Intestinal impaction is a common ailment in horses. When the pipes are backed up, most horses exhibit some signs of colic. Most if not all horses will experience some form of mild impaction colic in their life. Some horses will become severely ill and require surgical correction. Fortunately, with proper treatment, more than 95 percent of horses that colic recover with no lasting problems.
From an engineering standpoint, the design of a horse' digestive tract is a disaster. At several points it narrows and makes a sharp turn. It' a wonder horses don't get indigestion with every meal!
"Feed is the most frequent culprit causing an impaction. One type of food is no worse than another. Hay, grain, and grass can all plug up the intestines," says Dr. Aimie Doyle, a veterinarian who completed an equine residency at the University of Illinois Veterinary Teaching Hospital. "Sand and gravel, when eaten, can also block the gastrointestinal tract. Rarely horses will eat the oddball foreign body. Horses are a bit smarter than dogs and don't try to eat everything in sight."
Water normally prevents horses from impacting each time they eat. Feed that is drier than normal, because the horse drinks less, can lead to an impaction. When less water is taken in with feed, the drier material in the intestines has an increased tendency to get stuck.
"Horses stop drinking for a number of reasons. Weather changes can upset some horses and cause them to change their water intake. Travel or other stress can cause a horse to not drink as much as normal. A sick horse should always be examined by a veterinarian for underlying disease," says Dr. Doyle.
An anecdotal theory is that horses fed on grass do not impact as much as those not on pastures. It is thought the water content in the grass facilitates smooth sailing down the intestines.
Unless your horse is Mr. Ed, it won't be able to tell you it is feeling under the weather. With a mild impaction horses appear generally uncomfortable and just not themselves. They may stop eating, act distressed, or circle in their stalls. Many horse owners are, unhappily, familiar with common signs of colic. If the impaction does not resolve, the horse becomes more painful and will start rolling.
"Rectal palpation and clinical signs are used together to diagnose an impacted horse. The pelvic flexure, the most common site of impaction, can be felt rectally. Palpation can also give us some idea of the degree of impaction but should only be performed by a veterinarian," says Dr. Doyle.
Medical treatment in the field consists of giving the horse mineral oil, and fluids, through a naso-gastric tube. Banamine, a non-steroidal anti-inflammatory drug frequently used in equine medicine, is an effective pain reliever at appropriate doses. Contact your veterinarian before administering any medications! The idea is to soften the feed ball and move it through the system. The majority of horses respond well to treatment and will not require further treatment.
It is important to stop feeding your impacted horse. Once a horse is impacted, more feed makes the impaction worse. Let the horse have all the water it can drink but no feed, no matter how much it whines. After the impaction resolves feed can be re-introduced over several days.
"If a horse is not responding to treatment at the farm, then it is important to get it to a referral clinic. The horse can be given IV fluids and monitored more closely. A horse that continues to be non-responsive could end up in surgery. The good news is that horses do very well after this surgery," says Dr. Doyle.
Call your local veterinarian if your horse is showing signs of colic. For more information on surgical treatment of colic or impaction, contact the University of Illinois Large Animal Clinic.
By Ann Marie Falk, Information Specialist
University of Illinois - College of Veterinary Medicine