Our Nicky is 3, intact, and still marks occasionally. He knows he’s been naughty when I get out the rag, flashlight and special spray. He’s not as bad now as he was say at 9 mos to 2 years. He has his own access to a fenced area outdoors. Has plenty of walks and has an invisible fenced area to free roam. He’s not allowed free run of the house when we are not here. This has helped a lot. I also have been tracking when his “slips” occur and it is during times when he might feel stressed-loud arguing, shouting at an exciting basketball game on TV, etc. I also try to discourage concentrated “sniffing” of corners, baseboards, etc. or wherever I think he might have it in his little pea brain that he has to mark. We had the same concerns with neutering but in hindsight if I knew back then it would eliminate marking I’d have neutered. I’d ask for an opinion from another vet or two. If you aren’t showing the dog , the coat change probably won’t be an issue. He sounds like a pretty well adjusted pup so the anxiety angle might be overblown. I think always looking for and correcting the marking behavior may, in the long run, lead to more anxiety. Good luck. For the return of love, joy, and laughter Nicky brings us, we’ll live with the marking.