How Dogs and Cats Overcame Their Drinking Problem

by Malcolm Riordan, DVM

In having to drink from a standing position with their head down, our best friends had to have a method to overcome gravity — how to lift water when they drink. This drinking problem was overcome by necessity long ago — yet our understanding of their method of drinking was not accurate until 2010/2011.

While we humans drink sitting or standing up, and are able, with our developed cheek/lip muscles, to seal our lips and to suction up our daily hydrations, dogs and cats have neither our positional advantage nor the ability to use suction.

Of course they manage. A cat lapping up water is quite subtle and appears dainty — especially as compared with dogs who create a water park at their bowl with their noisy splashy version of the lapping technique to quench their thirst.  And here it is not that, compared to cats, dogs are crashing oafs. It's that dogs have more water and more pendulous lip to manage.

In the last few years there have been significant and interesting changes to how we believe our pets drink water. Most people still consider that our dogs and cats are ladling up their water using the reverse ladling shape of their tongue tip. Ladle-swallow, ladle-swallow. This has been held by assumption to 'obviously' be the technique we witness at the water bowl.

The recent discoveries show that both dogs and cats use the same method to drink water – but this method is not 'ladling' or scooping as it would appear and has been assumed.

Put simply, the method is that the quick dart of their tongue (with its curled tip to increase size) into and then out of the fluid's surface pulls up a column of water up into their mouth. Just as this column of liquid has risen to its full height and is momentarily suspended, they close their mouth down/'bite' on it. The column of water becomes trapped in their mouth, over the tongue and can now be swallowed. This is not the same as mechanical ladling, rather it is plunk-bite-swallow, plunk-bite-swallow.

Researchers observed that the water which is (inadvertently, not purposely) ladled is lost in splashing and falling back out as it does not get into a position over the tongue to be available for swallowing – the ladled water ends up beneath the dogs' tongue and largely just splashes or falls out owing to gravity. And without thick muscular cheeks and lips, there is no ability to get the ladled portion of the water over the tongue. Thus it is only the induced column of water that is in position and available to be swallowed. Plunk–bite-swallow is the name of the game. The ineffective ladling is just a sideshow.

Cats induce a column of water too, but with a slighter back-curling of the tongue as it is plunked into the water – much less ladling loss under the tongue there, and their lips/cheek muscles – though they only are covering the closed mouth passively, they are much less so pendulous and floppy than for their larger, messier, and noisier canine brethren.

The research group determined that cats repeat the drinking motion sequence (plunk-bite-swallow) 4x a second.

It is funny here that in order to fully establish this recent discovery, it took both collusion and disagreement between researchers from MIT and Harvard! This matter will be explained in the video listed below by none less than a Harvard professor.

If you like, you could go forth and roust your friends and family – and win some bets with this: Cats and dogs do not drink by 'ladling' with their tongue!! 

To see for yourself - a video being worth ten thousand words - watch this two minute Reuters News report video clip: Dr. A. W. Crompton, a Harvard biology professor explains and two high speed videos (300 to 600 frames/second) are shown in slow motion to expose this method our best friends use to drink.  

All images are owner-submitted photos to the HSUS Spay Day 2012 Pet Photo Contest. Come out to Woods Humane Society or click on the logo and take a look through some of the 100+  adoptable dogs and cats waiting for you to 'graduate' them into a new life.

Woods Rafter Cat Image on Banner by Malcolm Riordan.