House training an adult dog can require the same procedures, and maybe more, as training a puppy. Bringing an adult dog into your home demands as much effort from you and your family as a new puppy would. It’s a common misconception to think that just because the dog is full-grown and may have been potty trained in one home 
that he’ll immediately adjust to your home’s schedule for walks, etc. also.
That’s not thinking realistically. The dog has to learn many adjustments in his new home and won’t instinctively know that you don’t allow peeing on the floor – especially if his prior owner allowed him to do so.
Don’t make the mistake of assuming that because he’s an adult dog that he’ll just “know” what to do. Start with him as if he were a puppy and gradually teach him the routine of your home’s pet potty schedule.
Steps To Take In House Training An Adult Dog
You may need to start with crate training or keeping him restricted to the bathroom or other, uncarpeted,. Then set a schedule for potty breaks. Adult dogs can be very picky about finding a place outside to do their “business” that’s apart from where they play, just as they don’t like to potty close to where they eat or sleep.
Fancy that…neither do we. 
Help him find that place in the yard or areas where you take him walking and return him there for future potty breaks. You have to monitor the potty breaks for several weeks to learn your dog’s elimination patterns.
You also have to set morning and evening feeding times. He may not have had such an organized life schedule, so this could take time for adjustment. Don’t believe that old saying, ‘you can’t teach an old dog new tricks.” It’s not the age of the dog that matters – it’s the consistency of the owner.
If your dog came from an abusive home, even if is was just filled with shouting and hitting with paper for any accidents, then your training efforts may take longer. First you have to win the dog’s confidence and understand that he needs time to get comfortable in his new home.
There will be accidents, so be prepared to clean it up and move forward. Don’t assume that an adult dog will be any easier to train than a puppy. Both dogs would face the same adjustment issues. You have to train with consistency and affection so that you reinforce the responses that you want repeated.
An older male dog may be accustomed to marking his territory by urinating on it. This is an instinctive behavior for male dogs – you aren’t going to break him of it without breaking his spirit or having him neutered.
House training an adult dog may prove challenging but it also provides the opportunity to bond with your new family member and the rewards are well worth the time and effort.