1. Length - distance from the tip of the nose to the eye line in inches.
2. Circumference - circumference around the snout one inch below the eye line in inches, should be measured with mouth a little open.
3. Eye Line - distance from the eye line to right behind the ears in inches.
4. Neck Circumference - circumference around the neck right behind the ears and right behind the jaw (in inches).
5. Width - snout width in the widest part.
6. Height - snout height, should be measured with mouth a little open.
View also more detailed instruction of dog muzzle sizing.
