AUGUSTA — State officials warned horse owners and breeders Wednesday about a serious disease potential after seven mares in Maine were exposed to contagious equine metritis, or CEM, a venereal disease of horses.
State Veterinarian Don Hoenig said Wednesday that 10 stallions outside Maine have tested positive for CEM and have potentially exposed hundreds of other horses to the disease.
He said CEM can be spread when horses are bred, or congenitally from mares to their foals. While natural breeding is more likely to spread the infection, Hoenig said, horses involved in artificial breeding also can be exposed to CEM.
“In addition to the seven mares in Maine, there are approximately 443 other potentially exposed horses in 45 other states,” Hoenig said. “As potentially exposed horses are identified, they are placed under strict restrictions by state and federal animal health authorities, pending three consecutive negative test results and subsequent treatment.”
Hoenig said the state Agriculture Department and U.S. Department of Agriculture veterinarians have quarantined the seven exposed Maine mares and have begun testing. “At this time, none of the potentially exposed Maine mares, nor those in other states, have tested positive for CEM,” he said.
Hoenig did not identify the locations of the quarantined horses, or whether they came from one farm or more. The most recent New England Agriculture Statistics estimates that Maine has a horse population of 17,000.
Dr. Robert Causey of the University of Maine, an equine reproduction expert, said none of the university’s horses is affected.
“This notice is very important,” he said. “Breeders and horse owners need to know this disease is in the background.” Causey said a random case, most likely spread from horses imported from Europe, pops up once every few years. “Everybody should be paying attention and being a little bit more careful.”
The CEM-positive stallion suspected of exposing the Maine mares is a 9-year-old Friesian named Nanning 374 and is stabled in Wisconsin.
Infected stallions seldom, if ever, show outward signs of infection, but may act as carriers of the disease, Hoenig said. CEM may render mares infertile or may cause horses to spontaneously abort; however, the disease can be treated with antibiotics and disinfectants. There is no evidence that CEM affects humans.
The first confirmed case in this current outbreak was traced to a single quarter horse stallion in Kentucky that was confirmed positive for CEM last December, according to USDA. Since then, 10 stallions have been confirmed as positive for CEM by USDA’s National Veterinary Services Laboratories.
The infected stallions are located in four states: three in Indiana, four in Kentucky, one in Texas and two in Wisconsin.
Horse owners and breeders seeking more information on the Maine situation should call the state Department of Agriculture at 287-3701 to speak with either Hoenig or Dr. Beth McEvoy.