Teething in the puppy refers to the process of growing baby teeth (deciduous teeth) and ends with the adult or permanent teeth. The first baby teeth, sometimes referred to as ‘milk teeth,’ erupt from the gumline around four weeks of age. These teeth are small and very sharp. They may scratch the nipples, resulting in discomfort to the nursing mother. By about six weeks of age, the baby teeth are sufficiently painful to the mother’s nipples to cause her to begin to wean the puppies from the nursing process.