A third method of correction is to use your fingertips to apply pressure on top of the muzzle or even use them to close the dog's mouth. (americanshihtzuclub.org)
Should be long, strong and deep right to the end of the muzzle, but not coarse. (akc.org)
In mandrills, dominant males have brightly coloured swellings on either side of their muzzles to display their status. (sciencedaily.com)