Horses seem to colic when the weather changes. Veterinarians and horse owners have believed for decades that a weather change increases the chance of colic and I have certainly had this experience in my practice. No one really knows the exact cause of this increasing number of colic cases, but in the spring and fall as the weather quickly changes, the number of colic cases increase. I think one possibility is that horses seem to drink less water with the weather change and a drying of the ingesta can lead to an impaction. A student at the University of Pennsylvania did a thesis paper on the relationship between barometric pressure changes and the incidence of colic. The study concluded that the best predictors of colic are age, the horse’s geographical latitude, the incidence of previous colic events, and barometric pressure drop within 12 hours of the event.
For each additional year of age, the odds of colic increase slightly every year. However, for every barometric pressure decrease in inches of mercury of atmospheric pressure, the odds of colic increase 2 ½ times. In the northern hemisphere, the study also found that the farther north a horse lives, the more variable the climate and the more stress the animal experiences adapting to the environment, with the chance of a colic increasing by two for every degree of latitude moving north. With the bad weather, managerial changes occur that may alter feeding schedules, turnout and exercise, and other types of changes in routine that cause stress. So, when a low-pressure frontal system passes through your area, monitor for colic very closely over the following 12 hours.