Horse species symposium: contagious equine metritis: an insidious threat to the horse breeding industry in the United States.

The research article explores the impact of Contagious Equine Metritis (CEM), a sexually transmitted disease in horses, in the United States. It specifically highlights how the disease affects the horse-breeding industry.

Understanding Contagious Equine Metritis (CEM)

• The paper talks about CEM, a venereal disease in equids first recognized in 1977.
• The disease is caused by a previously unknown bacterium, Taylorella equigenitalis.
• The disease is primarily spread through sexual contact, and can cause short-term infertility in infected mares.
• Serious concerns within the equine industry arise from the fact that this bacterium can spread easily and the existence of a carrier state in both stallions and mares.

The History of CEM in the United States

• CEM’s first known outbreak in the U.S. was recorded in 1978 in Kentucky. The disease had a significant economic impact on the Thoroughbred industry of the state.
• Since then, small-scale outbreaks have been reported in 1979 in Missouri, 1982 in Kentucky again, and 2006 in Wisconsin. Most of these outbreaks were linked to the introduction of carrier animals into the U.S. horse population.
• Through diligent efforts to eradicate the infection, the U.S. was able to regain its CEM-free status each time, until the 2008 outbreak.

The 2008 CEM Outbreak

• In 2008, a Quarter horse stallion in Kentucky was found to be CEM-positive, marking the beginning of a significant outbreak.
• A comprehensive investigation revealed 23 carrier stallions and 5 carrier mares belonging to 11 breeds across 8 states.
• According to the paper’s findings, the spread of the bacterium was mainly attributed to transport of infected semen and indirect sexual contact in stallion collection centers due to contaminated equipment.
• Locking down the origin of this outbreak proved unsuccessful, despite investigations of over 1,000 possibly exposed or carrier animals across 48 states.

Implications and Future Concerns

• This research brings up questions regarding the cost-efficiency of investigating CEM occurrences, given that in most cases, infected or exposed mares did not show clinical evidence of the disease or decreased pregnancy rates.
• The article concludes implying that regaining a CEM-free status for the U.S. is increasingly challenging, especially as the scale of the outbreak and the number of potentially exposed animals rise.