Rupture of the prepubic tendon in a congenitally lordotic mare.

Abnormal conditions associated with parturition do not directly prevent delivery but may indirectly cause concern and become evident prior to labour (3, 8). The prepubic tendon is the tendon sheet attached to the abdominal muscles that supports the entire abdominal contents, including the uterus (10). Rupture of the prepubic tendon mostly occurs with a higher incidence in older drafttype (5, 7, 8, 14) (average age 11 years) and idle (14) mares that sustain trauma and/or carry more weight in the abdomen (5–8, 11, 14), i. e. hydrallantois, foetal giant or twins. Due to the many structures that insert on the prepubic tendon, all support of the ventral and lateral abdominal wall (5) and ventral support for the abdominal organs (7) are lost when it ruptures. Some mares develop obvious lordosis (11) wherein the pelvis is tipped cranially (4) to stabilize the pelvis and spinal muscles, which is normally achieved by the abdominal muscles (6). Almost all mares present with marked ventral oedema that is more pronounced than the oedema normally observed in mares close to term (5, 13, 14). The oedema is thought to be caused by compression of the epigastric and caudal superficial epigastric veins, which drain the ventral abdomen. However, it may also be due to the muscle damage in the area surrounding a rupture (8), as the prepubic tendon rupture may easily lead to rupture and haemorrhage of the adjacent musculature (11). Support for the udder is also lost, and it becomes swollen and congested (4). All reported cases involve pregnant mares (5, 7, 9) close to foaling (8). Since the abdominal musculature and contractions will not be competent to aid in foetal expulsion and dystocia is likely to occur (8, 13, 14), parturition should be induced and assisted (4, 8, 9, 13). The prognosis for survival of either foetus or dam is poor and death is the normal outcome (1, 6, 7, 13). The present case report appears to be the first case, which describes rupture of the prepubic tendon in a congenitally lordotic pregnant mare and its diagnosis using vaginal palpation.