What to Do When a Puppy Starts Losing Teeth. Both Dr. Bannon and Dr. Reiter recommend letting the baby teeth fall out on their own, and advise against trying to pull loose teeth out. The teeth have very long roots, Dr. Bannon says, and pulling a tooth can break a root, leaving part behind and leading to an infection. However, something does need to be done in cases of retained deciduous teeth, where the permanent tooth is coming up in the same space that a baby tooth is still occupying ...