The canine vibrissal system as a highly innervated and functional sensory organ.

Little is known about the importance of the vibrissae in domestic dogs and no studies have been published to date. The shaving of the vibrissae is still common in dogs, particularly in preparation for dog shows. In this publication, we show how dogs use their vibrissae with 17 video clips from 11 individuals. We also performed histological, transmission electron microscopic and immunohistochemical analyses to characterise the histomorphology of canine follicle-sinus complex (FSC). Tissue samples were taken from six dog carcasses. The videos show that dogs respond to mechanical stimulation of their vibrissae. Touching the superciliary and mystacial vibrissae induces a reflex blinking of the eyelids. Dogs also move their mystacial vibrissae forward to explore objects. Histomorphological and ultrastructural analyses confirmed that canine mystacial FSCs have the typical general histomorphology of mammalian sinusoidal vibrissae with dense innervation and specific mechanoreceptor structures. The follicles of the small hairs on the upper lip also have the typical canine FSC structure and, therefore, can be identified as 'microvibrissae'. In conclusion, there is sufficient evidence to suggest that the vibrissae of the domestic dog are a functional sensory organ and should not be shaved for cosmetic reasons to protect the physical integrity of the dog.