02/09/2025
Delighted to share another new publication available free open access in Equine Veterinary Journal. This time from a collaboration with Rossdales Laboratories, Camilla Scott, Billy Fehin, Mandi De Mestre and Juan Carlos Arango-Sabogal, through which we have published a series of papers describing the prevalence of bacterial isolates and antimicrobial resistance in endometrial swab samples, and evaluated the accuracy of cytology and culture to diagnose endometritis in Thoroughbred broodmares.
In this study we investigated associations between pre-breeding endometrial swab findings and live-foal rates, using data from over 7,500 endometrial swab samples submitted to the laboratory over 7 breeding seasons.
This is the first study to use multivariable modelling methods to investigate associations between endometrial swab findings and live-foal rates in Thoroughbred broodmares, identifying novel and important relationships.
Key findings:
🐎 In contrast to other categories of bacterial isolate, mares with a profuse growth of Escherichia coli had significantly lower live-foal rates compared to those with no growth.
🐎 There was interaction between mares' age and cytology.
🐎 In mares >12 years of age, significant reductions in live-foal rates were observed between mares with >30% PMN and mares with ≤0.5% PMN.
🐎 In mares ≤12 years of age, live-foal rates were not significantly different between categories of PMN ( ≤0.5% PMN; 0.5%–5% PMN; >5%–30% PMN; >30% PMN:endometrial cells per high power field).
Take home messages:
👉 In young mares, endometrial inflammation (% PMN) appears less likely to impact fertility outcomes and, therefore, beyond the ruling out of venereal transmissible infections, an endometrial culture and cytology may be of somewhat limited value in young, clinically normal individuals.
👉 Conversely, the value of identifying and instituting effective reproductive management around the time of breeding in mares >12 years of age with evidence of a marked endometrial inflammatory response and in mares with profuse E. coli cultures cannot be understated.
👉 Critically, and in contrast to previous studies, through the evaluation of endometrial bacteriology species and growth separately, our findings have refined current knowledge and identified an important subset of mares with a profuse growth of E. coli, in which important knowledge gaps exist around the aetiologies underlying their poorer fertility outcomes.
http://doi.org/10.1111/evj.70086