I just got this muzzle ordered through my vet, it appears too small. My dogs distance between tip of nose and eye line is 4 inches (100mm) the depth of the cage is about 3.5 inches (75-80 mm) (see photo)
The vet said the large size suits Labrador,German shepherd etc.
I don't want him uncomfortable or even worse not being able to drink
But I also don't want him to chomp another dog when out in public especially a smaller type. I may change it for the extra large next size up unless this size is ok.