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

Daily infusion of an alcohol-free water-based enrofloxacin suspension for 3 days does not appear to cause any permanent harmful changes to the endometrium and may be useful for treatment of endometritis due to enrofloxacin-sensitive bacteria. Authors’ addresses: Rood and Riddle Equine Hospital, PO Box 12070, Lexington, KY 40580-2070 (Schnobrich, Barber, Bradecamp); and Comparative Theriogenology, Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA 99164 (Pearson, Tibary); e-mail: mschnobrich@ roodandriddle.com.

1. Introduction

Bacterial endometritis is a common cause of low pregnancy and foaling rates. Many isolates are sensitive to enrofloxacin only. Intrauterine infusion of a commercial enrofloxacin preparation was associated with severe hemorrhagic inflammation and fibrosis in the endometrium. This study examines the effect of an alcohol-free water suspension of enrofloxacin^a after intrauterine administration.

2. Materials and Methods

Eight light-breed mares were used in the experiment. Each mare was administered a water-based suspension of enrofloxacin (2.5 mg/kg in 50 mL), in utero, daily for 3 days during estrus. The effects of the infusion on the reproductive tract were clinically evaluated (transrectal ultrasonography, vaginoscopy) before treatment, during treatment, and 19 days after treatment. Endometrial biopsies were taken before treatment, after the 3rd treatment, and 19 days after the last infusion. 

3. Results

Intrauterine infusion of a water-based enrofloxacin suspension was associated with a transient, but not statistically significant, inflammatory response. There was a significant transient increase in intra-uterine fluid and its echogenicity. Endometrial biopsy grade showed a significant increase (p< 0.05) following the 3-day course of infusion but returned to pretreatment level on the next cycle.

4. Discussion

These findings suggest that a water-based enrofloxacin suspension may be useful for treatment of bacterial endometritis sensitive to enrofloxacin, without the deleterious effects seen with administration of the commercial product.

Acknowledgments

Conflict of Interest

The compounded formulation used in this study was donated by Rood and Riddle Pharmacy. The compounded product was used because the FDA-approved product is not appropriate for intra-uterine use. The agent for the compounding pharmacy did not review this paper and was not part of the study

design or data collection or data analysis. Knowledge of the contents of the compounded formulation were made available to the primary investigators. Three authors (Schnobrich, Bradecamp, Barber) work for Rood and Riddle Equine Hospital, which is affiliated with the Rood and Riddle Veterinary Pharmacy. Dr. Lisa K. Pearson has no conflict of interest, Dr. Ahmed Tibary has no conflict of interest.

Footnote

^a Compounded solution contains Xanthan gum, Polysorbate 80, sterile water, and USP grade Enrofloxacin powder.