To understand this, you need to know about the structure of a dog’s mouth. Dogs like the cats fall into the group of vertebrates that have incomplete cheeks.
This is the reason they don’t have the ability to close their mouth in a way to exert suction power.
In other animals like horses or sheep, they have complete cheeks that help them to suck water upward.
So, dogs use a mechanism known as lapping to draw water into their mouths. In this mechanism, their tongue doesn’t reach the bottom of the liquid. It just penetrates the water surface.
So, we can’t call it licking. Because in licking the tongue has to reach the bottom of the water vessel.
Dog water drinking mechanism- Step-by-Step.
As I’m not a scientific person, I don’t have the access to high tech tools to show the mechanism of dog drinking water. However, I found some remarkable research that studies on this subject matter practically.
Here is the process breakdown. Check out the video, and you will know for sure.
1. Align the mouth to the water level.
Due to the nature of the lapping, dogs must sit and bend down towards the water surface. At the point of drinking water, their mouth remains just a few inches away from the water surface.
This is the position where a dog is completely ready to gallop and quench their thirst.
2. The tongue is extended with backward curl.
After getting into the right position, it’s time for the tongue to come out. And the important thing to note is the shape of the tongue as it leaves the mouth.
It doesn’t come out straight onto the water surface.
First, dogs extend their tongue and then curls it up backward. This curled shape is known as a ladle.
3. Penetrates the water column.
It’s time to put the tongue into the water surface. At this point, the tongue of a dog makes an impact with the water. The splashing effect that you resonate with dogs starts here.
Note that, the tongue penetrates the water surface and goes a little below. It doesn’t just rest on the top of the surface. This is important because with more contact with the tongue, the amount of water to be lapped also increases.
4. Use upward force to build momentum.
Now is the time to pull the tongue back into the mouth. Dog’s use more force when they are pulling their tongue from the water surface. The acceleration remains between 1-2 g, and the speed accelerates at 0.7-1.8 m/s.
This forceful pull creates a water column beneath the tongue and gets pulled up against the force of gravity.
The back part of a dog’s tongue helps in bringing the water to his mouth. Most of the water from the front side of his tongue falls off.
5. Moves the tongue in and closes the mouth.
The only thing now left to do is take the tongue inside and close the mouth. Just before the dog bites or closes his mouth, the water column pulled up gets into the mouth.
So, the timing of the bite is crucial here. Little late and the water column will drop below.
How is it different from cats?
The process of a cat drinking water is a little different from a dog.
Dogs splash water as they drink it. But with cats, you will never see splashing. That’s the reason cats are known as neat drinkers.
Here are the differences:
A cat’s tongue doesn’t penetrate the water surface.
It uses only the backward curl of the tip of the tongue to pull the water in.
Cats extend and pull the tongue rapidly.
At the point of pulling the tongue in, deceleration happens and remains between 1-2 g. Almost half that of the dog. This slow pulling back is what keeps them away from splashing.
Here’s a video from BBC Earth Unplugged demonstrating the differences: