Puppies begin to lose their baby teeth at about four months old. The baby teeth are replaced by permanent teeth, and while it is different for each breed, most dogs will have their full set of adult teeth by seven months.
Similar to when babies are teething, puppies experience significant discomfort while their adult teeth are breaking through their gums. They can become irritable and chew on anything that they can to relieve the pain. They may also experience a change in appetite and excess drooling. Most adult dogs have 42 teeth, including molars, incisors and the large canines that are used to rip through food.