hardly any muscle on back legs (GSD) Health

Glad to hear that the vet thinks he's fine.

Just wanted to comment that according to the hydrotherapist I use, most dogs don't use their back legs much for swimming - more just for balance/direction. So whilst swimming is generally good exercise, it might not meet your specific needs. Anyway, if you do take him, watch his back legs and judge for yourself (if the water is clear enough ).

I couldn't agree more, especially the longcoats, they all look like greyhounds when wet! I even said that to my vet once when he commented that Georgie was overweight, I answered with the comments that he looks sooooo thin when wet, to which he laughed his socks off and said that was a first!!

I actually had the very opposite with my Cassie, she had great big bulging out muscles on that part of her leg (hard as rocks too!) on the inside high up like where you are holding in the pic, and when she had an injury once and I took her into the vet, he diagnosed a hamstring injury because of the bulging muscle that side, but he never thought to feel the other side which was just the same! When I told him to have a feel a couple of years later and they were both like that, he said he had never seen such muscle on a gsd, but of course, she rode out with me on the horse and I biked with her most days too, so it was hardly surprising. They went to absolutely nothing though in her later years, no muscle there at all, it really does make a huge difference when they're very active I can say that much.

All my GSDs have used their back legs for swimming as well as their front. Even my boy who is virtually off his back legs with DM uses them when swimming though not as vigorously as he used to. He's the only one I swim as therupy the others have all been swum as part of their fitness for the ring.
Am having problems at the moment with people tryig to make me fatten up my bitch who is completely out of coat after her litter. I've made that mistake before. When she's back in coat the same people tell me she's too fat yet her weight stays the same.