My second hound, Lola, had quite a strong, unpleasant odor. Like you, I thought it was ‘kennel’ smell. No amount of shampooing made it go away. She also had beautiful teeth but horrible breath.
After I lost Lola suddenly, I began to wonder if the odor wasn’t linked to some underlying illness. The vet never could figure out what happened, but her blood work at the end was completely out of whack.
My only suggestion is to get some blood work and urinalysis done just in case.
I pray it’s nothing a good shampoo can take care of.