Contagious equine metritis: a review.

This research article provides a comprehensive review of Contagious Equine Metritis (CEM), a highly infectious horse venereal disease caused by a fastidious Gram-negative coccobacillus and which affects breeding outcomes. The paper discusses disease symptoms, transmission, geographical impact and challenges in disease control.

Understanding Contagious Equine Metritis (CEM)

• CEM is a sexually transmitted disease in horses caused by a specific type of bacterium referred to as fastidious Gram-negative coccobacillus. This bacterium requires specific conditions for growth; it thrives best in an environment with 5-10% carbon dioxide and prefers a growth medium known as chocolate agar.
• The disease manifests clinically as a watery to mucopurulent vaginal discharge, typically observed around two to ten days post-mating with an infected stallion. In essence, this means that affected mares could display a range of discharge, from clear and watery to thick and pus-like, after breeding with a carrier stallion.
• In many cases, shortened estrous cycle lengths may be common. This refers to a decrease in the regular timing between each estrous or ‘heat’ cycle in the mare. In certain instances, this might be the only significant symptom of an underlying endometritis, an inflammation of the inner lining of the uterus.

Challenges in Disease Control

• A significant challenge in managing CEM involves the existence of inapparent carriers of the disease. These are horses which carry and can spread the disease, but do not display any obvious clinical signs themselves. Both mares and stallions can be inapparent carriers, which adds an extra layer of complexity to disease control.

Geographical Impact

• CEM has a notable geographical spread. Outbreaks have been reported across multiple countries and continents, including England, Ireland, France, Australia, and the United States. This highlights the global nature of the disease and underscores the necessity for international cooperation and standardization of testing and control measures.

Review of Current Information

• The article provides a thorough review of the existing information on CEM. It consolidates the current understanding of the disease’s clinical manifestations, the bacterium causing the disease, and known challenges with disease control. This review helps practitioners, researchers, and policy-makers have the most up-to-date and comprehensive understanding of CEM.