Prepubic tendon rupture can be a sequel of hydroallantois, hydroamnios and twinning.
Abdominal wall infection.
May occur spontaneously, without any predisposing factors.
Rupture of prepubic tendon and/or abdominal muscles can occur together or separately in late-pregnant mares.
Heavy pregnant uterus → increased weight on ventral abdomen → separation of ventral abdominal musculature from its attachment to the pelvis via the prepubic tendon or internally → sudden appearance of ventral displacement of caudal abdomen → accompanying edema.
Mare becomes progessively more uncomfortable and unable to move.
Rupture of the uterine vessels can occur.
Obviously abnormal and enlarged (ventral) abdominal silhouette.
Mare unwilling to move/uncomfortable.
Cranial displacement of udder is pathognomic for rupture of the prepubic tendon rupture, and helps to distinguish prepubic tendon rupture from other causes of enlarged (ventral) abdomen/abnormal abdominal silhouette in mid-late pregnant mares.
Pregnant mare in late gestation; often older and unfit.
Sudden appearance of ventral displacement of caudal abdomen and cranial displacement of udder.
Prolonged excessive ventral edema that is painful.
Difficulty in moving and reluctance to lie down.
Ventral ruptures and rupture of the pre-pubic tendon often present in similar ways and can occur together but they should be differentiated if at all possible.
Abdominal wall ruptures
Large swelling at flank or caudal ventral abdomen. Palpation per rectum may reveal a rent in the body wall.
Abdominal pain, usually mild to moderate but increasing if structures pass into the rupture.
Progressive thick plaque of painful ventral wall edema - more obvious than the mild ventral edema commonly seen in mares close to term, which is not usually painful.
The mare may lie down or stand unusually in order to relieve pain.
Mares can still walk and pelvic/mammary gland orientation are normal.
Prepubic tendon rupture
Severe ventral abdominal swelling .
Cranial positioning of mammary gland.
Progressive generalized ventral wall edema.
Reluctance to walk and lie down.
May assume 'saw-horse' stance-cranial pelvis tilted ventrally (tailhead and tuber ischii elevated) from abdominal viscera weight and inability of lumbar muscles to maintain normal orientation of back/pelvis.
Distinguish ventral abdominal wall rupture from pre-pubic tendon rupture.
Identify site, size and type of ventral abdominal wall rupture.
Identify possible contents of rupture (i.e. structures which have herniated through the ruptured abdominal wall).
Occasionally abdominal defect can be palpated in cases of ventral abdominal wall rupture (but not with simple cases of prepubic tendon rupture).
In cases of both ventral abdominal wall rupture and prepubic tendon rupture extensive severe edema makes accurate palpation difficult.
May help differentiate different causes of abnormal abdominal silhouette.
May be possible to palpate rent in body wall in cases of rupture of the ventral abomdinal musculature.
May be possible to palpate entrapped viscera in cases of rupture of the ventral abdominal musculature.
Confirmation of diagnosis
Discriminatory Diagnostic features
Cranial displacement of the udder in cases of prepubic tendon rupture.
Definitive diagnostic features
Gross autopsy findings
Rupture of prepubic tendon or abdominal musculature.
Other causes of ventral edema.
Initial symptomatic treatment
To save the mare, treatment of choice for pregnant mare with prepubic tendon or ventral wall rupture is parturition. In mares close to term this can be natural, or if earlier in gestation this may be induced Reproduction: parturition - induction. Note high risk to mare and foal.
In cases not close to term, owners may wish to try and enable the pregnancy to continue in order to facilitate the birth of a viable foal nearer to full term. This is a high risk strategy for the survival of both the mare and the foal.
Where attempts are being made to support the pregnancy until parturition:
An abdominal support or bandage can be used to help maintan support to the abdominal muscles/prepubic tendion (and use may be continued post-foaling).
Ventral ruptures can be surgically repaired if limited in size and edema has subsided.
Repair of prepubic tendon ruptures are not possible.
Maintain the mare until a live foal can be delivered.
Euthanasia Euthanasia is common (any may be necessary on welfare grounds) in mares with prepubic tendon rupture or large abdominal wall ruptures.
Feed appropriately for condition and growth of fetus.
Regular exercise is important to keep mares fit.
Early detection and resolution of twin pregnancies.
Prepubic tendon rupture: poor to grave.
Large abdominal wall rupture: poor to grave.
Small abdominal wall rupture: fair to good for mare:
Some repair spontaneoulsy following foaling.
Can be repaired surgically.
Prognosis for return to breeding remains poor as structures are likely to fail again during subsequent pregnancies - use embryo transfer.
Where previous rupture of the ventral abdominal wall/prepubic tendon rupture makes it impossible for a mare to carry a foal to term herself, future reproductive capacity might be salvaged by using embryo transfer Embryo transfer, ie recovering an embryo form the mare at day 7-8 of pregnancy, and transferring it to a healthy recipient mare.
Expected response to treatment
Attempt to salvage mare.
Attempt to salvage foal.
May be necessary to make a choice between salvaging the mare and foal e.g. attempting to increase the foal’s chances of survival by supporting the pregnancy until closer to the full term date of gestation will reduce the mare’s chances of survival by increasing the chances of the rupture progressing.