The average size horse drinks 10 to 12 gallons of water per day. Draft horses may drink up to 15 to 20 gallons of water a day. A lactating mare or a horse that has sweated a lot will drink more. Cold weather increases feed or energy intake so the horse can tolerate the weather. Many horses consume more hay. Water has a role in moving digesta through the intestine. Lack of fresh, unfrozen water is the number one cause of colic during the winter due to intestinal impaction. One of the worst disasters is if the horse does not have access to water. If a horse cannot drink or the water is frozen, the horse becomes dehydrated. Twenty-four hours of water deprivation can cause a horse to lose 4% of its body weight. Forty-eight hours of water deprivation can cause a horse to lose 6.8% of its body weight and after 72 hours, body weight loss has increased to 9%. Dehydration symptoms may include dry mucous membranes, sunken eyes, slow capillary refill, tucked up appearance and loss of elasticity in skin. The horse will also start reducing feed intake and may ultimately refuse to eat.
A heated water bucket, heater in water troughs, and a heated automatic watered are options to provide unfrozen water. Without heaters, make sure the ice is broken on the horse’s water supply. You could encourage the horse to drink by providing lukewarm water or water between 40 oF and 75 oF. If you are using a submergible electric water heater in a water trough, check to see if it is giving off stray voltage and shocking the horses when trying to drink. Personally, I have had problems with horses stopping drinking even with electric water heaters in troughs. I would place my hand in the water trough and they felt fine but the horses were not drinking. I then took water buckets out to the horses and they drank freely. Most likely, the water heater released a small current that the horses felt but I did not with my hand. I replaced the heater and the horses started drinking again. Automatic waterers are more difficult to assess. Make sure the heating element is on and there is no stray voltage. Try to observe the horses drinking to get a true assessment if they are using an automatic waterer.