Herpesvirus myeloencephalopathy in horses: 11 cases (1982-1996)

To determine results of CSF analysis in horses with equid herpesvirus myeloencephalopathy (EHM) and to determine whether results of CSF analysis were associated with outcome.

Retrospective study.

11 horses.

Medical records of all horses admitted to the veterinary teaching hospital between February 1982 and March 1996 in which EHM was diagnosed were reviewed.

7 horses were < or = 4 years old; 8 were admitted during January, February, or March. Six horses were febrile prior to admission, but none was febrile on the day of admission. Five horses had been stabled with other horses that had clinical signs of neurologic disease. All horses had had an acute onset of hind limb ataxia and paresis. Cranial nerve deficits were detected in 3 horses. Cerebrospinal fluid samples were collected on the day of admission from 10 horses. Protein concentration was high in 8 horses; nucleated cell count was normal in 8. Protein concentration and nucleated cell and RBC counts were not significantly different between horses that survived and horses that were euthanatized. Six horses were euthanatized, and 5 survived. All of the horses that survived remained standing or were able to stand with minimal assistance.

High CSF protein concentration and normal or only slightly high CSF nucleated cell count are common in horses with EHM; however, results of CSF analysis were not associated with outcome. Horses with EHM that become recumbent have a poor prognosis for survival.