Nylon xl muzzle - education and training for dogs - accessories and accessories. Selecting the right muzzle for your dog: take the exact measurements of the dog. The muzzle should not be too tight. Place the muzzle on the dog. Place your index finger to check that the muzzle is not too tight. The dog should be able to pant and move its tongue easily. It is preferable to place the muzzle looser than too strong.