Forty-two states were tracing and testing horses that may have been exposed to contagious equine metritis as of mid-January. So far, 383 horses had been exposed, according to the Department of Agriculture.
This highly contagious disease can be transmitted during breeding or artificial insemination and can cause temporary infertility of horses. The disease, not known to affect humans, was last detected in the United States nearly 30 years ago.
The outbreak began in mid-December 2008 when CEM infection was detected in a Quarter Horse stallion in Kentucky during routine testing of an international semen shipment. The USDA and Kentucky animal health authorities quickly started an epidemiologic investigation, leading to the testing of more horses. They found eight more infected stallions: three in Kentucky, three in Indiana, one in Wisconsin, and one in Texas. The Indiana and Texas stallions spent part of the 2008 breeding season on the Kentucky location where the initial CEM case was detected.
In addition to the nine stallions, the USDA says locations of 374 exposed horses have been confirmed as of Jan. 23. Those 383 horses comprise 51 stallions and 332 mares located in 39 states. The 51 test-positive or exposed stallions are located in 12 of those states, and the 291 exposed mares are in 39 states. There are 97 additional exposed mares and one stallion still actively being traced.
All located horses are under quarantine or hold order. Testing and, when appropriate, treatment protocols were being put into action for them as well by state animal health authorities.
Dr. Linda Mittel of Cornell University College of Veterinary Medicine's New York State Animal Health Diagnostic Center said strict hygiene should be followed whenever handling breeding mares or stallions to prevent reproductive infectious diseases, including CEM. Dr. Mittel said the following recommendations can assist in preventing the spread of reproductive infectious diseases.
- Wear disposable examination gloves when working with the genitalia of breeding mares, foaling mares, tease stallions, or breeding stallions.
- Use alcohol-based hand sanitizers or wash hands with soap and water between each examination if disposable gloves are not available.
- Use disposable supplies whenever possible and discard between each examination. This includes examination gloves, rectal gloves, vaginal speculums, tails wraps, practical cotton for washing, and artificial insemination supplies.
- Disinfect or sterilize (with steam or gas) nondisposable equipment between examinations such as Bivona tubes, uterine lavage systems, embryo transfer collections units, and surgical instruments.
- Cover ultrasound probes with an equine rectal sleeve. Any equipment that cannot be washed or autoclaved/sterilized should be thoroughly cleaned and disinfected with an antiseptic or alcohol.
- Line any buckets used for washing or cleaning the genitalia of mares or stallions with disposable plastic garbage bags. Change between examinations and discard used liners in appropriate garbage containers.
- Wear gloves for postfoaling examinations of mares, placenta, and aborted fetuses.
- Keep placentas and aborted fetuses from other horses, domestic animals, and wildlife.
CEM cases or suspect cases should be reported to the USDA or state animal health officials at www.usaha.org/StateAnimalHealthOfficials.pdf (PDF, 81 Kb).
For more information regarding CEM, visit www.aphis.usda.gov and click on the contagious equine metritis item under "Hot Issues."