One can lead a puppy across these strange surfaces by placing the treat in front of its mouth, but not letting him have it until he steps on the obstacle. (cspca.com)
When they start to bite you make a fist and put it in front of their mouth and say NO in a firm voice. (love-springer-spaniels.com)
Puppies are generally born with no teeth, but baby canines» longer teeth on each side located in front of the mouth start to erupt between three to four weeks of age. (dogingtonpost.com)