Prepubic Tendon Rupture in Horses

Prepubic tendon (PPT) rupture is a rare but serious and painful condition that affects mares in the late stages of pregnancy. It is life threatening to both the mare and the fetus and requires emergency veterinary attention.

The prepubic tendon is a strong band of tissue that runs from the pubic bone to the abdominal wall of the horse. It provides the tension necessary to keep the lower half of the body in the proper position, and supports the heavy abdominal organs, including the uterus.

When the prepubic tendon tears, the horse no longer has the support it needs to hold its posture in the appropriate position, or to support its organs.

Older mares, especially those who have been pregnant more than once, are especially at risk. Mares with poor body condition also have a higher incidence of rupture.

Risk factors for PPT rupture include:

• Traumatic injuries earlier in the pregnancy
• Twin pregnancy
• Hydrops (swelling of the fetus)
• Draft horses or Standardbreds

The severity of prepubic tendon rupture depends on several factors including:

• Whether the tendon is ruptured partially or completely
• Whether other structures in the area are also torn
• How far along the pregnancy is
• Whether the mare’s pain is controllable or not
• Whether other complications occur

In cases where the tendon is only partially torn, supportive care may be sufficient to allow the fetus to mature enough to survive. Cases where the tendon is completely torn are more severe.

In cases where other structures in the body such as the abdominal musculature and the rectus abdominis muscle are also ruptured, the severity and complexity of the problem are slightly greater. Horses may show more severe symptoms.

Fetuses require a minimum of 330 days of gestation before birth to be able to survive. The later the rupture occurs in the pregnancy, the higher the chances of the fetus surviving after birth.

In rare cases, the PPT rupture leads to significant disorganization of the internal organs of the horse. It is possible for the bowels to become trapped amongst other structures, lose blood supply, and for the tissues to start to die.

The cause of these tears is not completely understood at this time. The weight of the abdominal organs, including the fetus, presses down on the tendon, and in some cases, the tendon cannot take the weight and it tears.

The main symptoms of prepubic tendon rupture include:

• Painful abdomen (colic)
• Sudden change in the shape of the abdomen, including progressive swelling, and poorly defined flanks
• Dropped pelvis with tipping of the pelvis towards the head of the horse
• Swollen udder
• Changes to the position of the udder where the teats point forwards rather than downwards
• Blood leaking from the teats

Diagnosis of prepubic tendon rupture is based on physical examination and ultrasound.

Deciding how to proceed with a PPT rupture is challenging as there are many variables that must be taken into account, and it is often not possible to save both the fetus and the mare. The variables include:

• The gestational age of the fetus (greater than 330 days is necessary for survival)
• The health and pain of the mare
• The relative value of both mare and fetus
• The nature of the rupture itself

Supportive treatment for partial prepubic tendon rupture is sometimes sufficient to allow the fetus to grow to term. Supportive care in these cases includes:

• Bandaging the abdomen
• Stall rest
• Pain relief
• Preventing infections with antimicrobials
• Progestin therapy to speed up the fetus’ maturation
• Dietary management to reduce the bulk of feces

Other options that must be considered in prepubic tendon rupture include:

• Medically induced abortion of the fetus
• Pain control and intensive management for the mare until the foal can be delivered
• Euthanasia

In cases where the birth of the foal is possible, the mare does not have sufficient muscle strength to deliver by herself due to the rupture. Birthing assistance is required.

Foals that are born after PPT rupture require ongoing care after the birth. Due to difficulties nursing, or in the case of mare euthanasia, the foal typically requires colostrum supplementation to ensure good health.

In cases of partial prepubic tendon rupture where the mare’s pain is controllable and the fetus is close to full term, the prognosis for both mare and fetus are fair.

In cases where the gestational age of the fetus is less than 320 days when the rupture occurs, the prognosis for the fetus is grave.

In cases where the rupture is complete, especially when other structures in the abdomen rupture, or when the bowel becomes trapped, the prognosis for the mare and foal is poor to grave.

In some cases, mares that have survived the birth of a foal after a PPT rupture need to be euthanized due to uncontrollable pain.

Mares that survive a PPT rupture long term should not be bred again as the condition is very likely to recur.

There are no proven preventative measures to avoid prepubic tendon rupture. Strategies to minimize the risk include:

• Keeping the horse fit and active prior to breeding
• Breeding less often with more time between pregnancies
• Avoiding breeding older mares

Prepubic tendon rupture is rare in horses.

• Supportive care
• Abortion
• Euthanasia