There’s A Scientific Reason Behind Why Wet Dogs Shake
If you’re a dog owner, you’ve most likely experienced your canine companion coming up to you and shaking cold water off its fur after running through the sprinklers on a summer day or after receiving a bath.
A team of scientists has finally uncovered why dogs do this curious behavior when they’re wet. According to new research, a receptor in mammal skin called C-LTMR is responsible for the shake.
It causes furry animals like dogs, cats, bears, and mice to perform a unique and consistent shake when they get wet or need to remove irritants from their skin. The shaking effectively flings water from their coats into the air around them.
Previous research has shown that animals across individuals and species tend to shake at the same frequency, with usually three back-and-forth shakes at a time. Yet, scientists were in the dark as to why. Until now, the neural mechanism behind the shaking has not been studied.
To learn more about the behavior, the research team conducted experiments where they tested several types of stimuli on wet mice. In the new study, they created genetic mutations in mice that would remove the ability of skin receptors to detect mechanical forces or temperature change.
Then, they applied oils, water, and puffs of air to the backs and necks of the mice to see how they would respond. They found that the mice without the ability to detect temperature change still shook when oil droplets were sprinkled on the backs of their necks.
However, mice without mechanoreceptor channels did not shake. So, the team focused on mechanoreceptors and measured the responses of the mice by stimulating them with oil.
They were able to narrow down the culprit to three receptors, which all react to very light touch. They also used a technique known as optogenetics to activate certain skin receptors with light, triggering individual nerve types without any liquid stimulus.
One receptor called C-fiber low-threshold mechanoreceptors (C-LMTRs) led to consistent shaking in mice when they were stimulated. Removing C-LMTRs in mice caused them to shake 58 percent less than normal mice when drizzled with water.
C-LMTRs have long been suspected of creating ticklish sensations in animals, according to research conducted about 80 years ago. But it was unclear how animals experienced the stimulus.
In humans, similar mechanoreceptors called C-mechanoreceptors have been linked to pleasurable, brushing touches on the skin. The new study suggests that C-LMTRs are meant for detecting tiny, annoying stimuli like water droplets or parasites.
“Essentially, it’s a defensive system to get rid of potentially harmful stimuli that’s on their fur,” said Dawei Zhang, a co-author of the study and a doctoral student at the Howard Hughes Medical Institute of Harvard Medical School.
“It’s difficult to correlate whether this is an evolutionary product of the rodent or furry animal ‘wet dog’ shake. Maybe it is, maybe it’s not.”
The study was published in the journal Science.
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