I've used supplements on older dogs, but never younger pups. In fact, because I've now had Yogi for 10 years, unless I'm mistaken (!!!!!), I'm getting ready to start him on Geri-Form, which is my own personal favorite older doggie supplement.
One thing you might consider is using Frontline, if you don't already. Frontline has cleared up many an ear problem for my pups with problematic ears, which means both Biscuit and Lady. I'm seeing the vet next Thursday, in fact, for my new pup because she's turning out to have ear problems. After that visit, I'll be putting the pup on Frontline to see if it's as effective for this pup as it's been for my others.
One thing you might consider is using Frontline, if you don't already. Frontline has cleared up many an ear problem for my pups with problematic ears, which means both Biscuit and Lady. I'm seeing the vet next Thursday, in fact, for my new pup because she's turning out to have ear problems. After that visit, I'll be putting the pup on Frontline to see if it's as effective for this pup as it's been for my others.