A mechanosensory neural pathway mediating wet dog shakes

Abstract

Dogs and other mammals perform stereotypical rapid oscillations of their head and upper trunk to remove water and other irritants contacting their back hairy skin, a behavior known as wet dog shakes. The somatosensory mechanisms underlying this stereotypical behavior are poorly understood. We report that Piezo2-dependent mechanosensation mediates wet dog shakes evoked by water or oil droplets applied to the dorsal neck hairy skin of mice. A survey of mechanosensory neuron types that underlie stimulus-evoked wet dog shakes revealed that unmyelinated low-threshold mechanoreceptors (C-LTMRs), which form lanceolate endings associated with vellus body hair follicles and had been implicated in affective, pleasurable touch, mediate this behavioral response to mechanical stimuli. C-LTMRs were strongly activated by oil droplets applied to hairy skin and, unlike several other LTMR types, their optogenetic activation evoked wet dog shakes. Moreover, ablation of C-LTMRs attenuated oil droplet evoked wet dog shakes. Centrally, we found that C-LTMRs are synaptically coupled to spinoparabrachial neurons, and optogenetic inhibition of spinoparabrachial neuron synaptic transmission and excitatory neurons of the parabrachial nucleus impaired both oil droplet- and C-LTMR-evoked wet dog shakes. Thus, a C-LTMR-spinoparabrachial pathway mediates wet dog shakes to remove water and possibly other mechanical irritants contacting back hairy skin.