<b>Preliminary investigation of the effect of intra-uterine vinegar lavage on endometrial biopsy scores</b>

Background: The addition of compounds, such as acetic acid (vinegar) to lavage fluids may improve outcomes in treatment of endometritis. A previous study found that infusion of a dilute vinegar solution into the uterus was associated with decreased inflammation, suggesting a direct, beneficial effect may also exist. However, studies often fail to include a positive control groupObjectives: To observe the effect of intra-uterine lavage with a dilute vinegar solution on endometrial biopsy scores when compared with a saline control in a population of mares during the breeding seasonStudy design: randomised, controlled experimental studyMethods: Twelve Standardbred and Warmblood mares (4-18 years old) were paired by similar age group and pre-treatment endometrial biopsy scores and randomly assigned to either the Control group or the Vinegar group. Intrauterine lavage with 1L of sterile saline (Control group) or 20mL of vinegar in 1L of sterile saline (Vinegar group) was performed daily for 3 consecutive days during oestrus or until ovulation had occurred (whichever occurred first). Treatment was repeated in the subsequent oestrous cycle. Endometrial biopsy was repeated once all mares had completed treatment. Both pre- and post-treatment biopsies were scored and graded using the Kenney-Doig score and a modified scoring system. Linear regression modelling was used for analysis of results.Results: There was no statistical difference between treatment groups.Main limitations: Small sample size (n=12), oestrus period overlapped with treatment period, number of treatments varied between mares.Conclusions: Uterine lavage with saline or vinegar in saline had no direct effect on the endometrium biopsy scores of the mares in this study.