Disease factsheet: Contagious Equine Metritis (CEM) - Questions & Answers
- What is Contagious Equine Metritis (CEM)?
- What causes CEMO?
- What are the clinical signs of the disease?
- How is the disease spread?
- Can the disease be treated?
- Will the identity of the affected horses or “at risk” horses be made public?
- What action has been taken in relation to the confirmed case of CEMO?
- What can I do to prevent my horses from catching the disease?
- How can the spread of infection be stopped?
- Is there any risk to human health?
- Will there be any effect on international trade?
What is Contagious Equine Metritis (CEM)?
A. CEM is a contagious venereally-transmitted bacterial disease of the horse family. It causes epidemic subfertility and is a notifiable disease. This means that suspected cases of CEMO must be notified to a Divisional Veterinary Manager (DVM) of Animal Health. It can result in serious disruption to breeding operations.
What causes CEMO?
A. The bacterium recognised as causing outbreaks of CEMO is Taylorella equigenitalis (the Contagious Equine Metritis Organism, CEMO). There are two strains, both capable of producing epidemic venereal disease in susceptible mare populations.
What are the clinical signs of the disease?
A. In the mare the severity of disease caused by the CEMO organism varies. The main outward clinical sign is a mild to heavy discharge from the vulva, resulting from an inflammation of the uterus (endometritis). Occasionally mares will show no clinical signs. Whilst infected most mares will fail to conceive. There have been cases of abortion associated with CEMO. The incubation period is 2-12 days and the period of clinical infection lasts on average 2 weeks. Infected stallions do not usually show clinical signs of infection, but merely harbour the organism on their external genitalia. Further details are available online or on the Horserace Betting Levy Board’s website.
How is the disease spread?
A. Infection spreads through direct venereal transmission of bacteria from mare or teaser mare to stallions, or from stallion or teaser stallion to mares at the time of mating or teasing. It can also be transmitted to mares if semen used in artificial insemination (AI) comes from infected stallions. Indirect infection can also occur, through contaminated water or utensils (eg. vaginal speculums, examination gloves etc). Spread can occur by personnel failing to observe adequate hygienic precautions in handling mares and stallions at time of breeding.
Can the disease be treated?
A. Yes, under the direction of a Veterinary Surgeon. After the treatment regime is completed, repeat swabs must be negative on at least three separate specified occasions under the direction of a Veterinary Surgeon.
Will the identity of the affected horses or “at risk” horses be made public?
A. We cannot disclose the names of the affected or any identified “at risk” horses or details of their owners without breaching the Data Protection Act and the law of confidentiality.
What action has been taken in relation to the confirmed case of CEMO?
A. The State Veterinary Service has investigated the case and statutory restrictions under the Infectious Diseases of Horses Order 1987 have been imposed on the premises where the affected horse is being held. Movement restrictions will remain on the affected horse until treatment has been completed and final tests for CEMO have proved negative.
What can I do to prevent my horses from catching the disease?
A. Detailed recommendations on the prevention and control of infection can be found in the Horserace Betting Levy Board’s Code of Practice on CEMO. Details are available online or on the Horserace Betting Levy Board’s website.
How can the spread of infection be stopped?
A. The main ways of stopping the spread of infection are:
- Adherence to the Horserace Betting Levy Board's Code of Practice for CEMO
- Pre-breeding tests
- Stopping mating by infected horses;
- Treatment of the infection and re-swabbing to check that the infection has cleared up before resuming mating (seek the advice of your veterinary surgeon on swabbing);
- Exercising strict hygiene measures when handling the horses involved.
- Ensuring that semen used in AI has been taken from stallions with CEMO negative swabs.
Is there any risk to human health?
A. No
Will there be any effect on international trade?
A. There are no CEM related certification requirements for the movement of horses from the UK to other EU Member States. Most third country destinations do not insist on CEM country freedom as a prerequisite for export and rely on pre and post export testing. India however requires exporting countries to be CEM free for 3 years before allowing imports of breeding animals.
Page last modified:
August 28, 2008