CEM: Testing Continues, Officials Tracking Mares

Following the Dec. 19 announcement that two additional stallions have cultured positive for contagious equine metritis (CEM) on a Central Kentucky breeding facility, authorities now have the challenge of not only determining the status of the farm's other resident and removed stallions, but also the mares they've covered, in an investigation that has the potential to include dozens of other states.


Watch a video interview on contagious equine metritis with Dr. Peter Timoney of the University of Kentucky.
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CEM is a highly contagious venereal infection that can cause infertility and abortions, or can exist and spread subclinically. While it exists, or has been known to exist, in the native equid populations in 25 countries around the world, the United States is considered free of this disease. Read more about CEM.  

According to the statement released by the Kentucky Department of Agriculture (KDA), infected stallions now include a 13-year-old Quarter Horse and a 4-year-old Paint. The first recognized case, a 16-year-old Quarter Horse, tested positive on Dec. 10. The affected stallions and all exposed horses that remained on the farm have been quarantined. In total, 22 stallions had been at the breeding facility during the 2008 season, after which all but eight of the stallions shipped to other farms.

Aside from the three positives, the other five stallions remaining on the farm have tested negative on culture, but since Taylorella equigenitalis, the causative organism, is slow to grow, the diagnostic process continues. The lengthy process includes breedings to CEM-negative test mares to see if they transmit the organism. According to Rusty Ford, equine programs manager in the office of Kentucky State Veterinarian Robert Stout, DVM, a unified protocol for testing the at-risk stallions (those who were collected for breeding at the affected farm) and the exposed mares (those bred with semen from infected stallions) has been developed.

Ford said this protocol differs from the usual testing required when importing horses from CEM-affected countries. Because the animals involved in this situation are from an affected premises, on which disease transmission appears to have occurred, "we view these animals as posing a significantly higher probability of exposure and are therefore utilizing this more stringent testing," Ford said.

The issue goes beyond the identified stallions--testing and disease control measures must be extended to the mares that received semen from these stallions. The 13-year-old Quarter Horse, for example, bred around 50 mares, according to Ford.

"These mares are located in a number of states and the USDA is in the process of making notification to those states," Ford said.

Because of the numerous jurisdictions involved, the investigation is a joint effort between the Kentucky Department of Agriculture, the State Veterinarian's Office, and the USDA. Local resources, including the University of Kentucky's Livestock Disease Diagnostic Center, have also played a key role, Ford said.

Kentucky Agriculture Commissioner Richie Farmer and Governor Stave Beshear have discussed the matter, according to the KDA statement. Additionally, Commissioner Farmer has asked U.S. Agriculture Secretary Ed Schafer to declare a state of agricultural emergency and commit federal funds for the investigation.

At this time, the epidemiological investigation has not revealed any link to the Thoroughbred industry, which is preparing for the upcoming breeding season. Kentucky's horse industry has a total estimated economic impact of approximately $5 billion a year. The horse industry generates an estimated 80,000-100,000 jobs, and another 14,000 jobs come from tourism businesses related to the horse industry. Kentucky farm cash receipts for equine, including stud fees, are estimated at $1 billion annually.

"It is important for the people of Kentucky to understand that this could be a serious situation in our signature equine industry," Commissioner Farmer said in the statement. "The state is working with federal authorities to contain the outbreak and determine its source."

Keep an eye on TheHorse.com for further updates as the situation continues to develop. Read more about CEM.

About the Author

Erin Ryder

Erin Ryder is a former news editor of The Horse: Your Guide To Equine Health Care. She owns a portly gray gelding named Duncan and dabbles in several equestrian disciplines, with an emphasis on dressage.

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