IMHO it very well could be ONE of the reasons why he's marked the door! If he is mature and smells another male dog, he is just marking to say HEY, THIS IS MINE! LOL. From all that I've read neutering doesn't always stop them from marking or even wanting to mate with a female. I just got Mojo done about 2 weeks ago and we think he is around a year. He is still squatting and hasn't marked anything that I know of, he has started to shuffle after he potties and this is a sign of dominance and territory marking too! I've also read that in a mature dog, these things can last for a few months after neutering until the testosterone levels lower in his system, so he may stop marking, shuffling, etc yet. You can also train him to not mark inside, just like potty training. Catch him in the act as much as possible and take him outside right away. Same basics as potty training. I hope Mojo never lifts his leg and can only hope even after his being neutered. I wish you luck!
