Every 3 hours may not be enough. I said that if my dogs don't *ask* to go out and they haven't been out in 2-3 hours I will send them out, even if it means waking them up. They often ask to go out much more often than that. It's 11:15 and they have been out at 7:30, 9:45 (after a nap) and are now asking to go out again at 11:15...
Get a cleaner (I like simple solution, i think it smells better) and clean up the carpets and furniture. Confine or monitor him at all times, taking many potty breaks. Teach him to ring a bell when he needs to go outside. If you do this consistently for a few months, he will figure it out. DO NOT rub his nose in it!
By the way, marking outside does not mean you have to allow marking inside. Loki was neutered at 6 months, before he even learned to lift his leg. He is house trained but he still marks when we go on walks outside. He just pees twice in every yard. Actually, a walk is a good way to housetrain because not only will he pee until he is completely empty, but he will be tired and take a nap for a while so don't have to watch him so closely. As soon as he wakes up, go back outside. If you fall into a pattern like this you will learn when he needs to go. Also, you don't mention if pooping is an issue but if he is fed on a schedule he will poop on a schedule which is very helpful too.
I also agree that you should hire a dog walker. That way you can reinforce training during the day when you are not there and give him a potty break. He will also be a lot less hyper in the evenings if he gets a good walk mid-day.
Finally, you are not going to win the argument of rubbing his face in it - not because we are a bunch of wimpy Yorkie owners, but because it's scientifically unfounded. You never want your dog to be afraid of you. I know you said you have trained other dogs that way, but those dogs probably would have been trained no matter what methods you used. Yorkies take a lot longer to train, although being 18 months old at least you are talking every 2 hours not every 30 minutes! There is no reason to make the dog hate you when other methods are MORE effective.
By the way, what is the dog's name? |