Pneumovagina in Horses: Windsucking Mare, Conformation, and Fertility

Pneumovagina is the abnormal entry of air into a mare's vagina. Many horse people call this a "windsucking mare". It usually happens when the vulva does not close tightly enough to keep outside air, dust, manure, and bacteria out of the reproductive tract.

In a healthy mare, the vulva, vestibulovaginal fold, and cervix act as protective barriers. When the outer seal is poor, air can be aspirated into the vagina during movement. Over time, that repeated contamination can irritate tissues and raise the risk of vaginitis, uterine inflammation, and reduced fertility.

Pneumovagina is often linked to body shape and tissue tone rather than a contagious disease. Older mares, thin mares, and mares that have had multiple foals are more likely to develop it because the perineal tissues may become more relaxed or sunken. Some mares also have a naturally sloped or poorly positioned vulva that makes the problem more likely.

This condition is not always an emergency, but it matters most in breeding mares. If your mare has trouble settling, has repeated uterine infections, or makes a noticeable sucking sound from the vulva when walking or exercising, your vet should evaluate her reproductive conformation.

The usual cause is poor perineal conformation. In practical terms, that means the anus may be sunken, the vulva may tilt forward, or too much of the vulva may sit above the pelvic brim. When that happens, the vulvar lips do not stay tightly apposed, so air can enter more easily.

Body condition also matters. Thin mares often have less fat and soft tissue support around the perineum, which can make the problem more obvious. Age and repeated foaling can stretch or weaken the tissues that normally help seal the reproductive tract. Trauma from foaling or breeding can also damage the vestibulovaginal fold, another important barrier against contamination.

Pneumovagina may occur by itself or alongside related problems such as urine pooling, vaginitis, or chronic endometritis. In breeding mares, these linked issues are often what bring the mare to your vet in the first place. A mare may not seem painful, but fertility can still be affected.

Because conformation plays such a large role, this is not something a pet parent causes through routine care. It is usually a structural issue that becomes more noticeable with age, weight loss, athletic condition, or reproductive history.

Your vet diagnoses pneumovagina by combining history with a careful reproductive exam. They will look at the mare's body condition, the angle and position of the vulva, whether the anus is sunken, and how well the vulvar lips meet. Parting the vulvar lips helps assess whether air is readily aspirated and whether the vestibulovaginal fold is still functioning as a barrier.

A vaginal speculum exam is often used to look for irritation, discharge, urine contamination, or signs of chronic inflammation. In broodmares, your vet may also perform rectal palpation and ultrasound to check the uterus and ovaries, especially if there is a history of infertility, fluid in the uterus, or pregnancy loss.

If infection is suspected, your vet may recommend uterine culture, cytology, or biopsy as part of a breeding soundness workup. Those tests do not diagnose pneumovagina by themselves. Instead, they help show whether the poor seal has already contributed to endometritis or other fertility-limiting problems.

Diagnosis is usually straightforward, but deciding what to do next depends on the mare's goals. A lightly affected riding mare may only need monitoring, while a broodmare with repeated contamination or infertility may benefit from surgical correction.

Not every case can be prevented, because conformation is a major factor. Still, there are practical steps that can lower risk or reduce complications. Keeping broodmares in appropriate body condition can help support the perineal tissues, especially in older or thin mares that are more likely to develop a poor vulvar seal.

Routine reproductive exams matter for mares with a history of infertility, discharge, urine staining, or repeated uterine infections. Early identification of poor perineal conformation gives your vet a chance to discuss management before contamination becomes a bigger fertility problem.

For mares already known to have pneumovagina, prevention focuses on limiting repeat contamination. That may include breeding-season monitoring, timely correction with a Caslick when appropriate, and prompt evaluation of any discharge or failure to conceive. If your mare has had a Caslick and becomes pregnant, make sure the closure is opened before foaling as directed by your vet.

The goal is not to chase one perfect plan. It is to match the mare's anatomy, breeding goals, and risk level with the right level of care. Your vet can help you decide whether monitoring, surgical correction, or referral is the best fit.