Dogs have a set of stiff hairs protruding from the sides of their muzzles that are popularly called "whiskers." These are not at all like the nonfunctional whiskers that men sometimes grow on their faces and they are technically called vibrissae.I have never cut them but Pippi was just cautious and wanted to avoid this. In the film below you may see why whiskers are so important and that cutting them may be harmful and painful as well. However, if you accidentally cut them off :
The whiskers will usually take a few weeks to a couple months to grow back. They grow just as the hair on the body does. So however fast her coat grows you can say that the whiskers will grow almost that fast but sometimes a little slower.justanswer.com psychologytoday.com
The vibrissae serve as an early warning device that something is near the face, and thus prevent colliding with walls and objects, and keep approaching objects from damaging the dog's face and eyes. You can demonstrate this for yourself by tapping gently on the vibrissae of a dog. With each tap, the eye on the same side of the face will blink protectively, and the dog will tend to turn its head away from the side tapped. The vibrissae also seem to be involved in the location of objects, and perhaps in the recognition of the objects themselves. Most animals use vibrissae much the way that a blind person uses a cane.
Harmful Effects of Cutting a Dog's Whiskers -- powered by ehow