We finally know why dogs shiver when wet
If you’ve ever known a dog, you’ve probably had this experience: Sitting outside by the pool on a hot day, you throw your canine friend a stick. Fido fetches it, then comes to you, gives you smiling dogs and runs cold water on your dry clothes.
Scientists have finally found the reason dogs perform this operation. According to new research, the “wet dog shake” is a receptor defect in the mammalian skin called C-LTMR. And it causes all kinds of furry animals, from dogs to cats to mice, to move in a strange way when stimulated by drops of liquid on the back of the neck.
“It’s a complex behavior,” said Dawei Zhang, who wrote the research as a doctoral student at Harvard Medical School’s Howard Hughes Medical Institute. The study was published today (Nov. 7) in the journal Science. Across individuals and species, Zhang told Live Science, animals tend to vibrate at the same time and in the same alternating pattern — usually three vibrations at a time. one – and no one knows what receptors and nerves were responsible.
New genetic tools helped Zhang and colleagues find out, but identifying the cause of the movement took a little detective work. First, researchers made genetic changes in mice that could knock out the receptors in the skin that detect mechanical force, or receptors that detect temperature changes. They found that mice with no ability to sense a change in temperature still moved when drops of oil were sprayed on the back of their necks (the most reliable way to make a “wet dog” move). But mice without mechanoreceptor channels did not move.
So Zhang and his team focused on mechanoreceptors, tracking their activity in response to oil droplets. They narrowed their focus to three receptors, all of which respond to intense touch. Next, they used a technique called optogenetics to activate specific receptors in the skin with light. In this way, they could challenge individual nerve types without any liquid substance.
The results were clear: When the researchers stimulated a type of nerve called C-fiber low-threshold mechanoreceptors (C-LTMRs), the mice moved as if they had been given a sudden shower. In a double check, the researchers created mice without C-LTMR and found that they moved 58% less than normal mice when they were soaked in water.
C-LTMRs have always been a mystery, Zhang said. He said that they are suspected of making animals have strange feelings based on research done 80 years ago, but it is not clear how much influence the animals had. In humans, related mechanoreceptors called C-mechanoreceptors have been associated with pleasant, brushing sensations on the skin.
C-LTMRs contain signals from the follicles of the undercoat of fur animals, so the new study suggests they are specialized for detecting small, irritating objects such as parasites. crawling or water droplets, Zhang said: “In fact, it is a self-defense method to find. remove potentially harmful substances from their fur.”
Whether humans, with their hairless skin, have vestiges of this vibrational response is an open question. “I was giving the answer that people use a towel to dry,” Zhang said. But there is a common sensation of a slight vibration on the back of the neck in humans – it is not clear if that vibration is related to what a wet dog can feel before it vibrates.
“It’s hard to connect whether this is a product of a mouse mutation or a furry wet dog that moves,” Zhang said. “Maybe so, maybe not.”
Another unique secret: Why do dogs have to come to you to relieve themselves? It may be more difficult to solve that problem.
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