Pets start losing their baby teeth at approximately 4 1/2 months of age and are usually finished at 6 months. Dogs have 42 adult teeth and cats have 30. In some case the baby teeth are retained and may have to be extracted. This can be common in small or toy breeds. Daisy was in for her spaying and actually had two primary - baby- teeth extracted  - the canines. This will prevent crowding and trapping of food in between the teeth. She was such a good girl.