Effects of Intrauterine Infusion of a Water-Based Suspension of Enrofloxacin on Mare Endometrium

Intrauterine infusion of a commercial preparation of enrofloxacin has been shown to produce severe inflammation and irreversible deterioration of endometrial biopsy scores in mares. The aim of the present work was to evaluate the effect of intrauterine infusion of a water-based enrofloxacin suspension on mare reproductive tracts. Eight systemically healthy mares were used in the experiment. Each mare underwent a complete reproductive evaluation (ultrasonography, vaginal examination, endometrial cytology, endometrial culture, and endometrial biopsy) before treatment. Each mare received an infusion of 50 mL of a 2.5% water-based suspension of enrofloxacin daily for 3 days. To evaluate the acute effect of treatment, mares were examined daily by transrectal ultrasonography and vaginoscopy during the treatment and an endometrial biopsy was obtained 24 hours after the final infusion. To evaluate the chronic effect of treatment, a complete reproductive evaluation was performed on mares 21 days after initiation of treatment. Results of clinical evaluation showed a significant increase in intrauterine fluid accumulation during the treatment. A nonsignificant increase in endometrial biopsy grade was observed after the 3 days of treatment. There was no long-lasting effect of the infusion on clinical evaluation or endometrial histology. Endometrial concentrations of enrofloxacin and its metabolite ciprofloxacin were highly variable among mares yet were above the minimum inhibitory concentration in four of eight treated mares. We conclude that intrauterine infusion of a water-based enrofloxacin solution produced only a transient inflammatory response and may be useful for the treatment of bacterial endometritis sensitive to enrofloxacin without the deleterious effects seen with the administration of the commercial preparation.