• horse;
  • neurological disease;
  • verminous encephalitis;
  • migrating parasites


Verminous myeloencephalitis is a rare, but predominately fatal, cause of neurological disease in horses. A 6-year-old mare was admitted to the Royal Veterinary College Equine Referral Hospital following acute onset of depression, central unilateral blindness and compromised vision in the opposite eye. Based on pronounced eosinophilic inflammation detected in the cerebrospinal fluid (CSF) and diagnostic imaging findings indicating a space-occupying lesion within the brain, a presumptive diagnosis of aberrant parasitic migration causing parasitic encephalitis was made. Treatment consisted of anti-inflammatories and high doses of an anthelmintic. The horse's condition improved, the neurological deficits and observed space-occupying lesion within the brain resolved completely and the mare returned to full work. To the authors’ knowledge, this is the first report describing complete recovery from suspected aberrant parasite migration in the CNS and will hopefully encourage treatment of suspected cases in the future.