X-ray video reveals how dogs drink
Dogs don't have cheeks to trap liquid, so how do they manage to drink? Alfred Crompton and his team from Harvard University fed a dog some dark broth to observe the process, followed by X-ray video to reveal details of the tongue action.
A recent study showed that cats drink by drawing milk upwards as it clings to the tip of their tongue. Although dogs have a similarly-shaped mouth, it was suggested that unlike cats, they curl their tongues backwards and scoop up liquid.
Crompton's analysis proved that this isn't the case: cats and dogs use the same basic mechanism to lift liquid into their mouths. Although X-ray footage did show that a tiny depression forms on the back surface of a dog's tongue as it lifts up a column of milk, the scooped-up liquid simply spilled out of its mouth. So dogs are simply messier drinkers than cats.
Another difference is that dogs trap milk in tiny folds on the roof of their mouth between sips, allowing them to reach for more milk without losing the previous drops. But even so, it took this dog three laps to finish the contents of a bowl. Drinking just isn't as easy as it seems.
From New Scientist.