You’ve heard about it but what is it?

Contagious Equine Metritis was first discovered in England in 1978 and has scarily made its way to the United States. CEM is a highly contagious, sexually transmitted bacterial disease spread by infected stallions to mares during live cover, artificial insemination, or by using non sterilized gloves and instruments. CEM fatality has not been reported, however the effects can be devastating.

Stallions should be tested prior to the breeding season because they do not always exhibit signs of being infected with CEM. Infected stallions are usually passive carriers, meaning that they do not show clinical signs of infection but have bacteria within the flora of their external genital organs. If bred to an infected stallion, the mare may develop a discharge from the vulva, resulting from inflammation of the uterus. If a suspected infection occurs, she should be cultured.

The severity of the disease may vary:

	In the acute state: the mare has an active inflammation and obvious discharge that is seen 1-6 days after breeding.
	In the chronic state: the signs may be less obvious, but the infection is often deep seated and may be difficult to clear up. Discharge may not be seen for up to 80 days after breeding.
	In the carrier state: The bacterium is established within the bacterial flora of the genital area. Even though the mare is infected, she exhibits no signs and can pass the disease on.

CEM may prevent the mares from conceiving or cause them to abort. If the foal is carried to full term, it then becomes a carrier.