When I visit my vet I noticed she always smells my cat's breath during the exam. There is a good reason she is doing this. A stinky breath once in a while is not cause for alarm but if your dog or cat has chronically bad breath, it could be a sign of a more serious condition. Call your vet if you notice one of the following.
An ammonia or urine like smell. This can be a symptom of kidney problems.
A rotten smell. This indicate intestinal issues or gum or tooth disease.
A sweet almost sugary smell. This often signals diabetes. You will also notice your pet drinking a lot of water and losing weight.