Have you tried to crate him > USing a crate will mean he has somewhere to sleep at night where he doeas,nt need a leash to keep him in place . And also a safe place to leave him when you go out you can get fairl large crates if you worried about room for the time your away . As he is 9 you could still have many more years to put up with this a friends shitzu did this as he got older sometimes you could say it was his age and he had less controll over his bladder but as your dog has always done it then that cant be the reason . Often marking is his way of telling you and others that this is his home , there are lots of other things you can do to make h im feel less of an alfa dog , such as reducing the amount of eye contact you give him and how much attention he gets too , Try ignoring him as much as possible dont let him jump at you when he greats you , when you reunite in the morning dont speak to him for at least 10 mins or untill he is calm and not looking for attention , then when you do fuss him its on your term and your time . this can be done also even when you have seperated yourself from him by going into another room , on being back in the same room ignore him till you call him and when he comes give lots of praise . Eat infront of him before you give him his meal even if its just a cracker an alpha eats first . and if he pulls on the lead when you got out stand still not saying anything untill he sits or is calm again and then resume the walk do this each time he pulls you may not get far to start but all hese ideas will forge you as the alpha not him and may make him less likely to mark . hope this helps .
Andrea

__________________