By Heather Smith Thomas
One of the techniques used by veterinarians for colic diagnosis is palpation per rectum: reaching into the rectum with a well-lubricated plastic glove/sleeve, to try to feel adjacent portions of the digestive tract and other organs—to determine what’s going in inside the animal.
Cid Hayden, DVM (Salmon, Idaho) says this procedure is not without risk. If the horse is moving around or straining against the intruding arm, delicate rectal tissues could be injured. Rectal tears may require emergency abdominal surgery to correct.
“In an animal with colic, the risks are greater. The horse already has abdominal pain, and there may be a lot of pressure from a distended bowel. An impaction or sore spot might cause the horse to react,” he says.
“When trying to check internal areas of the abdomen, no one has an arm long enough to feel the entire abdomen of a horse. We are usually palpating the rear one-third at best, and can’t feel everything we need to check. We’re trying to feel for an abnormality or for a normal organ that’s not where it’s supposed to be,” says Hayden.
“In those situations it’s not so much that you can feel what’s wrong, but the normal anatomy is not where it is supposed to be—and if it’s missing, where did it go?” The veterinarian may be able to interpret certain displacements, and is often trying to decide if surgery (or a more lengthy and involved diagnostic procedure) is needed.
In a hospital setting, colic diagnosis may include ultrasound, or a laproscopic examination or flank surgery, or major abdominal surgery. In the field, or at a small clinic, tools and techniques are often limited to trans-rectal palpation, listening to gut sounds with a stethoscope, and doing a belly tap. The basic exam will include checking heart rate, respiration rate, capillary refill time and checking the gums, for shock.
“Color of the gums and other color changes can be clues regarding whether the horse is becoming toxic from endotoxin release or other problems,” says Hayden.
Listening to the abdomen with a stethoscope can reveal whether or not there are any gut sounds, their frequency, and the type of sounds. “A horse with no gut sounds means things are shut down,” he says.
A belly tap (sticking a sterile needle through the belly wall to obtain fluid) enables the veterinarian to check for white blood cells and inflammatory cells, fibrin, etc. “We can do other tests on that fluid, to get an idea about how serious the horse’s condition might be,” he explains. A thorough examination consists of many pieces of information, to envision the larger picture.
Is the horse passing manure? He may pass a little at first and then cease—if there is something farther up the tract causing blockage or shutdown. Examination of manure may give clues. “If it’s very dry, this can indicate problems. Sometimes it might have sand in it,” he says.
“In a colic situation, the owner should check vital signs. Have a stethoscope and know how to use it. Know what your horse’s normal heart and respiration rate is, and listen to bowel sounds. Even though you may not be able to differentiate between various types of breathing, pulses and gut sounds, you can count bowel contractions and gurgles—how many per minute. If you write down (for each horse) the normal heart rate, respiration rate and gut sound rates this gives something to compare to in an emergency. Check those 3 things and after you walk the horse around check again. If these aren’t going back toward normal after an hour, call your veterinarian.”
“Check capillary refill. Lift the lip, find a pink spot on the gum and press it for a few seconds with your thumb. Take your thumb away and see how quickly it turns pink again. It should turn pink in 2 seconds or less. If it takes 3 seconds this indicates a little shock, 4 to 5 is mild shock, and 7 seconds or longer indicates severe shock.”