Effect of polyacrylamide hydrogel injection into reproductive tract of mares

Urogenital problems are common in older, multiparous broodmares. Vesicovaginal reflux (VVR) or “urine pooling” is a condition where urine refluxes from urethra and accumulates within cranial vagina. Currently, treatment for this condition involves medical management and surgery. Caudal relocation of transverse fold or extension of urethra are surgical procedures utilized to treat VVR. Currently, injectable therapies designed to bulk tissue surrounding transverse fold have not been utilized to treat VVR. Use of a polyacrylamide hydrogel to alter vestibulovaginal fold anatomy may be an adjunctive treatment option for VVR in mares. Polyacrylamide hydrogel is a nontoxic and nonimmunogenic biocompatible, nonabsorbable polymer gel that consists of 2.5% cross linked polyacrylamide and 97.5% sterile water.1  This compound has been utilized safely for soft tissue augmentation and urinary incontinence in women for several years. 2 Objective was to evaluate Synamid ® (Contura International A/S, Sydmarken 23, 2860 Soeborg, Denmark) injection safety into vestibulovaginal mucosa of normal mares. Ten mares (aged 7 - 15 years) were utilized. Prior to procedure, physical examinations and thorough reproductive evaluations were performed. Subjects were administered 3 ml of saline and 3 ml of Synamind ® in separate sites, randomly assigned to 1 cm to either right or left of midline (urethra) in transverse fold. Mares underwent daily physical examination, transrectal palpation and ultrasonography, vaginal speculum examination, and digital examination of vagina for first 7 days, then at days 15 and 30. Daily physical examinations revealed no systemic abnormalities in all mares treated. Hematoma formation at injection site occurred in 7/10 mares, which was observed starting at 24 hours postinjection. Hematomas persisted for an average of 3 days. No pain was elicited on palpation of vestibulovaginal fold in any mares. A palpable bulge was present on Synamid ® injection site for 30 days in 9/10 mares. In conclusion, no severe complications were observed with injection of Synamid ® into transverse fold in mares. There is a potential for this long lasting product utilization in “urine pooling” mares to augment vestibulovaginal anatomy and in mares with issues of vulvar incompetence. Further research is needed to determine this product’s efficacy in treating these conditions.

Keywords: Mare, urine pooling, polyacrylamide hydrogel

References

1. Broder K, Cohen S: An overview of permanent and semipermanent fillers. Plast Reconstr Surg 2006;118(3 Suppl):7S-14S.
2. Kasi AD, Pergialiotis V, Perrea DN, et al: Polyacrylamide hydrogel (Bulkamid® ) for stress urinary incontinence in women: a systematic review of the literature. Int Urogynecol J 2016;27:367-375.

This manuscript was originally published in the journal Clinical Theriogenology Vol 12(3) Sept 2020.  Clinical Theriogenology is the official journal of the Society for Theriogenology (SFT) and the American College of Theriogenologists (ACT).  This content has been reproduced on the IVIS website with the explicit permission of the SFT/ACT.