Silly, but do you add or find Vitamin C included in his food. I have given my dogs Vitamin C supplements as puppies and adult females over the years and have wonderful hips and joints (Toy, Medium and Giant breeds). Dogs produce their vitamin C via the liver, but he may be outgrowing the amount produced. I have been using Dogzymes Cran-Tri-C Cranberry and Vitamin C Blend 1418mg per Teaspoon for the last year and I really like it. Before I was giving everybody Vitamin C supplements in their food and all girls have been on a cranberry regiment for years (Really bad UTI in a Chow that was even on prescription food for a while) to fight UTI's. The CRan-TRi-C lets me get the cranberry and the vitamin c at the same time, I know it can be done cheaper, but they are very reliable and it saves me a ton of time. My two cents!She is on Rimadyl now still and has been..... she is slowly improving but they are still not 100% what the problem is. We know she had the luxating patella but that is vastly improved.. There have been a lot of possibilities ruled out for various reasons and Her case is now being reviewed by a bulldog specialist in Texarkana.. I should hear back the middle of next week on that.. I’m starting to believe that it must be related to the massive growth spurt that happened within 2months... no other dog breed that I can think of gains that much weight in such a short amount of time... it’s bound to stress your joints and bones. She should be leveling out now and I have her on many supplements.. she is not overweight at all, just very much the bulldog shape. I am praying that this is all it is..