CEM - Contagious equine metritis

As economic globalization increases, disease can speedily spread among continents. One disease that severely affects breeding businesses domestically and internationally is contagious equine metritis (CEM).

Although CEM is found mainly in Europe, cases have recently been diagnosed in the U.S.—including within the Appaloosa and Quarter Horse breeds. CEM is curable and responds readily to treatment, though breeders and health officials are advised to take the disease very seriously.

Local veterinarians must report this sexually transmitted disease to state and federal area veterinarians when suspected or confirmed. CEM impacts breeders by restricting movement to and from affected breeding premises until the treated horses are confirmed free of the bacterium, Taylorella equigenitalis. Many countries have introduced strict import regulations to prevent its introduction into their horse populations.

Symptoms: Metritis is defined as inflammation of the womb, and symptoms in mares include temporary infertility even in the absence of visible signs. The incubation period is from two to 14 days, and some mares develop a vaginal discharge lasting a few days to two weeks within a week or two after breeding. However in some mares, the only sign may be a return to estrus heat after a shortened estrus cycle. Rarely, abortion occurs at about seven months gestation in the affected pregnant mare.

In stallions, CEM bacteria reside in the folds of the external genitalia, particularly the urethral fossa and its associated sinus. It’s largely undetectable without laboratory culture or by breeding to several test mares and culturing them.
Both mares and stallions may be asymptomatic carriers.

Diagnosis: Laboratory tests from swabs of the genital tract can detect T. equigenitalis in culture or through polymerase chain reaction (PCR). The organism is difficult to culture because other, faster-growing organisms obtained on the swab can obscure the slower-growing T. equigenitalis.

Treatment: In both the mare and the stallion, treatment includes a combination of scrubbing the external genitalia with an antiseptic such as Chlorhexidine, and applying antimicrobial ointment such as nitrofurazone or silvadene. In most cases, one round of treatment is effective but sometimes two or even three rounds are required.

Prevention: CEM spreads from mare to stallion or stallion to mare in two ways: during mating and through use of contaminated semen during artificial insemination. Isolation of stallions from mares, and treatment that’s confirmed successful by a veterinarian, effectively prevent the disease from spreading.

CEM can also spread congenitally via an infected mare to her foal. And, CEM can spread through contaminated breeding equipment, instruments or handlers, making fastidious breeding hygiene a necessity.