Suck It Up
Posted by Julie Andrewski on January 5, 2006
Q: Why do dogs and cats lap water with their tongues rather than suck it down like humans, cows, horses, etc. It seems such an inefficient means.
A: Good question and one I didn't have an immediate answer for. I've given your question some extra thought and done a bit of research and have an explanation that "works" for me - not sure it's entirely correct but I'll share.
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To make drinking possible in humans, cows, and horses, it is essential that a seal be made with the lips at the water's surface. With a seal in place, any negative pressure within the oral cavity makes it possible for the water to be pushed into the mouth. It sounds strange, but the water is pushed into our mouth, not sucked in. I think making a lip seal is the crucial element in this behavior. Dogs and cats have a kind of cleft lip that probably makes it difficult, if not impossible, for them to make a seal. Lapping may not be as efficient, but it does get the job done. Thanks for your thought-provoking question.
John Wiessinger ( January 6, 2006)