Contagious equine metritis (CEM) is an extremely contagious venereal disease that is acquired primarily via breeding.

While this disease can be carried by either mares or stallions, it is the mare that suffers the ill effects of the infection. Stallions do not show any symptoms of CEM, but mares often will have a thick discharge from the vagina, and will be unable to conceive during the point at which the infection is active.

This is generally a non-lethal disease, and even if left untreated, the mare’s system will typically clear the infection on its own over a few weeks time. Blood tests can identify the infection, but it may only indicate that the mare has had the infection, and not whether the infection is still active.

CEM is a bacterial disease caused by Taylorella equigenitalis, and can be treated with antibacterial washes, which is recommended.

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CEM Screening

Please Note:

  • The tests can only be done by a veterinarian.
  • No coverage after 31 August 2011 can be accepted by the Society without a CEM exemption certificate for a stallion.
  • This applies to both natural coverage and Artificial Insemination.
  • It is now an yearly tradition that all stallions should be tested from 1 July to 31 September for the breeding season.
  • This will continue to be an yearly tradition until South Africa is declared free of CEM.
  • The cost of the tests will be on each person’s own account.
  • If the stallion dies before he could be tested, the mare and the foal must be tested.

Cost of the tests are R400 per horse ( two tests ) and for each person’s own account.

For inquiries regarding your CEM Certificate, please contact Genie at 012 529 8068

To confirm whether a stallion has a CEM-exemption certificate, please visit the following website

See also the letter below in which Dr. G Aldrich asked questions about the matter, and the responses received to his questions.