We had an unfortunate event with Toby who is now 3.5 months. I noticed his upper left canine puppy tooth was broken-not just snapped off across but more shattered up to the gum line. Exactly when and how we don't know. I thought he had dirt on it but it turned out to be dried blood. We went to the vet just to be sure, thinking as a puppy tooth it will be ok, but we were wrong. He had to have a full anaesthetic and have the shattered remains cut out carefully, and even so his permanent tooth may be compromised--there was abscess inside near the bud of the adult tooth. He was in a lot of pain the first evening, but has bounced right back. We are softening his food and have removed all hard bones, shells etc from the yard. He is quite active and you would not know anything had happened. We feel badly that we did not catch it earlier---message here, check your puppy's teeth every day--and yes we were brushing!