EHV-1 KILLS MICHIGAN RACEHORSE
Outbreak Feared, Steps Taken
By: John V. Wood

At least two horses at Northville Downs racetrack in Northville, MI have contracted equine
herpesvirus (EHV-1), one of which turned fatal. The potential outbreak was discovered
December 14, when a six-year old Standardbred gelding began exhibiting trademark
neurological signs. After the horse was taken to the Diagnostic Center for Population and
Animal Health at Michigan State University, it was diagnosed with equine herpesvirus myelitis,
attributed directly to
EHV-1.        
Dr. Elizabeth Carr DVM, assistant professor of large animal clinical sciences at MSU, treated
the infected Standardbred when it arrived on campus. “When the horse arrived, he was
dripping urine and his hind end seemed very unsteady. Those two things would be on your list
of differentials for equine herpesvirus,” said Dr. Carr. “Two of the more common clinical
presentations of EHV-1 are progressive weakness or ataxia (failure of muscle coordination)
that starts in the hind end and moves forward.” The infected horse was euthanized the very
next day.
Upon discovery of the possible outbreak, the track was quarantined and 25 horses have been
monitored very closely for telltale symptoms since that time. According to Dr. Steve Halstead
DVM MS, symptoms of EHV-1 include fever, cough, runny nose or neurological signs, and
typically appear within 21 days of potential exposure. The Michigan Office of Racing
Commissioner and the State Department of Agriculture are coordinating both the investigation
of the potential outbreak, and the monitoring of the quarantined horses.  Another horse at the
racetrack tested positive for EHV-1 on December 20.
EHV-1 is not necessarily fatal, and Dr. Carr says treatment is possible. “Signs can progress
pretty rapidly, but there are two stages of possible treatment. Supportive care can be used at
the onset of symptoms, then moving onto treatment with antiviral and/or anti-inflammatory
medications,” said Dr. Carr. “Complications, however, are likely if the horse is recumbent
(lying, unable to stand). If the horse can stand, then it has better chance of recovery.”
Officials say Northville Downs remains open for the conduct of live and simulcast horse racing.
Horse owners with questions should contact the Michigan Office of Racing Commissioner at
734-462-2400, or the Michigan Department of Agriculture's State Veterinarian Office at 517-
373-1077.





Sources:
*Dr. Elizabeth Carr, DVM MS, Equine Medicine, School of Veterinary Medicine, Michigan State
University, G319 Vet Medical Center East, East Lansing MI 48824-1314. (517) 355-3811.
carreliz@cvm.msu.edu

*Dr. Steve Halstead, State Veterinarian, Animal Industry Division Director, Michigan
Department of Agriculture. (517) 373-1077. halsteads@michigan.gov