[header] How to diagnose dental disease in dogs [title] Pay attention to unusually bad breath. [step] If your dog's breath is worse than usual, it could be a sign that your dog has dental disease. With dental disease, bacteria and infected tissue can exude a putrid smell once it has developed quite a bit. 
[substeps] Dogs can have bad breath for a wide variety of reasons. The key is to identify when the smell changes or becomes markedly worse.