Dimethyl sulfoxide intrauterine therapy in the mare: effects upon endometrial histological features and biopsy classification.

The effects upon equine endometrial histological features produced by 10 to 30% concentrations of dimethyl sulfoxide (DMSO) in sterile saline were compared with the effects of sterile saline (0.9% NaCl) alone as an intrauterine infusion therapy in 16 barren mares. No harmful histological changes were noted (P>0.05) as a result of the therapy. Thirty percent intrauterine DMSO therapy produced a significant (P<0.01) improvement (i.e., reduction of chronic inflammatory cell infiltrates and reduction of periglandular fibrosis) in endometrial biopsy classification in 18 of the 27 barren mares evaluated; whereas only 2 of 18 barren mares improved following intrauterine saline treatment in the control group. In subsequent breeding trials, the pregnancy rates following intrauterine therapy were no different between DMSO-treated mares and saline-treated control mares (P>0.05); however, there was a trend toward a higher pregnancy rate following DMSO therapy. The inability to control for sire variability in the breeding trials may have contributed toward the result that no significant difference could be demonstrated in the pregnancy rates between treated and control mares.