Prepubic Tendon Rupture in Horses: High-Risk Late Pregnancy Complication

Prepubic tendon rupture is a serious late-gestation injury in which the tendon and nearby abdominal support tissues at the front of the pelvis partially or completely tear. This structure helps hold up the heavy pregnant uterus and abdominal contents. When it fails, the mare can become suddenly painful and unstable, and the abdomen may appear to drop lower than normal.

This condition is most often recognized in the last weeks of pregnancy. In some mares, the change is dramatic and rapid. In others, especially with partial tears, the signs can build over days. Because abdominal wall tears, hernias, hydrops, and other reproductive emergencies can look similar, your vet usually evaluates these problems together as high-risk late-pregnancy body wall defects.

Prepubic tendon rupture is dangerous for both mare and foal. The mare may have severe pain, trouble moving, and difficulty pushing during labor. The foal may face risks related to prematurity, fetal stress, difficult delivery, poor oxygenation, and trouble nursing after birth if the udder is badly swollen.

The exact cause is not always clear. Most cases happen late in pregnancy, when the uterus and foal place maximum strain on the mare's abdominal support structures. In many mares, the problem may involve both the prepubic tendon and nearby abdominal wall tissues rather than a clean, isolated tendon tear.

Reported risk factors include older age, multiple previous pregnancies, draft breeding, twin pregnancy, and hydropic conditions such as hydroallantois or hydroamnion. Trauma may also contribute in some cases. A very heavy uterus, excess fetal membrane fluid, or abnormal body wall stress can all increase the chance of tissue failure.

Because several different late-pregnancy disorders can produce abdominal enlargement and edema, your vet may not be able to name the exact tissue that failed on the first exam. What matters most early on is recognizing that the mare is high risk and needs prompt stabilization, pain control, and close monitoring.

Diagnosis is usually based on history and physical exam findings rather than one perfect test. Your vet will look for the classic pattern: a heavily pregnant mare with ventral edema, pain, reluctance to move, altered abdominal shape, mammary gland displacement, and sometimes bloody secretions from the teats. A complete rupture is often easier to recognize than a partial tear.

Ultrasound is commonly used to assess fetal heart rate, fetal activity, placental health, and the amount of abdominal or uterine fluid. It can also help your vet look for related problems such as hydrops or placental disease. Even so, imaging may not clearly distinguish a prepubic tendon rupture from an abdominal wall tear because the late-term uterus and foal limit visibility.

Your vet may also monitor mammary secretions, gestational age, pain level, heart rate, respiratory rate, and the mare's ability to stand and walk. These details help guide the next decision: continued supportive care, attended natural foaling, induction when the foal appears mature enough, referral for surgery, or humane euthanasia if suffering cannot be controlled.

There is no guaranteed way to prevent prepubic tendon rupture. Because the exact cause is not always known, prevention focuses on identifying high-risk pregnancies early and reducing avoidable strain on the mare. Older broodmares, draft mares, mares with twins, and mares with hydropic pregnancies deserve especially close late-gestation monitoring.

Good reproductive management matters. Early twin detection and reduction when appropriate, prompt workup of abnormal abdominal enlargement, and regular late-pregnancy exams for mares with a history of complications can help your vet catch problems before they become catastrophic. If a mare develops unusual ventral edema, udder changes, or discomfort, do not assume it is normal late pregnancy.

Your vet may also recommend practical steps such as limiting strenuous activity, maintaining appropriate body condition, and monitoring mammary development and fetal well-being in high-risk mares. Prevention is really about vigilance: fast recognition, early veterinary involvement, and a clear foaling plan for mares whose pregnancies are not following a normal course.