I would like to say that I had great success with chiropractic treatment for a large Siamese cat that i was looking after for some friends. The chiropractor I found had worked with many animals including horses. His prices were reasonable as well.
The overweight aggressive cat would bite, squirm and generally be miserable anytime we would want to pick him up. I get along with all animals, so this was quite unusual for me! I sensed he was hurting/uncomfortable, so even though my family thought i was crazy, i took the hurting cat to the chiropractor, and voila....after only one treatment, i could pick him up and he purred and looked happy. We took him for an extra 2 treatments after that. It was funny....the cat knew it was good for him and happily laid on the chiropracters bench waiting for his gentle treatment. Our chiropracter used the gentle retractor gun tool to align his back. I think we had a particularly good chiropracter. Needless to say, find one who has worked with animals!!!
I'm guessing, but i think the cat must have jumped off a high ledge at one point,...that may have been what twisted his back out of alignment. By the way, his general anxiety decreased quite a bit after the treatment as well.
If no other indication that a dog has arthritis, it could very well be a misaligned joint (hip, spine, etc.). Look for a chiropractor who treats dogs and/or vet who uses acupuncture. My dachsie was down in back hips and vet said to lock her in a crate 2 weeks! Insane! I took her to my chiropractor, she found a problem in the low back and treated it. My dog jumped up and ran in circles, took off running down the 40 foot hallway and back, squatted and peed. No pain and she was all perfect again. She never had the problem ever again! I have personally had miracle stories similar to that with acupuncture.