Catch And Redirect

Neutering lowers the drive, but your supervision and rewards are what teach the new routine. The most powerful move is to catch the mark before it lands.

As soon as you catch that leg-lift, walk him outside to finish, and reward the second he marks out there.

Do this consistently and you rewire the routine: the urge to mark now points to the yard, not the couch. Reduced testosterone makes him more willing, but this catch-and-redirect habit is what does the heavy lifting.