Both my cats have nasty breath...when they yawn its like aargh! I'm not sure whats causing it, I feed them science plan and Iams....the dry food stuff. There doesnt seem to be anything wrong with their health either!
Do you brush their teeth? If you don't you may want to give it a try.I brush Frosty's and there doesn't seem to be a problem with his teeth at all.
Maybe, in your case, it is the food or something else (I feed my kitty Purina One Growth and Development)
Its funny, Sugar has good breath-it doesnt smell like anything and Twinkie has fish breath and I took them both to the dentist and got their teeth cleaned but its just his breath, I guess some cats just have stinky breath but they both eat the same foods and everything. Just try cleaning their teeth with some cat toothbrushes and see if that works! :lol: