The old adage “you can lead a horse to water, but you can’t make it drink,” has real-world merit. And a horse that isn’t drinking is a symptom of illness, especially colic.

Dr. Jamie Kopper with a foal patient. (photo courtesy J. Kopper)

For three vets in the United States, the idea of trying to improve water intake in sick and hospitalized horses was the subject of a study they published last December (2020). Called The Effect of Water Flavor on Voluntary Water Intake in Hospitalized Horses, it was co-authored by Dr. Jamie Kopper, a faculty member (DVM) at Washington State University (WSU) at the time of the study and currently on faculty at Iowa State University, Tessa J. Van Diest, who just completed her first year of vet school, and Clark J. Kogan. spoke with Dr. Kopper about the study and the importance and challenges of getting a horse to drink the right amount of water, along with some tips for horse owners.

HC: What made you decide to study the effect of flavoured water?

Dr. Jamie Kopper: People commonly flavor water to try and get horses to drink more, but to our knowledge there were no studies evaluating if this actually works or not. I think that assuming “we don’t know if it helps, but it doesn’t hurt” is dangerous ‒ because in truth, if we don’t know that it helps, we also don’t know that it’s not hurting them. So we set out to try and determine if these practices improved water intake.

HC: How important is voluntary water intake (VWI) for a horse? How much should a healthy animal consume per day?

DJK: Voluntary water intake is really important for maintaining gastrointestinal health, kidney function and hydration. Increasing water intake can help prevent colic (prevent impactions, improve GI motility) so we were hoping to find an easy means to improve water intake. A normal 500 kg horse at ambient temperature (not sweating) and not exercising should drink about 10 liters of water per day.

HC: What other options are there for increasing VWI if a horse isn’t well?

DJK: Using salt (table salt, lite salt and/or KCl) can be a great way to improve water intake. Dr. Hal Schott at Michigan State University has conducted several studies looking at this in horses.

HC: What was the most interesting finding in your study?

DJK: The most interesting thing to me was that horses actively avoided peppermint-flavored water, even though we commonly associate horses with liking peppermint! This underscored to me the importance of always providing horses with a fresh/clean/normal bucket of water any time you are adding flavor to another bucket. The horses strongly preferred regular water to peppermint and apple-flavored electrolyte water.

HC: According to the study, the flavoured water had negligible effect?

Adding sweet feed to water increased water consumption in some horses by about 50 per cent ‒ it’s not a ton, but they did, in general, seem to prefer this taste over plain water. It was beyond the scope of this project, but this could potentially be a way to keep horses drinking if they change locations and the smell or flavor of the water is off-putting. I definitely wouldn’t recommend using peppermint flavoring or apple-flavored electrolytes to increase voluntary water intake based on this study ‒ horses in those groups hardly touched those flavors.

HC: Can you put the stats into layman’s terms: how much the horses preferred sweet feed vs peppermint vs apple electrolytes? And compared to plain water?

DJK: Basically, horses drank about 1.5 times more water when they were given sweet feed-flavored water and regular water compared to those given regular water alone. Horses that were given peppermint or apple-flavored electrolyte water actually drank their water almost exclusively from the regular water buckets. The most important take-home for me from this study was to always make sure you’re providing regular water even when trying to “flavor” it with something seemingly tasty.