Neutering only stops the dog from making new testosterone through the testicles, the testosterone that is already in his blood is still working, so you won't see any relief from marking for at least a month, until the blood testosterone level lowers. While the testes make the bulk of testosterone, the adrenal glands make some too, and the amount varies considerably between dogs, and this is why female dogs have been know to mark. The sooner you can neuter, the less likely a male will mark because you aren't allowing the dog to reach puberty when these changes start occurring. I recommend cleaning spots with Natures' Miracle, and following directions carefully, you have to give the enzymes time to work. Also, taking him on walks and allowing him to mark outside and offering praise for this can help alleviate his biological need for marking. Even neutered dogs who never mark in the house will mark outside, and this might help discourage his marking in the house. If it's only one spot in the house, I wonder if you could construct some temporary barrier, so that he could not reach that spot? Also, I've read that some people recommend putting a dog's food and water in a spot to discourage repeated peeing in the area. You'd want to clean thoroughly first!
