New study describes why dogs are sloppy drinkers in general. The research findings also help to explain why bigger dogs make more mess than smaller ones. This topic and more related ideas were discussed during the presentation “How dogs drink water,” held at the American Physical Society’s Division of Fluid Dynamics Meeting in San Francisco.
The research team has been studying pet drinking habits for quite a while now.
“Three years ago, we studied how cats drink,” Virginia Tech assistant professor Sunny Jung said in a press release. “I was curious about how dogs drink, because cats and dogs are everywhere.”
Unlike humans, both cats and dogs cannot suck in liquids, because their cheeks help the lifestyle of a four-legged predator. Dogs may be omnivores but their wolf ancestors predominantly prey on hoofed animals such as deer, moose, elk, and caribou.
The first research study found that cats drink by a two-part process: it’s an elegant plunge and pull –when a cat gently places their tongue on the water’s surface and then rapidly withdraws it.This creates a column of water underneath the cat’s retracting tongue. Check out this video, for example, showing how a cat drinks milk in slow-mo:
“When we started this project, we thought that dogs drink similarly to cats,” Jung said. “But it turns out that it’s different, because dogs smash their tongues on the water surface—they splash a lot – but a cat never does that.”
Jung and colleagues found that when dogs withdraw their tongue from water, there is a significant amount of acceleration that is roughly five times that of gravity. It creates the water columns, which feed up into their mouths.
To see this, Jung placed cameras under the surface of a water trough to map the total surface area of the dogs’ tongues that splashed down when they drink.
They found that larger and heavier dogs drink water with the larger wetted area of the tongue. This shows that a proportional relationship exists between the water contact area of the dog’s tongue and their body weight. The volume of water a dog’s tongue can move increases exponentially relative to the dog’s body size.
The dogs’ tongue tip also requires that the dog must open his mouth more to take in the liquid when full of water. This action also results to a lot of splish-splash.
Observe this in this slow motion video. Imagine if the drinking container were a regular doggie bowl, water would be splashing it all over the place.
The team could only go so to discover the physiology behind dogs drinking water. They had to have the capability to change the parameters to see how they affected their ability. But since they could not actually alter a dog in any way, they used models of the dog’s tongue and mouth.
“We needed to make some kind of physical system,” Jung explained.
Jung and his colleagues used glass tubes for the model. They used the material to replicate a dog’s tongue. This permitted them to imitate the acceleration and column formation during the exit process. And after that, they measured the volume of water withdrawn. It was found that the column of water pinches off and detaches from the bowl of water, mainly because of gravity.
Dogs close their mouths just before the water column collapses back into the bowl.
The researchers are now studying different animal physiologies as well such as the diving dynamics of plunging seabirds, the skittering motion of frogs, and what happens to leaves when they respond to high-speed raindrops.
These findings will lead to a better understanding of fundamental properties of fluid dynamics that can be applied to technological advancements in everything – from medical equipment to manufacturing machinery.
Image and article source: Discovery News