Vestibulo-vaginal hypoplasia in a mare.

The research focuses on an unusual case of vestibulo-vaginal hypoplasia, or the abnormal development of the vaginal and vestibular areas, in a mare. This rare condition was observed during a routine breeding soundness examination of an 18-year-old Welsh cross thoroughbred pony mare.

Description of the Case

• The mare had previously not been bred, and the owner was well-acquainted with her health history.
• A routine breeding soundness examination revealed the presence of hymenal remnants. These remnants were manually broken down, leading to the release of a small volume of fluids that had built up in the area.
• Upon further examination, it was found that there was a significant constriction in the mare’s vagina widely believed to be due to vestibulo-vaginal hypoplasia.
• The narrowed passage could not be enlarged even with gentle manipulation. An endoscopic investigation found normal vestibule and rear vagina, but a uniform constriction extending from the urethral orifice for about 8 cm.

Additional Medical Findings

• In addition to the stricture, ultrasound examination was conducted to provide a clearer view of the reproductive system.
• The uterus and uterine horns were found to be of normal sizes, with the body of the uterus being 20 cm in length.
• The ovaries were also found to be normal in size though the left ovary contained a 5.5 cm diameter follicle, and the right ovary had small follicles.
• With the exception of the vaginal area, all other parts of the mare’s reproductive system were considered normal.

Implications and Conclusion

• Given the length of the stricture, it was not feasible to conduct surgical intervention.
• Due to the high risk of dystocia (difficult or abnormal labor), the mare in question was not bred.
• Indeed, this case provides insights into an unusual occurrence of vaginal strictures due to what is believed to be congenital vestibulo-vaginal hypoplasia, previously unreported in mares.