CEM Exposure: Oklahoma Mare Quarantined

Oklahoma agriculture officials are warning horse breeders of contagious equine metritis (CEM), which can result in infertility in mares. One Oklahoma mare has been identified as having been in contact with an infected stallion.


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The mare is under quarantine and is not considered a health threat of any kind.

"This is a disease that poses no threat to humans but it could potentially pose a serious economic threat to our state's horse industry," said State Veterinarian Becky Brewer, DVM.

Infected stallions can carry the causative bacteria yet show no clinical signs of the disease. She said detecting the disease is difficult and requires multiple tests to determine if a horse is infected.

Infected horses can be successfully treated with antibiotics.

"The most important thing for Oklahoma horse breeders to know at this point is that the disease is here and biosecurity measures are critical," Brewer said. "We have no knowledge of any infected stallions in Oklahoma and owners should be cautious before shipping a mare out of state for breeding.

"Breeders collecting semen for artificial insemination should also make sure they thoroughly clean and disinfect collecting equipment after each use," she said.

More information is available on the USDA Web site.

As of Jan. 5, states that have announced they are testing exposed or at-risk horses include:
  • Kentucky
  • Indiana
  • North Dakota
  • Oklahoma
  • Texas
  • Virginia
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