Colic can strike at any time and has many known and not so well understood factors. During fall and winter, the risk is particularly high. Fortunately, there are several things you can do to decrease your horse's colic jeopardy.
Most people know they should transition slowly when adding or changing grains and other concentrates. However, it is important to realize that a change in forage, including hay types, should also be made gradually. This is because the protein, sugar and starch components of hay are digested in the small intestine, and while digestive enzymes there can adjust to changes, it takes time.
Undigested fractions then spill over into the large intestine, where the resident microorganisms must deal with them. Hays also contain a variety of fiber types and complex plant carbohydrate compounds that can only be fermented in the large intestine. The bacteria, protozoa and, to a lesser extent, yeasts in the large intestine work together to efficiently ferment. For example, some species will ferment starch, sugars and fructans into lactate while others will use that lactate as their fuel, preventing acidosis that could harm the fiber fermenting organisms. The population of organisms in the large intestine will mirror the food that is presented to them but efficient adaptation takes time. Allow at least 5 to 7 days to make a complete change.
If that sounds complex, it is. The moral of the story is to avoid rapid changes in diet, including substituting hay for grass and changing hays. Disruptions in organisms that occur with rapid changes can cause gas and possible displacement of the colon, diarrhea from incomplete fermentation, even changes in how well the intestine contracts and moves food along.
Inadequate water consumption is the leading cause of impaction. An average size horse needs to consume at least 4 to 5 gallons of water per day even in very cold weather because for much of their journey through the bowel, intestinal contents have a high moisture level, much like soup. In addition to what the horse drinks, fluids are actively secreted along the intestinal tract, then reabsorbed in the terminal portions of the colon. The fluid keeps things moving freely and allows for good mixing, which assists in absorption and fermentation.
But how to get them to drink? The horse is most likely to drink while, or shortly after, eating hay, so hay and water should be placed close together. Warm water is consumed more readily. At the very least, water should never be allowed to freeze over. To encourage drinking, add at least one ounce of salt to the feed daily, or dissolve and spray on the hay for picky horses.
Intake can be increased by adding warm water to pellets, hay cubes, even sweet feeds. Adding some wheat bran improves appeal. Beet pulp is ideal because it can hold four times its weight in water.
The final colic risk factor, especially in winter, is inactivity. Do not reduce turnout and stall the horse unless weather is really severe. When conditions are so bad the horse is barely moving, ensuring adequate water intake goes a long way toward preventing impaction colic.
Eleanor Kellon, VMD, currently serves as the Staff Veterinary Specialist for Uckele Health & Nutrition. An established authority in the field of equine nutrition for over 30 years, Dr. Kellon is a valuable resource in the field of applications and nutraceuticals in horses. She formerly served as Veterinary Editor for 'Horse Journal' and John Lyons 'Perfect Horse' and is owner of Equine Nutritional Solutions, a thriving private practice. A prolific writer, Dr. Kellon is the author of many best-selling books on a variety of medical and nutritional topics and has contributed to both lay and professional publications.