Examination of the mare's vagina
Keywords: vagina, equine, examination
Image size: 300 x 329 px (full size)
Congenital and acquired pathology of the vagina make it essential to perform routine pre-breeding per-vagina examinations, especially when natural breeding is used.
When artificial insemination is used, vaginal defects are usually discovered when a gloved hand is inserted into the vagina during insemination. In the case of Thoroughbreds, where natural breeding is the norm, failure to recognize structures such as persistent hymens and remnants of the mullerian system will result in breeding accidents. Such an accident (A in the amalgum image above) is shown below in image where a persistent hymen was not noted before natural breeding:
Image size: 500 x 593px
Although a speculum examination can be used to diagnose many vaginal defects, a gloved hand examination is frequently more rewarding, especially with cervical injuries. This is because one is often able to palpate injuries when they are not obvious during speculum examinations; especially during estrus when the cervix is flaccid.. For completeness, both examinations should probably be done.
More can be seen on exit than entry during a speculum examination. This is because structures such as a partially persistent hymen or a medial wall of the mullerian system are moved to the side by the speculum and bypassed during its passage inward. These structures reveal themselves as the speculum is withdrawn,
Image C shows a mass of large varicose veins in the cranial vagina of an aged mare.
Image size: 723 x 470px
This postmortem specimen shows how large these vessels can become; often causing hemorrhage that is visible at the vulvar lips. Hemorrhage often occurs during late gestation or during estrus under the effect of high serum estrogen concentrations. In such cases, owners must be assured that this is not a sign of impending abortion.
Image size: 1500 x 1122px
Image D shows an intact hymen, bulging through the vulvar lips in this mare in lateral recumbency. The mare was under general anesthesia when this image was taken. causing the hymen to twist on its dorso-ventral axis, with the medial wall of the mullerian system providing a central raphe to the structure.
Although persistent hymens are more common in heifers than maiden mares, persistent or partially persistent hymens are common enough to warrant routine vaginal, pre-breeding examinations. Occasionally a complete hymen can become so stretched (presumably due to changes in intra-abdominal pressure) that it may cover a fully inserted speculum or extend, sock-like, through the vulva lips.
