All 4 of my shelties have had great teeth up until about the age of 12/13. At that point, their teeth decided they wanted to be bad. Shelby of course, died at 10, so not sure what her teeth would have done.
Until a year ago, Misty had fantastic teeth. Then she started getting more tartar and lost a tooth. Went to vet for her gumming the side of her mouth. When he went to look at her teeth, one seemed loose. He wiggled it and it came out in his hand. He put her on antibiotics. Slowly her teeth have gotten worse.
Other sheltie owners say it seems to happen w/ their dogs as well.
Love All Life, Thank You For Posting! :)