Equine veterinary journal2026; doi: 10.1002/evj.70210

Novel technique for correcting urovagina via urethral transposition in the horse.

McCarthy, R
·
Kamm, JL
·
Pierce, M
·
Huber, M

Abstract: Vesicovaginal reflux is a common cause of infertility in mares. Surgical correction is commonly recommended and involves caudal relocation of the urethral orifice which forces the urine to be expelled caudally. There have been several previously described techniques. Complications associated with caudal urethral extension occur in 11-33.3% of cases. Objective: To identify a novel technique for performing caudal urethral translocation that effectively corrects vesicovaginal reflux with minimal associated complications. Methods: In vivo experiment and clinical case series. Methods: The experimental study involved one normal horse. The procedure was then applied in three multiparous mares with urovagina that had been unable to conceive. Mares were sedated for a standing procedure and had a caudal epidural performed. The novel urethral translocation technique utilizing a sliding H flap with the removal of mucosa caudal to the urethral sphincter was performed. In the same procedure, a caudal relocation of the transverse fold was also performed. Mares were closely monitored for at least 1 month post-operatively. Clinical mares were followed for at least 1 year. The referring veterinarian and clients provided follow-up information. Results: The urethral transposition had no major complications in the experimental mare. In the clinically affected mares, the urethra was moved caudally by a mean of 4.17 cm (range 3.5-5.5 cm). Post-operatively, all clinically affected mares had no urovagina detected grossly on initial examination. Two of the three mares became pregnant on the second attempt post-surgery. One mare had intrauterine fluid visualised on ultrasound which improved with treatment for endometritis including bladder catheterisation and was able to become pregnant. This mare was presumptively diagnosed with post-operative urovagina. All mares foaled successfully post-surgery. All clients were satisfied with the procedure and outcome. Conclusions: The main limitation of this study was the small sample size. Conclusions: This proposed novel technique provides an alternative method to treat urovagina. Further investigation to determine reproductive soundness post-operatively and to compare to previous methods is warranted.

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Publication Date: 2026-06-07 PubMed ID: 42252254DOI: 10.1002/evj.70210Google Scholar: Lookup

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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

This study introduces a new surgical method to correct urovagina in mares by repositioning the urethra, aiming to reduce complications and improve fertility.
The technique was tested successfully on healthy and affected horses, showing promising results in resolving urovagina and restoring pregnancies.

Background and Problem

Urovagina results from vesicovaginal reflux, where urine pools in the vagina, causing infertility in mares.
Traditional surgery involves moving the urethral opening caudally (toward the rear), to expel urine away from the vagina.
Existing techniques have a relatively high complication rate, occurring between 11–33.3% of cases.

Objective

To develop and evaluate a novel surgical technique for urethral transposition that corrects urovagina effectively while minimizing complications.

Methods

The study had two phases:
- An experimental phase with one normal horse to test the technique.
- A clinical phase applying the technique to three multiparous (had multiple births) mares diagnosed with urovagina and infertility.
Mares were sedated and given a caudal epidural for a standing surgery to reduce risks associated with general anesthesia.
The new surgical technique involved:
- A “sliding H flap” to relocate the urethra caudally.
- Removal of mucosa (lining) behind the urethral sphincter to aid in repositioning.
- Caudal relocation of the transverse vaginal fold during the same procedure.
Post-surgery, mares were closely monitored for at least one month, with clinical cases followed for a year for longer-term outcomes.
Follow-up data was collected from veterinarians and owners to assess recovery and reproductive success.

Results

In the experimental horse:
- Surgery had no major complications, indicating safety of the technique.
In clinical mares:
- The urethra was successfully moved caudally by an average of 4.17 cm (range: 3.5 to 5.5 cm).
- No gross signs of urovagina were found during the initial postoperative exams.
- Two of the three mares conceived on their second post-surgery breeding attempt.
- The third mare showed some intrauterine fluid linked to endometritis (uterine inflammation), treated successfully and also became pregnant eventually.
- All mares delivered foals successfully after surgery.
- All clients were satisfied with the surgical outcome and overall procedure.

Conclusions

This novel urethral transposition technique offers a viable alternative for treating urovagina in mares.
The procedure appeared effective and safe in a small sample, with encouraging fertility outcomes.
Limitations include small sample size, indicating the necessity for larger studies.
Further research is needed to:
- Confirm reproductive soundness over time.
- Compare this method’s efficacy and complications against existing surgical techniques.

Cite This Article

APA

McCarthy R, Kamm JL, Pierce M, Huber M. (2026). Novel technique for correcting urovagina via urethral transposition in the horse. Equine Vet J. https://doi.org/10.1002/evj.70210

Publication

Equine veterinary journal

ISSN: 2042-3306

NlmUniqueID: 0173320

Country: United States

Language: English

Researcher Affiliations

McCarthy, Robert

Carlson College of Veterinary Medicine at Oregon State University, Corvallis, Oregon, USA.

Kamm, J Lacy

Carlson College of Veterinary Medicine at Oregon State University, Corvallis, Oregon, USA.

Pierce, Meredith

Oregon Performance Equinetics, Bend, Oregon, USA.

Huber, Michael

Carlson College of Veterinary Medicine at Oregon State University, Corvallis, Oregon, USA.

Grant Funding

Carlson College of Veterinary Medicine, Oregon State University

References

This article includes 15 references

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