LORI.equine

Per rectal evisceration after foaling

Keywords: trauma, equine, mare, foaling, rectum

The first image shows a six year old mare presented shortly after her first foaling.  Despite video surveillance, foaling was rapid and consequently, unattended. The birth of a live foal was followed immediately by evisceration from the anus. As shown in inset A, a temporary purse string suture had been placed around the anus by the rDVM.

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When the purse string was released, intestines burst out of the anus as shown in inset B. The placenta remained hanging from the vulva lips. The intestines had passed out of the peritoneal cavity through a tear in the rectum. Blood on the operator's glove after detection of the rectal tear:

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The injury to the rectum was not caused by the foal because neither the uterus nor the vagina were damaged. This defies a simple explanation. It is possible that the rectum may have ruptured due to high abdominal pressure during foaling but the author is not aware of previous reports of such an accident. The mare was euthanized

More commonly evisceration occurs through vaginal tears.  The image below show how viscera can escape through the vagina. Note that the cervix and even the cranial vagina lie well within the peritoneal cavity, cranial to the reflection of the peritoneum in the recto-genital pouch. This anatomy makes it possible to perform ovariectomy via colpotomy in both mares and cows. However it becomes a potential liability in mares during foaling. This is because foaling is far  rapid than calving and a foal's forelimbs are more likely to traumatize the cranial vagina than is the case for calves. This is especially so if the foal is in foot-nape posture during second stage. If the foal’s hooves penetrate the vagina where it lies within the peritoneal cavity, intestines can enter the vagina through the site of penetration.

The image below clarifies this. LUH and RUH are the left and right uterine horns. PR is the peritoneal refection, edged by a red line, in the recto-genital pouch. The green lines show the cranial and caudal extents of the cervix. The red arrow points to a common site of vaginal penetration, the roof of the cranial vagina. The curved yellow arrow shows how intestines can move into the vagina. The rectum can be seen as a shaded body above the genital tract.

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In the image below, a foal's legs penetrated the cranial vagina, entering the recto-genital fossa. This allowed the intestines (yellow arrow) including the large colon, to escape from the peritoneal cavity. Such cases are invariably fatal.

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It is important to note that evisceration may occur some time after the birth of the foal, when the mare lies down and pressure is exerted on the abdomen. Evisceration through tears in the uterus is also possible, through the open cervix. Both vaginal and uterine tears can be present in mares that appear to be totally normal.  Although some owners object to potential interference with dam-offspring bonding immediately after foaling, the author always requests permission to examine the cranial vagina and uterus (as far cranial as possible) at that time.

The reader should be aware that it is far more common for a foal's hooves to tear through the caudal part of the vagina than the cranial part of the vagina. Tears often occur through the dorsal wall of the vestibule and there may even be total ablation of the perineal body. In those cases there is no danger of evisceration.

Note: Foaling accidents appear to be more common in maiden mares than pluriparous mares. This may be because the tract is smaller and less distensible in younger, than older animals. Also, maiden mares may panic and strain excessively during this novel experience.