This is a crazy question, probably a stupid one too. Full disclosure, he's just a house dog, or more precisely a couch and bed dog not a hunting or working dog.
His name is Charlie, 5yrs he's about 65 lbs and a mutt mixed with healer, maybe some Aussie and lab. He's a good dog and a fun dog. When he was a late puppy, I'd say teens to early 2yrs he started yelping when any of our other dogs would brush against him, we found a spot on his lower back that was really sensitive. He's a playful guy, he likes to run hard and jump straight up and down as high as he can when he's excited about going outside or when he's stuck outside when mama comes home.
We took him to the vet, vet confirms the tender spot and does xrays. No problems with the spine and the hips are fine. The vet gives us some pain meds. Well they work and sometimes we'd have some left over for next time and sometimes we'd have to get more, but it was an on going thing for him. I didn't like that.
So one day after some youtube videos or maybe some animal planet show I decide to get him over to me and massage the lower 1/4 of his back. I looked for knots, kept direct pressure off the spine and tried to work the little knots I found down to the sides of his tail and his upper hips. It hurt a little but he let me do it, did I mention he's a good boy? So I did that a few times and he started feeling better butt we finished his meds.
Now warp 2 years later he hasn't needed meds for a long time maybe even since that first time I massaged his back. So honestly I'm not sure if he stopped hurting because of what I'm doing or because he grew into his fully developed size. But now for the last year or more, every time I sit down he comes and greets me, gets a little head pat, a proceeds to turn around and present me his back side for my job, a job which I love because I tell myself it helps him and he likes it.
I do wonder if he really likes it or if he does it because that's what we do whenever I sit down? Is there any way to tell?