Prognostic value of endometrial biopsy in the mare: a retrospective analysis.

A retrospective analysis was made of 79 endometrial biopsy specimens obtained from mares with histories of infertility. The specimens were classified into 3 standard prognostic categories, according to the severity of the histologic changes. The 36 mares that had few endometrial lesions (category I) had a foaling rate of 78%. The 29 mares that had more severe endometrial changes (category II) had a foaling rate of 55%. The 14 mares with the most severe endometrial lesions (category III) had a foaling rate of 35%. The pregnancy losses for each category were 9.7%, 23.8%, and 44.4%, respectively. It was concluded that uterine biopsy can be a useful aid in predicting fecundity in the mare when it is used in conjunction with evaluation of the history, clinical examination, and appropriate diagnostic laboratory tests, but only if satisfactory biopsy specimens are obtained and examined by an individual who has the experience and training to interpret the lesions.