The association between the endometrial biopsy grade and selected epidemiological and reproductive variables in a population of subfertile mares

Abstract

BACKGROUND : Endometrosis, a multifactorial disease, is an important cause of subfertility in the mare, and its management is reliant on histological classification. OBJECTIVES : This study aimed to determine the association between increased endometrial biopsy grade with first a mare's breed specifically either Thoroughbred or non-Thoroughbred, age and barren status and second, a clinical history indicating one or more of acute endometritis, positive bacterial culture, previous dystocia and uterine fluid retention. STUDY DESIGN : Retrospective case series. METHODS : This retrospective study used historical reproductive data (2000–2015) from a population of 41 subfertile mares of various breeds, but mostly Thoroughbreds (30/41; 73%). Biopsies were interpreted by a single, experienced evaluator using the Kenney–Doig classification (1986). RESULTS : Endometrial biopsy grade was positively correlated with age (ρ = 0.606; p = 0.001) but not associated with other evaluated variables (p > 0.05). MAIN LIMITATIONS : Use of a small, non-randomly selected subfertile mare population. CONCLUSIONS : Mare age was an important predictor of her reproductive performance, and performing an endometrial biopsy is therefore indicated in older mares.