Antimicrobial Resistance in Equine Reproduction Discussed at 2024 AAEP Convention

Mats Troedsson, a veterinary specialist from the University of Kentucky’s Maxwell H. Gluck Equine Research Center, addressed the issue of antimicrobial resistance during a presentation at the 2024 American Association of Equine Practitioners Convention in Orlando, Florida. The focus was on the use of antibiotics in theriogenology, particularly for improving reproductive efficiency in horses, even in the absence of infections. Antibiotics are often administered during procedures such as post-breeding infusions, embryo transfers, and in semen extenders without any confirmed infection.

Troedsson highlighted that breeding-induced endometritis is primarily caused by sperm, rather than bacteria, aiming to create a suitable environment for embryo survival. Recent findings indicated that around 30% of mares can resolve inflammation in the uterus within six hours after breeding, with approximately 85% of broodmares showing resistance to persistent endometritis. Troedsson emphasized the efficiency of the uterine defense mechanisms in most mares. For those unable to clear this inflammation, he pointed out potential underlying factors, such as poor response to inflammation and conformation issues. In situations where bacteria remain in the uterus, the appropriate antibiotics should be based on culture results, and treatments may last three to five days, potentially combined with uterine lavage if needed. He also discussed challenges like bacteria in deeper endometrial layers or biofilm formations, which complicate treatment.

Troedsson introduced a sterile growth medium called bActivate, which can reactivate dormant bacteria for culture testing. He warned that biofilms can lead to antibiotic resistance and must be diagnosed accurately to inform treatment options. He advocated for alternative treatments for breeding-induced endometritis, cautioning against routine antibiotic use, suggesting instead to consider other methods such as immune modulators and ecbolics. Troedsson concluded by stressing the importance of using scientific data to guide treatment decisions in equine reproductive health and the need for alternatives to antibiotics in the absence of confirmed infections. Individuals seeking horse health information are advised to consult qualified veterinarians for guidance on diagnosis and treatment.