My dog has a nasty rotten smell in his mouth. He has always had it. He has been to the vet many times and has always been declared healthy. I have changed his premium dry dog food several times. What can I try?

Changing his dog food won't help his breath, but may make him sick. Stop doing that.

Honestly, you can purchase dental treats or toys for your dog, but they sell dog toothpaste, and you can brush his teeth.

I'm pretty sure almost all ogs have icky breath haha.

The older he is, the more likely having the tartar scraped off his teeth would help. Feeding the dry chow is a good idea. If he wolfs it down too fast without chewing it, slowing him down might help. Either spread it out on a cookie sheet or something, or put big rocks in his food dish. Either way keeps him from getting one big mouthful after another. Finally, start brushing his teeth. They make both tooth brushes and tooth paste especially for dogs. Even wrapping gauze around your finger and rubbing his teeth will help.

Don't feed Greenies or other consumable dental chews. Dogs choke on them. There are some nubby Nylabones that claim to help.