After a wet romp, many hairy mammals—especially dogs—instinctively shake off the water clinging to their fur. It’s not just about drying off. This shake helps to “remove excess water from fur and also potentially eliminate irritants, tangles, and parasites,” according to a recent study conducted by researchers from the Howard Hughes Medical Institute at Harvard Medical School. In their work, published November 7 in Science, the researchers discovered that this behavior is driven by particular mechanoreceptors in the skin that respond to touch.
Read also: Woman Returns $500 Cash She Found in Costco Parking Lot – Internet Has Mixed Reactions
The team found that a specific group of receptors, known as “C-fibre low-threshold mechanoreceptors (C-LTMRs),” activate this shake reflex. These receptors, which “wrap around hair follicles,” detect slight touches and play a key role in triggering the shake, which can be an “effective way to remove water from fur” and clear hard-to-reach areas. The researchers noted, “hairy mammals have over 12 types of sensory neurons and each have their own function to find and interpret various feelings and trigger responses like shaking,” yet the mechanisms behind the wet-shake behavior have largely been “unexplored.”
Mechanism Behind the Shake
The study involved exposing lab mice to different stimuli, including “oil and water,” applied to their “backs and necks,” to observe the reactions of various mechanosensory neurons. By genetically modifying some of the mice, the researchers removed “most of their C-LTMRs.” Without these receptors, the mice stopped shaking, which suggested these receptors were “essential to controlling the sensation that is essential for triggering the wet dog shake.”
The team’s research went further, mapping the sensory pathway from the C-LTMRs through the nervous system. They found that the signals triggered by C-LTMRs reach the “parabrachial nucleus—an area in the brain that helps process pain, touch, and temperature.” Using advanced techniques to control neurons with light, the team was able to “switch on and off” the spinal neurons involved, tracking how the signals travel. In comparison to control mice, those that were genetically altered showed “a 58 percent reduction in shakes.” Blocking this neural pathway reduced the shaking behavior, suggesting the brain’s parabrachial nucleus “is the neural circuit specific to wet dog shakes.”
Future Directions and Potential Applications
The researchers highlight that “future research into this common behavior could investigate if overactive C-LTMRs add to conditions like twitch-skin syndrome in cats.” This syndrome involves cats experiencing sudden skin twitches and ripping sensations, potentially due to “overactive C-LTMRs,” which may also contribute to skin hypersensitivity in humans.
By examining this neural mechanism, the researchers are taking steps towards understanding “one of nature’s simplest yet most effective behaviors in mammals,” paving the way for further insights into how these sensory receptors operate across different species.