National Report — Investigators tracing a wide-ranging outbreak of contagious equine metritis (CEM) made important discoveries and took steps
to halt the infectious reproductive disease, but after nearly two months the origin remains elusive and quarantines and testings
Hygiene protocols for horse handlers
At press time, 10 stallions had tested positive in four states (two in Wisconsin, four in Kentucky, three in Indiana and one
in Texas) and were undergoing the standard treatment protocol.
Besides the 10 positive stallions, the locations of 433 exposed horses — 389 mares and 54 stallions — were confirmed in 45
states, and 65 CEM-exposed mares were still being traced, according to the US. Department of Agriculture's Animal and Plant
Health Inspection Service (APHIS).
An exposed horse is defined by APHIS as one that was on the index premises — in this case DeGraff Stables/Liberty Farm Equine
Reproduction Center LLC, Midway, Ky. — where the first positive stallion was identified in December, or one that was bred
to a CEM-positive horse, naturally or via artificial insemination.
One of the most recent and important findngs came in mid-January in Wisconsin, when a 13-year-old Friesian stallion that was
imported from the Netherlands in 2004 tested positive for Taylorella equigenitalis, the CEM causative bacterium.
Identified as Nanning 374, the stallion passed its importation quarantine in early 2005 and was in California until being
moved to Wisconsin in the fall of 2006. During the 2007 breeding season, Nanning 374 and one of the currently positive stallions
from Indiana went through the same artificial-insemination facility in Wisconsin, after which the Indiana stallion spent time
at the index premises in Kentucky. It then went to Indiana for the 2008 season. The Texas stallion also spent time at the
That's enough to conclude that the disease introduction into Kentucky, where the first positive in a Quarter Horse stallion
was reported Dec. 10, is now identified, says Rusty Ford, equine programs manager in the office of Robert Stout, DVM, Kentucky's
state veterinarian. Still, investigation and testings continue in Kentucky.
"It isn't likely anyone will ever know which horse was infected first. Did the Friesian infect the Indiana horse (perhaps
through the artificial-insemination equipment), or was it the other way around? It would take much more intensive detective
work, and even then it may never be known," says Donna Gilson, a spokesperson for Wisconsin's Department of Agriculture, Trade
and Consumer Protection.
"Investigators trace an outbreak backward and forward, but finding the original source is highly improbable," she says.
The owner of the Wisconsin artificial-insemination business and everyone else involved cooperated fully with Robert Ehlenfeldt,
DVM, Wisconsin's state veterinarian, who heads the Division of Animal Health, Gilson says.
"It's to everyone's advantage to cooperate. When the door to trade closes in one state, it closes in others, and no one wants
that to go on very long. Also, there's the cost factor," Gilson says, adding that Ehlenfeldt and his veterinary staff "have
a seamless relationship with the USDA. When a government vet comes to a farm, often the owner doesn't know if it's a state
or a federal vet."
In Kentucky, proactive steps taken at the index premises, along with timely communication with clients and state officials,
made for a smooth and effective investigation, Ford says.
The first positive was confirmed during routine testing prior to a semen shipment to Europe. Three more stallions on the Kentucky
property tested positive days later, as did three Indiana stallions that had spent time on the premises in 2008.