Contagious Equine Metritis Investigation Progresses in Wisconsin

Veterinary authorities continue to connect the dots in the investigation into contagious equine metritis (CEM), a contagious venereal disease of horses. Earlier this week, officials announced that an imported Friesian stallion in Wisconsin tested positive for the causative bacterium, Taylorella equigenitalis, perhaps bringing them closer to understanding how this disease--which hadn't been found in the United States' native equine population for nearly 30 years--suddenly popped up.

The Friesian stallion, now identified as Nanning 374, was imported to the United States from The Netherlands in late 2004, leaving quarantine in January 2005. He resided in California until October 2006, at which time he relocated to Wisconsin, according to owner Scott Kelnhofer of Hortonville, Wis.

The investigation headed his way when one of the Paint stallions found positive for CEM in Indiana was linked to Nanning 374 during the 2007 breeding season. After the Paint left Wisconsin, he stood at the Kentucky index farm, DeGraff Stables/Liberty Farm Equine Reproduction Center LLC, in 2008, before he was shipped to Indiana.

"This evidence strongly suggests and certainly supports a conclusion that the source of introduction of the bacteria to Kentucky has been identified," said Rusty Ford, equine programs manager in the office of Kentucky State Veterinarian Robert Stout, DVM. "And though that is our opinion today, our disease investigations continue with all other potential sources of introduction continuing to be tested in order to identify the true source of introduction of this disease to Kentucky, as well as all possible opportunities of spread."

Ford reiterated that they are conducting extensive investigations in both directions--backward to discover the source of the bacterium, and forward to investigate all opportunities for transmission.

In Wisconsin, Katherine Fox, DVM, of Equine Unlimited LLC, in New London, Wis., where Nanning 374 was collected for artificial insemination, is working with clients and the state to test other stallions that came through the facility in 2007 and 2008.

Fox explained that the practice is not a stallion station--they train stallions to mount and collect from stallions that are otherwise maintained at home. She said the vast majority of the stallions involved in the area investigation are being tested and treated at home through coordination with the state veterinarian.

"The state people have been great, and we're pushing through this," Fox said. "I have found everybody to be very helpful. They're walking everybody through it, and it's a good, cooperative team effort."

"I really encourage everybody to approach this with a spirit of working together, solving this, and really just tending to business at hand."
--Dr. Katherine Fox
Wisconsin State Veterinarian Robert Ehlenfeldt, DVM, said the state is investigating 19 stallions, some of which trace through Equine Unlimited, while others were potentially exposed via the Kentucky cases. They are also looking at 23 mares, which he said are primarily Kentucky exposures.

According to the USDA, the overall investigation includes 334 exposed horses, made up of 43 stallions and 291 mares, which are located in 39 states. Nine stallions (including Nanning 374, four in Kentucky, three in Indiana, and one in Texas) have so far tested positive.

"I really encourage everybody to approach this with a spirit of working together, solving this, and really just tending to business at hand," Fox said. "This is something that has befallen a lot of us, and it's nobody's fault."

Kelnhofer said Nanning 374 has never performed live cover and has never inseminated mares outside the Friesian breed. Kelnhofer had been contacted with the news that his stallion had to be tested after the Indiana Paint came up positive. Nanning 374's positive result came as a complete surprise.

Mare CEM video

Watch the CEM testing and treatment protocol for mares and stallions.

"We were contacted by our vet and the state vet in regard to the situation," Kelnhofer said. "I was upset over the fact that they were going to have to go through the testing, because I was confident that we were going to come up negative. And I was very concerned about him live covering the mares during the course of the finalization of the testing because of the possibility of injury, and I didn't want to expose him to that."

After coming up positive on preliminary culture, Nanning 374 has completed three rounds of treatment. He will be bred to two CEM-negative test mares if his cultures remain negative after a designated waiting period.

The Kelnhofers have provided a list of their clients to investigators, and mare owners are being contacted to notify them of the need to test.

Back in Kentucky, the identification of Nanning 374 as a player in the investigation brings a sigh of relief for those in the state's signature Thoroughbred industry, poised on the verge of breeding season.

"Having now indentified the probable source of this outbreak, there continues to be no evidence or suggestion that the disease had any opportunity of introduction to our Thoroughbred populations, and we anticipate an uneventful Thoroughbred foaling year and breeding season," Ford stated.

While Nanning 374 might provide a large piece in the investigational puzzle, the overall image remains far from complete. Tracing, testing, and treatment continue.

Watch for updates to this continuing situation.

About the Author

Erin Ryder

Erin Ryder is a former news editor of The Horse: Your Guide To Equine Health Care.

Stay on top of the most recent Horse Health news with FREE weekly newsletters from Learn More