Looking at the Fur: Why Do Dogs Shake Themselves?
The Rhythm of Shaking
Whether it's a mouse, a dog, or a lion, when they get wet, mammals shake themselves to rid themselves of the water. Depending on their size, they swing their bodies back and forth at different speeds. An American researcher has now developed a formula that can be used to calculate the respective frequency.
Shake instead of rub.
Just like humans, mammals try to stay as dry as possible in wet weather to protect themselves from hypothermia. However, since fur-wearing animals don't have a towel to rub themselves dry with, they have to get the water droplets out of their fur in other ways.
This is easily observed in dogs: They shake their bodies so thoroughly that drops fly. They remove approximately 70 percent of the water in the process. This technique is common across mammals—from mice to lions. The only difference is the rhythm, or frequency, of the shaking.
Optimal Shaking Frequency:
Andrew Dickerson of the Georgia Institute of Technology in Atlanta, USA, filmed 16 different mammal species and five dog breeds shaking themselves dry using special high-speed cameras. The result: Large mammals, such as bears and large dogs, shake themselves about four times per second. A small mouse, on the other hand, needs about 30 shakes per second to dry off.
Dickerson discovered that the shaking frequency of animals is related to their mass and even found a formula for it. According to this formula, the shaking frequency corresponds roughly to the animal's mass to the minus 0.22 power.
The connection is logical: a certain centrifugal force is required to cause the water droplets to fly off. Small animals with a small body radius are at a disadvantage. They compensate for this with a higher shaking frequency. If a mouse were to shake itself as slowly as a dog, it would still be just as wet as before.
Why dogs shake
Wet dog, shake. Everyone has probably seen a wet dog shaking itself. However, this behavior can also occur in other contexts. "Dogs shake themselves Рexcept when they are wet or have rolled around Рas a displacement activity or after a stressful situation to release tension," explains Christiane Wergowski, veterinarian and founding member of the Professional Association of Dog Trainers and Behavior Consultants (BHV) . But it can also be to remove irritating elements from their skin or fur, according to Dr. Barbara Sch̦ning, a veterinarian specializing in behavioral science and animal welfare.
"Shaking can therefore also be a symptom of, for example, an ear infection," says Schöning. And sometimes our four-legged friends simply shake themselves after we've petted them, in order to "tidy up" their fur.