Hi there!
I have a few questions to help me guide you in the right direction
1.) How much are you feeding Buster each day?
2.) Any treats, human food?
3.) What food did you have him on prior to the Nutro with glucosamine?
4.) Has he been to your vet to see if he is just overweight or has a medical condition that may be causing him to be overweight?
5.) Does he favor his rear leg all the time?
6.) How much exercise is Buster getting? Do you take him on walks?
7.) Do you remember when he started favoring his leg? Was it right after he had exercised? What was he doing?
I will be awaiting your response
Laurie