Outbreak of neurologic disease caused by equine herpesvirus-1 at a university equestrian center.
BACKGROUND
Equine herpesvirus type 1 (EHV-1) infection causes neurologic disease in horses. However, risk factors for the disease and long-term prognosis are poorly characterized.


OBJECTIVE
There are identifiable risk factors for equine herpes-1 myeloencephalopathy.


METHODS
The entire population of 135 horses housed within the equestrian facility.


METHODS
A descriptive study investigated the clinical, serologic, virologic, and management aspects of an outbreak of EHV-1 myeloencephalopathy.


RESULTS
Out of 135 horses at the facility, 117 displayed signs of EHV-1 infection. Forty-six horses developed neurologic deficits characterized by symmetrical hind limb ataxia and weakness. Twelve horses that developed neurologic deficits became recumbent and did not survive. The development of severe neurologic deficits during the outbreak was associated with the presence of residual deficits at the 6-month examination. Within 1 year of the outbreak onset, all horses that survived had returned to an exercise level comparable to that experienced before the outbreak. Factors associated with the development of neurologic disease included age of > 5 years, location in the south or arena stall areas, and highest rectal temperature on day 3 or later of the febrile period.


CONCLUSIONS
Being > 5 years of age, having had a rectal temperature of > 103.5 degrees F, and highest rectal temperature occurring on or after the 3rd day of the febrile period were the factors most predictive of the development of neurologic disease and death. Data obtained during this outbreak substantiate previous findings relating to clinical aspects and diagnosis of EHV-1 myeloencephalopathy. The prophylactic and therapeutic use of acyclovir during this outbreak is described.
Henninger
Rick W
RW
University Equine Veterinary Services, Findlay, OH 45840, USA. henninger@findlay.edu
Reed
Stephen M
SM
Saville
William J
WJ
Allen
George P
GP
Hass
Gregory F
GF
Kohn
Catherine W
CW
Sofaly
Cheryl
C
D000212:Acyclovir / Q000627:therapeutic use; D018712:Analgesics, Non-Narcotic / Q000627:therapeutic use; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use; D000998:Antiviral Agents / Q000627:therapeutic use; D002493:Central Nervous System Diseases / Q000662:veterinary*; D003002:Clonixin / Q000031:analogs & derivatives / Q000627:therapeutic use; D003907:Dexamethasone / Q000627:therapeutic use; D004121:Dimethyl Sulfoxide / Q000627:therapeutic use; D004196:Disease Outbreaks / Q000662:veterinary*; D005260:Female; D006566:Herpesviridae Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D004861:Herpesvirus 1, Equid / Q000302:isolation & purification*; D006734:Horse Diseases / Q000453:epidemiology / Q000821:virology*; D006736:Horses; D008297:Male; D010653:Phenylbutazone / Q000627:therapeutic use
D018712:Analgesics, Non-Narcotic; D000893:Anti-Inflammatory Agents; D000998:Antiviral Agents; D003907:Dexamethasone; C014558:flunixin meglumine; D010653:Phenylbutazone; D003002:Clonixin; D000212:Acyclovir; D004121:Dimethyl Sulfoxide