Pathology of lethal peripartum broad ligament haematoma in 31 Thoroughbred mares.

This research explores the origin and progress of broad ligament haematoma, a life-threatening condition, in postpartum mares. The study shows that the disease, which leads to massive internal bleeding, is predominantly likely to develop in mature, multiple-birth mares and primarily originates from injuries to the proximal uterine artery.

Study Methodology

• Researchers conducted a pathological analysis of 31 mares that had died due to peripartum broad ligament haematoma to identify the bleeding sites.
• For comparison, the arterial distribution of 5 younger mares with several parities was studied, which served as negative controls.

Research Findings

• It was evident that age and multiparity were the primary risk factors for developing broad ligament haematoma.
• The majority of arterial injuries occurred in the uterine artery (24 out of 31 mares), with the proximal uterine artery being the most common site for rupture.
• The injuries frequently occurred at bifurcations, the lateral part of curvatures, and sudden bends in the artery.
• Three types of injuries were identified: ruptures with and without longitudinal fissures, and transections.
• Examination of the arterial wall revealed atrophy of smooth muscle cells, fibrosis of the tunica media, and the disruption or calcification of the inner elastic lamina.

Conclusions

• Arterial injuries, mainly occurring in the proximal uterine artery, were primarily responsible for broad ligament haematoma in postpartum mares.
• Atrophy of smooth muscle cells combined with fibrosis of the arterial wall was among the prime predisposing factors in older, multiparous mares.
• Transrectal echography, by monitoring small aneurysms, mural tearing, and medial fibrosis at the proximal uterine artery, could provide crucial information for the early diagnosis and possible prevention of broad ligament haematoma in peripartum mares.