Nov 05, · Most of your dog’s baby teeth should be gone by 7 months, but some of Matilda’s fell out by the time she turned 2. If your adult dog has a loose tooth, it could be due to rotting, like Matilda, or it could have cracked or loosened while they were chewing on something hard. What to Do If Your Dog Has a Loose Tooth The average adult dog has about a 3rd more teeth than his human equivalent. Adult dogs have 42 long-term teeth compared to 32 typical human teeth, not counting any knowledge teeth. Pups have 28 baby teeth, .