It has been said that a horse can eat snow in order to get enough water to survive. This is not true. any animal eating snow will become dehydrated. Think about it, it takes 10 pounds of snow to make about 1 gallon of water. It tales 2100 calories (1.5 pounds of fat) to heat one gallon of water 1 degree (standard at 8 degrees C. less efficient at lower temperatures). A horse will stop consuming snow as soon as there is a decrease in it's core temperature. Always make sure your horse has a good supply of unfrozen water. Pond heaters and heated water pails don't cast much to run. removing ice from their pails works too.