Do you or have you ever owned a dog who has/had hip and joint problems? If so, was there a treatment which seems to work the best for him/her?
We have been giving Mauser Joint Maintenance from Hartz. It's a daily regiment to help maintain healthy cartilage and joint mobility for dogs 50 lbs and under. I'm also giving him Hip and Joint peanut butter flavor wafers with Glucosamine. These wafers provide natural ingredients that support joint function and connective tissue to help your dog stay active and enjoy life.
We've been giving Mauser both of these for about a month and he seems to be doing better. He was at the vet, a couple of weeks ago, and he's hurt his back so we've not as active with him currently until he's feeling better.

Juni never had such issues since he's a small dog .. I think 30 lbs or something like that ...

I did hear that a lot of the big dogs can develop hip problems. I am glad there's such a medication to prevent this or ease their problems.

The only issue we had with Juni was some problem with the spine ... he had infiltrations and got better. No more issues after that "incident" ...

Glucosamine is all I have heard that helps some..If get hip dysplasia though may not work ..Just try to not work the dog to hard and keep from jumping to much..
Large breed dogs are to not start agility/jumping things till over 6 months as they are so prone to Hip Dysplasia.