A friend of mine has gums that bleed a lot and a severe case of bad breath. It’s so bad that it can be smelled from across a room. What is causing this?

My friend has bad breath so bad it stinks up an entire room. He brushes regularly but never flosses. Could this be the reason? He went to the dentist, has no decay, no cavities, yet his mouth smells like a sewer. ????????

Yorkie has started coughing exspecialy after drinking, and breath has realy got bad and realy can smell it wean he barks vet says hes drinking to fast and dogs have bad breath but it just started and denta bones dont help?

We recently switched from Natural Choice dry food for puppies to Science Diet and noticed a chance in her breath. It obvious that the cause is Science Diet just by smelling the bag and food itself.

Has anyone else noticed this?
Anyone have any opinions about Natural Choice dry food for pups?
Oh, I do give her canned food mixed in.