Rectal prolapse after trauma to the vagina during foaling

Keywords: foaling, trauma, rectum, prolapse, intussusception

A pony mare foaled approximately 48 hours before these photographs were taken. The foal (shown in the inset image) had hind-limb arthrogryposis and only lived for short time after birth.

Two hours after parturition, the mare's rectum prolapsed and was reinserted by an attending veterinarian. A circumferential retention suture was placed around the anus.  Shortly afterwards, the mare began to show signs of shock and severe pain. She was euthanized.

The top image shows how the end of the rectal intussusception has come to lie within the caudal part of the rectum. A finger has been inserted into the end of the intussusception. The anus is indicated by the yellow arrow. The vulva lips can be seen just below the tail of that arrow. U indicates the uterus. To assist one in understanding this image, a smaller color coded version has been created beneath it.

Image size: 1451 x 942px

Image size: 726 x 471px

In this color coded image, the section of rectum that contains the intussusception is colored red and the intussusception itself is colored blue. The wall of the unaffected rectum is colored yellow.

One presumes that the rectal intussusception was a sequel to a painful birth and straining, possibly because of trauma to the soft birth canal caused by the deformed fetus. However the uterus, cervix (green arrow) and vagina only showed the degree of contusion pictured below. Many would consider that to be consistent with normal foaling so the cause of straining remained uncertain.

Image size: 1468 x 1040px

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.

Image size: 990 x 747px

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:

Image size: 800 x 600px

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.

1232 x 919px

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.

Image size: 1200 x 1008px Copyright Dept. Theriogenology, ISU. Ames, Iowa.

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. 

Severe iatrogenic trauma during foaling.

Keywords: iatrogenic, foaling, trauma, equine

A nine year old Standardbred mare had an assisted foaling because of an apparent "hip lock". This was regarded by the author with circumspect because hip lock is rare in mares due to their large pelvic sizes compared to cattle*. It is perhaps more likely that the foal had unilateral or bilateral hock flexion i.e. "dog sitting" posture:

Image size: 805 x 492 px. Source unknown; contact lofstedt@upei.ca to verify copyright.

Either of these postural abnormalities may have been resolved partially or completely during traction. The nature of assistance was unclear but non-human mechanical forces may have been involved.

Image size: 1492 x 2088px

A live foal was extracted. However, the mare appeared to be partially paralyzed in her hind quarters and was unable to rise.  Her heart rate was elevated at 80 beats per minute and later rose to 130 beats per minute despite treatment with an NSAID and fluids.  The mares packed cell volume was 37% but may have remained high because of splenic contraction.  Hemorrhage from the vulva lips was obvious, soaking the adjacent pasture (see inset).  The owner elected to euthanize the mare.

The lower image shows some of the postmortem findings; extensive muscular and fibrous tissue necrosis within the vaginal wall. There was also subluxation of the mare's right sacroiliac joint. Severe coalescing vaginal and vulvar hematomas were also present.

Note: It is essential to determine the presentation, posture and position of a foal before traction is attempted. The foal should be repelled and posture should be corrected, preferably with copious lubrication. In most cases (unlike calves) the foal will be dead in prolonged cases of dystocia. It is difficult to repel a foal to correct malposture because epidural anesthesia is either unavailable or slow to take effect. In such cases, pulling out the mare's tongue will prevent closure of her epiglottis. Perhaps obviously, this will have no effect on myometrial contraction but will prevent the mare from straining voluntarily. This information is valuable to clients with pregnant mares because they will often provide assistance in foaling before the veterinarian arrives at the farm.

*The birth canal in a mature mare has a cross-sectional area of about 400 square cm; a cow about 280 square cm.