This is one area where i sadly had a lot of experience with Abbey. We used a herbal mixture that had her moving freely incredibly quickly.
In Australia it is called Canine Senior from Meadow Sweet, but I have since found several herbalists that work with horses and dogs who make it or very similar.The important thing are all the beniftial herbs. Contains,Devil's claw Nettle, Clivers, Kelp,Aniseed,Chamomile
Abbey also had a can of sardines every other day, which she loved. I think animals know what they need. She actually used to lie in our Chamomile patch. Seatone capsules, which is a greenlipped mussle extract and the Glucosamine and it's co-products as mentioned above.
Now the Herbal mix was amazing. When Abbey had her first extreme pain attack at about age 3.5 she would hardly eat. The Herbalist told me to sprinkle the green powder TBSpoon on her food. She ate all of it and the next day she barked for her food. She knew it was right for her. And greatly improved over about six weeks. She also had Bowen treatments(deep muscle therapy) and lots of swimming.And for over four years she did amazingly well. She went from a hardly able to move to a quick moving bulldozer. I hope you can find some help. And please let us know if you find anything else that may help in the future.
If I had listened to our vet we would have treated her for Hip Dysplasia, but I work in a Radiology Dept and the Doc's said it was juvenile Rheumatoid Arthritis and needed to be treated as such and not have surgery on her hips. Hence she also had the heart attack (at least we are pretty sure). Hope this helps you some, I wish you good luck in your venture, please keep an open mind, cheers Ronnie