April 24, 2018
Colic In Pregnant Mares by Frederick Harper, Ph.D., Animal Science - Beef, Sheep, Horse, UT Ag. Ext. Service Colic and founder are as dreaded by horse owners as a diagnosis of cancer is for us. Colic is especially bad for a pregnant mare. Even if she lives, she may not have a foal. In the pregnant mare, colic is the condition that most requires veterinary attention. But fortunately, most colic cases in pregnant mares require minimum treatment and pose little danger to the mare or fetus. About 82 percent of mares medically treated for colic survived in one study, but only 44 percent of the mares survived colic surgery. The survival rate was 59 percent for mares in the second trimester of pregnancy, 50 percent for mares in the third trimester and 30 percent for mares near foaling. Loss of a fetus is a major concern when pregnant broodmares colic. The loss rate in mares after they had coliced is 16-18 percent, which is slightly higher than in pregnant mares that don't colic. Loss tends to occur up to 60 days after colic surgery. When mares were only treated medically for colic, the loss rate was 12 percent, but was nearly 20 percent if mares had colic surgery. Another study reported that losses were four times more likely for pregnant mares treated for colic. Losses after colic are often due to endotoxemia, which usually occurs when the large colon is twisted, an inflammation develops in the intestine or an incarceration of the small intestine occurs. Clinical signs of endotoxemia, such as depression, anorexia, rapid heart rate and dehydration, occur in a high percentage of mares that abort. Endotoxins from bacteria in the intestinal tract aren't normally absorbed into the circulatory system. If endotoxins are absorbed into the blood stream, the color of the mucus membranes are altered, capillary-refill time prolonged and heart and respiratory rates increased. Experimental endotoxemia results in embryonic loss in pregnant mares. In pregnant mares, colic is a disorder of the digestive or reproductive tracts. The most common digestive-tract problems in pregnant mares are large-colon impaction, displacement and twisting. In the reproductive tract, colic is caused by uterine twisting, contractions associated with expulsion of fetal membranes, prolapse, tears and arterial hemorrhage. Signs of mild to moderate colic pain in pregnant mares includes yawning, pawing, dullness, lying down and occasional rolling. To prevent colic in pregnant mares, inspect them daily, immediately get veterinary assistance at the first signs of colic. Most colic in pregnant mares occurs within two weeks of changes in feeding or exercise programs. Don't make rapid changes in the feeding program of pregnant mares; make sure they get plenty of exercise and have clean, fresh water at all times.
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