurological signs at a competition venue immediately and contact the vet
Follow outbreak biosecurity protocols including movement restrictions and hygiene measures
Ensure your horse EHV vaccination programme is up to date to reduce risk from respiratory EHV
Discuss EHV risk management with your vet if attending competitions or moving horses between yards
Support equine disease surveillance systems that enable rapid response to EHM outbreaks