The Wet Dog Shake

Does it ever seem like your dog takes pleasure in saturating you after having just gone in the water? Are you one of the many dog owners who knows your dog will, like clockwork, shake the water from his or her coat all over you on purpose (well it seems like it’s on purpose)? If so, you’ll be happy to hear about a new discovery.

Scientists at the Georgia Institute of Technology, have recently learned how fast a drenched pup must “shimmy” to dry themselves off. Whereas most people would run for shelter just before their soaked pups prepared to unload, these scientists repeatedly entered the splash zone to gather the information they sought.

By using a slow-motion video camera, the scientists analyzed the shaking. What they found was smaller dogs tended to dry themselves off faster by shaking more immediately and with greater ferocity. David Hu, assistant professor at the Institute noted that it all related to the dogs necessity to sustain its body heat. Drying wet fur via a shake is a mechanism of thermal insulation.

Hu noted that simply evaporating water would be very costly to a dog. If a 60-pound dog sat around waiting for the process of evaporation to complete itself, they would have to spend a quarter of their daily calories to dry off, and for a smaller dog, it would take even more of their daily energy.

Hu stated, “Physiologist call this the wet-dog shake. That’s why this thing evolved, and it’s basically a slight variation of shivering.” The study encompassed 16 different species of animals and for dogs, in particular, breeds such as the Chihuahua, Labrador, Poodle and Husky.

Though the researchers did get wet, it was a small price to pay for the mathematical relationship they developed that included the radius of the animal and the frequency with which it had to shake off to become dry again.

The formula in a nutshell, goes something like this: the smaller the animal the more rotations needed. A mouse with a radius of smaller than an inch (2cm) would need to shake with a frequency of 27 shakes per second. A dog with a radius of 20 cm would need to shake with a frequency of just under 5 shakes per second to get approximately as dry as the mouse.

Leave a Reply

Your email address will not be published. Required fields are marked *