Dogs have whiskers on their nose above the upper lip, chin, and forehead. If you trim them, it will not hurt them. However, they do use their whiskers as a sixth sense, so you might be limiting their ability to play or hunt for a while.
Dogs’ whiskers are called vibrissae. Their roots are three times as deep as ordinary hair and the whiskers themselves are twice as thick.
Whiskers are one of the ways dogs sense the world around them. They can feel air currents and dogs use that information to figure out the size and shape of nearby objects. They can also figure out how narrow or tight a hole is.
Whiskers also help protect dogs’ eyes like human eyelashes. If the whiskers are touched, they blink.
So you can safely trim your dogs whiskers (and they’ll grow back) but it might be like putting ear plugs in their ears or blinders on their eyes! There is no reason other than showing a dog to trim their whiskers.