Researchers found that dogs' "sloppy" way of drinking are actually precisely timed high-speed movements designed to maximize their ability to raise fluids into their mouths.
With the aid of laboratory simulations and photography, the Virginia Tech College of Engineering researchers analyzed the precise movements that take place whenever a dog drinks. The study involved 19 dogs of various breeds and sizes. Thirteen dogs were filmed at the owners' residences while six were filmed at the Virginia Tech campus.
"Dog drinking is more acceleration driven using unsteady inertia to draw water upward in a column, where cats employ steady inertia," said Biomedical Engineering and Mechanics Associate Professor Sunghwan "Sunny" Jung.
The canine findings were compared to feline's way of drinking. Researchers found that despite the similarities in mouth structure, dogs and cats have different drinking techniques.
Without full cheeks, dogs and cats can't create suction to drink, unlike horses, elephants and humans. Using inertia, dogs and cats use their tongues to quickly raise the water upwards.
To the naked eye, both precisely timed movements happen so quickly. Researchers found that dogs are able to use their tongues faster compared to cats. Dogs rapidly plunge their tongues into the water and retract it immediately to create a water column that rises to their mouths.
Dogs also curl their tongues downward to raise a small ladle of water. To capture the water, dogs bite down immediately. They open their mouths again and repeat the process numerous times.
As the dogs' tongues are accelerated upwards, the water column also rises. The water that remains in the tongue's curled tip also gets thrown to both sides of the mouth, making the technique sloppier to the naked eye.
In comparison, cats' tongues touch the surface of the water lightly, based on previous research. Normally, cats do not fully immerse or plunge their tongues into the water. A neat water column forms when the water sticks to their tongue's upper side.
"This was a basic science study to answer a question very little was known about—what are the fundamental mechanics of how dogs drink?" added Biomedical Engineer Sean Gart who was involved in the study.
The findings were published in the Proceedings of the National Academy of Sciences journal on Dec. 14.