Uterine rupture in the mare.

The research article discusses a case study of a mare (female horse) that was subjected to fatal uterine rupture during mating with a stallion. The study inspects potential causes of the rupture and concludes that mares should undergo thorough medical examination before mating, particularly if recently after parturition (giving birth).

Clinical History

• The primary focus of the study is a 14-year-old Welsh Mountain Pony mare which was put to mate with a younger stallion, 9 days after giving birth.
• The failure of mating during the first two hours and leaving them together overnight resulted in the mare’s death.
• The next morning, it was discovered that a portion of the mare’s small intestine was externally protruding, with more of it further away on the ground.
• A manual vaginal examination unveiled a tearing along the mare’s dorsal cervix and uterus.
• The stallion remained healthy following the incident, continuing to mate with other mares later on.

Post-mortem Examination

• The autopsy determined that there had been a significant haemorrhage (bleeding) in the mare’s abdominal cavity.
• There was an 11-inch tear running up both the cervix and uterus, despite the walls of the vagina remaining intact. The wound was still fresh with no peritoneal adhesions suggesting it happened at parturition.
• The uterus was weak and contained some pus, indicating possible infection. The left uterus horn was much larger than the right one, suggesting incomplete uterus involution (return to a non-pregnant state).
• A small soft follicle on the left ovary was also observed.

Discussion

• Such injuries are rare and are often caused by a large size discrepancy between the genitalia of stallion and mare, or forced mating.
• In this case, neither factor seemed likely as the stallion had successfully mated with mares of similar size previously and the mating was unrestrained.
• The study theorizes that during mating, the mare’s over-dilated cervix allowed the penis to forcefully penetrate through the cervical canal to the uterus, causing the fatal rupture.
• The accident underpins the potential risks of mares mating shortly after parturition when the uterus is still enlarged and awaits returning to its original non-pregnant state which makes it prone to injury.
• The study proposes thorough medical check-ups for mares, ensuring adequate involution before allowing them to mate after parturition.