EHV Update: All’s Quiet in Maine, Quarantine Continues

Here’s the latest information from the Maine state government, after an EHV outbreak at a farm there recently:

AUGUSTA, MAINE?Over a 10-day period at the end of March, three horses died on a farm in Rome after exhibiting similar neurologic symptoms. Testing confirmed at least one of the horses had Equine Herpes Virus Type 1 (EHV-1), a contagious disease of horses, not transmitted to people. A fourth horse in Wales, housed for a short time at the farm in Rome, tested positive for EHV-1, but is recovering with continued treatment.

Horses at both farms are being carefully monitored, and quarantines will be in place for at least 21 days after the last clinical signs have resolved. It is likely that the Maine Department of Agriculture will require some form of EHV-1 testing before the quarantines will be released. EHV-1 is present throughout most of the world and almost all horses older than two years of age in the U.S. have been exposed.

The most common means of EHV-1 transmission is by direct contact with infected horses through aerosol transmission of droplets by coughing or snorting. Additionally, since the disease can also cause abortions, mares that have aborted can shed the virus through bodily fluids and the aborted fetus itself. Depending on the weather, the virus may persist in the environment for several weeks; viruses survive well in the cold, damp, and dark, but don’t survive long under hot, dry, sunny conditions. Inanimate objects, such as grooming tools, water and feed buckets, and contaminated clothing or footwear can also be potential sources of disease spread.

Therefore, all horse owners and people who conduct business on horse farms (feed trucks, farriers, veterinarians, sales people, etc.) should practice strict biosecurity. This includes changing coveralls when traveling between farms, cleaning and disinfecting all equipment used when treating or handling horses, and cleaning and disinfecting footwear or boots between farms. An excellent and cheap disinfectant solution can be made by adding five tablespoons of household bleach per one gallon of water. This should only be used after surfaces have first been thoroughly cleaned of all organic matter and dirt.

State Veterinarian Don Hoenig, says “We recommend careful evaluation and consultation with your veterinarian in deciding whether to continue to hold or participate in events such as shows, races, training courses, trail rides, and other gatherings of horses. Each case is unique and there is no one-size-fits-all approach.”

The Department of Agriculture, in consultation with Maine veterinarians and equine professionals, recommends that all fairs, racetracks and training facilities require EHV-1 vaccination, not less than 14 days or more than six months, before entering their facilities. “While we realize that the role of the vaccine in preventing the neurologic form of EHV-1 is controversial, we nevertheless feel that vaccinating is a prudent measure at this time. Other states in the region have made similar recommendations. Your veterinarian can consult with you further on the specific type and timing of the vaccine,” added Hoenig.

Contact Don Hoenig with any questions at 207-287-7615. More information can also be found on the state Web site at:




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