Any type of colic can happen at any time of year, but when the weather turns cold the incidence of painful gastrointestinal impactions typically rises sharply. Most winter impaction colic is related to hydration---or, more accurately, mild dehydration. Horses tend to drink less when the weather is cooler, causing ingesta0 to become drier and more likely to become impacted. Combine that with increased consumption of hay, which is more likely to cause blockages than fresh pasture grass, and the stage is set for colic.
To protect your horse from impaction colic this winter, ensure that he always has access to fresh water. Multiple studies have attempted to identify an “ideal” temperature for water in the winter months, but there are so many variables---such as ambient temperatures---that the results are difficult to apply universally. Nonetheless, it’s a pretty good bet that ice will dissuade a horse from drinking, so do your best to keep his water from freezing---not only in a solid sheet of ice on top of the trough or bucket but also as free-floating chunks of ice.
A wide range of devices, from insulated buckets to heated automatic waterers, are available today to keep water from freezing. Make sure whatever method you choose can be safely powered by your barn’s electrical system.
Another way to prevent impaction colic during the cold months is to keep your horse moving. Movement---even just walking around a pasture---encourages gut motility. Keep your turnout schedule as consistent as you can all season. Even on cold, snowy days, turn your horse out if he has shelter and the footing is safe. If conditions make his usual turnout unsafe, look for alternatives, such as hand-walking in the indoor arena or even up and down the aisle for a half-hour at a time.
This article first appeared in EQUUS issue #460, January 2016.