Concerns that hospitalized horses that did not consume enough water and could develop colic led to testing different water flavors often used in veterinary settings. The winner of the taste test was sweet-feed flavored water, which the test group horses significantly preferred over plain water.
If you’re going to try flavoring a horse’s water to try to get them to drink more, it’s always important to give them a bucket of normal water as well, said James Kopper, DVM. Sometimes the flavor we think they might like, they don’t and they drink less.
Source: Paulick Report, April 27, 2021. Link. Kopper suggested that horse owners set up their own taste test at home in advance to determine which flavor a horse prefers. Then they can carry that flavoring with them when they are away from home and add it to the water if the horse shuns the unfamiliar taste.