Almost all mammals have whiskers. Facial hair — which is nonfunctional for males of the human species — serves to change or enhance their appearance. However, other members of the mammal family depend on whiskers as an early warning system like radar and as a GPS to aid them as they navigate about in their environment.
The scientific term for whiskers is vibrissae, from the Latin word "vibrio," which means "to vibrate." Whiskers — unlike fur and body hair — are thicker, stiffer, longer and more deeply embedded into an animal's skin. When objects or air currents brush up against a whisker, it causes it to vibrate, stimulating nerves in the hair follicle. Dogs and cats each possess a heavy concentration of whiskers on their upper jaws. According to Dr. Stanley Coren, author of "How Dogs Think and The intelligence of Dogs," of the areas of a dog's brain that process touch information, almost 40 percent of them are dedicated to the facial region that includes the upper jaw.
The whiskers grow in rows along the upper jaws as well as above the eyes on cats and dogs. It should be noted that this is a sensitive region of a dog's body and the reason why dogs dislike being patted on top of their heads. The number of whiskers on dogs varies by breed. According to Dr. Mary Fuller, author of the article "What's the Deal With ... Whiskers" on www.vetstreet.com, most cats have 12 whiskers arranged in four rows on both cheeks.
However there are variations with whisker length, texture and number in such breeds as the Cornish Rex and American Wirehair which have short curly whiskers, the Devon Rex which has very few and the Sphinx — a hairless breed — which has none. Cats also grow whisker-like hairs on the backs of their front legs that can help them sense prey and climb trees.
Whisker breakage and gradual shedding are normal — whiskers eventually grow back — and whisker remnants are often found imbedded in carpets and furniture during house cleaning.
The versatility and purposes of whiskers are quite remarkable and include the following:
• As a measurement device. Whiskers aid animals when determining if they can fit through narrow spaces. This is especially important to cats or dogs when hunting for prey, as well as for search and rescue and drug detection dogs to be able to perform their tasks safely.
• Safe navigation within an environment. Whiskers allow cats and dogs to detect changes of air flow direction so they are able to move about in a dimly lit room and not bump into walls or furniture.
• Protection for a pet's eyes and face. Coren and the author of "The Cat Behavior Answer Book," Arden Moore, both describe a remarkable involuntary automatic blinking response to shield the eyes that occurs in dogs and cats when a facial whisker is barely touched.
• Indication of a cat's current mood. A content and relaxed cat tends to push its whiskers in a forward position. A defensive or angry cat folds its whiskers back and is saying "stay away!"
• Location and recognition of objects. According to Coren, most animals use their whiskers similar to the way a visually impaired person uses a cane. As a dog approaches an object, the whiskers are directed forward. Then they slightly vibrate as the dog swings his head to drag the whiskers across surfaces. This "whisking" behavior provides information about the shape and texture of surfaces near the dog's head. This is helpful because a dog's eyes don't focus well on objects that are close and his muzzle — nose — blocks his line of sight when searching for things near his mouth. The whiskers that point forward and downward provide information that helps the dog to identify, locate and pick up small objects with his mouth.
Please note that some professional pet groomers might automatically trim the whiskers off of dogs to give them a "clean," tidy appearance; however, whisker trimming might be detrimental to some dogs. Dogs with diminishing eyesight due to aging or progressive eye disorders become more dependent on the sense of touch from their whiskers to be able to safely maneuver within their home environment. Owners of visually impaired dogs mightwant to request that groomers not remove whiskers.
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Writer's note: Damp fall weather contributes to the growth of mushrooms, toadstools and other form of fungi in yards, parks and areas where dogs visit. Decomposing black walnuts — sometimes carried and dropped by squirrels — grow molds that can cause tremors and seizures after a dog eats them. To prevent ingestion of toxic molds, dog owners are advised to thoroughly and frequently inspect their property for black walnuts and all traces of mushrooms or other fungi and remove them promptly, as well as walk their dogs on a leash to avoid areas where toxic mold growth might be present.