Water Temperature and Horse Drinking Behavior

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Why might our horses drink from an ice cold creek or tank rather than from the heated water buckets? Equine behaviorist Dr. Sue McDonnell explains.

Posted by Sue McDonnell, PhD, Certified AAB | Nov 18, 2019

Q: A few years ago I read an article describing research done at New Bolton Center on drinking behavior. It said that the research showed that in winter, horses prefer to drink warm water rather than ice cold water, and as a result veterinarians recommend giving horses warm water during the winter to be sure that they drink enough.
So, that winter we hung buckets of water along the fence every morning and evening at feeding time. It seemed our horses drank very little warm water from the buckets. Instead, they kept going to the stream even when it was partially frozen over. On days that the stream was completely frozen, they would drink from the buckets. We thought they might not like something about the hanging buckets, which were quite a distance from their hay racks.

So, the next year we put a heated plastic stock tank in the pasture near the hay racks. We put in a large heating element so the water stayed warm to the touch. Again, once we started heating the water in the tank, our horses seemed to drink mostly from the stream, as if they really preferred the ice cold stream water to the warmed water in the tank.

This year, the day before Thanksgiving, we had a sudden cold snap. I filled up the stock tank, but forgot to plug in the heating element. In the morning, there was a thin layer of ice on the tank. We were surprised to see that the horses had been drinking from the cold tank, breaking through the icy crust. Anyway, I turned the heater on so it wouldn’t freeze. After two weeks of paying close attention, I’m pretty sure they don’t seem to drink much at all from the tank when the heater is on. They are going back to the icy stream.

My veterinarian and I were talking about this, and she thought you might have been involved with drinking behavior research cited in the magazine article, or that she might have heard you talk about it somewhere. Was that you, or do you know about it? Do you have an explanation why in these circumstances our horses drink the ice cold water from the creek or tank rather than the warm water in the buckets or the water that is warmed in the tank? It would seem they actually prefer cold water over warm water.

—Robert, New York

A: Thank you so much for bringing up this question...

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