Puppies are known for being voracious chewers. This is because they spend several months teething as permanent adult teeth erupt through the gums. This is an uncomfortable process, during which your puppy may have tender, swollen gums, a slight fever and a decreased appetite.
When your puppy is around 3 months old, he will start losing his puppy teeth or deciduous teeth. These temporary teeth fall out just as the adult or permanent teeth begin to grow into place. The entire process takes a few months; by the time your puppy reaches 6 or 7 months of age he should have lost all of his puppy teeth -- toy breeds often take a little longer. Your puppy's central incisors, or small teeth in front, are usually the first to fall out, followed by the canines, the premolars and finally the molars.