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.
Re: dogs with back problems, hip dysplasia & bad backs & sea salt - I have never heard of bad results.You need to know how much your salt dog needs. I suggest salting its food and giving it a water dish with no salt, one with 1/8 tsp per quart and 1/4 per quart.
My dachshund went down in the back at 5 yo. Vet wanted to do surgery but since I didn't have the money we crated him for weeks & he ended up bouncing back. He had always had chronic constipation-sometimes so bad I had him at emergency vet several times - not one time did any vet suggest this could be from a disc problem. (His back obviously hurt too bad to poop) Also no vet ever said anything about vitamin c. They had me trying pumpkin, fiber, etc. - none worked. I poured through the internet & found out about vit. C. Started him on 2000 mg Ester C a day. Been 4 years now & poop is fine & he's had no problems since. Now my 11 yo golden mix has been showing signs of stiffness (beginning arthritis) and I've started her on Ester C - she's already showing great improvement. Bottom line is I think Ester C is a wonder drug. All my other dachshund rescues are now on 500 mg a day just for preventative.