Rectal Tears in the Horse
Dr. Melissa Mazan
A rectal tear is a tear through one or more of the layers of the rectal wall. These tears can be superficial, deeper and through the inner layer, or penetrate through all layers of tissue. Blood on the veterinarian's sleeve immediately after rectal examination
Rectal tears may occur as a result of a breeding accident, or due to other trauma, but the most common cause of a rectal tear is the rectal exam. The internal examination or rectal exam, is an essential tool for diagnosis of diseases within the abdominal cavity and for breeding management. The rectal examination is used as a part of the physical examination in colic, to determine if there is a displacement, twist, or distension of the intestines, to try to determine what portion of the intestines are involved. In this regard, the rectal exam is important for determining the need for surgery. It is also used to determine if there are masses (such as an abscess or tumours) in the abdominal cavity and to determine whether a mare is ready to breed, whether a mare is pregnant, and, at later stages of the pregnancy, whether the fetus is alive.
Rectal tears occur just as commonly to inexperienced practitioners as to experienced practitioners. The severity and seriousness of a rectal tear will depend on the depth and length of the tear. A simple abrasion – a tear that only extends to the first layer of tissue – may even go unnoticed. A deep tear, or one that goes through all layers of tissue, can be life-threatening. Tears that occur closer to the abdominal cavity are also more dangerous.
Predisposing factors concerning the horse include obesity, excessive movement of the horse during rectal exam, and dehydration (the latter two are common with a colicky horse). Rectal tears may be more common in certain breeds, such as Arabians, but this is not clearly proven.
Young, nervous horses and aged horses seem to be more prone to rectal tears, as do stallions and geldings due to their smaller pelvic canal.
What to Watch For
Signs of abdominal discomfort after a rectal examination
Your horse may roll, paw, repeatedly go up and down, or look at his sides
Signs of shock after a rectal examination: Your horse may be shaky, sweat and have a very high heart rate
Blood at the anus or on the hind legs or tail within 12 hours after rectal examination
As soon as your veterinarian suspects that there is a rectal tear, he or she will inform you of the accident, and then will take emergency steps to deal with the problem. Remember, rectal tears are a recognized complication of any rectal exam, and cannot always be avoided.
Your veterinarian will usually choose to sedate the horse heavily before proceeding further, then perform a bare-handed rectal exam in order to determine exactly where the tear is and how deep it is.
If the tear is superficial, then it can often be managed quite easily. Your veterinarian will often choose to place your horse on broad-spectrum antibiotics, and will usually give mineral oil using a nasogastric tube in order to soften the feces. Your horse may do better with low fiber feeds for several days to a week. This type of tear usually heals without any major complications.
Tears that extend through all but the last layer of the tissue of the rectum can be life-threatening. If the abdominal cavity becomes contaminated the horse has a very poor prognosis.
In the case of a deep tear, the horse should receive emergency treatment at the farm. This will include broad spectrum antibiotics, a tetanus booster, and in some cases an epidural to numb the area and prevent the horse from straining. The horse should be transported as quickly as possible to a referral institution for surgical repair.
Repair of a rectal tear must be done in two stages; consequently it is both time-consuming and expensive. The first surgery is a colostomy, in which an alternative area for defecation is created in the horse's flank. This allows the tear to heal on its own. The second surgery reconnects the colostomy to the rectum.
Even with appropriate emergency treatment, a horse with a deep rectal tear has a guarded prognosis.
If your horse has sustained a minor, superficial tear, then there is a little in the way of home care that must be done. It is important to follow your veterinarian's directions for giving antibiotics and keeping the manure soft. You should watch carefully for any signs of hard manure, difficulty or straining with defecation, or signs of colic.
When your horse is sent home after the first surgery, he will need food that helps to maintain soft, moist feces. This may include green grass, lots of fresh water, and very well-soaked hay.
Although the majority of rectal tears probably cannot be prevented, there are a few things that you can do. Make sure that your horse is very well-restrained and possibly sedated for any rectal exam.
The extent of your precautions very much depend on the particular horse. An experienced broodmare is at very low risk and is unlikely to need any sedation, but a young stallion is at high risk for a rectal tear, and probably needs not only sedation but also active restraint such as a twitch.