What is the best way to housebreak a 3 year old..?

Training a dog is comparable to training children. There are those who do not believe in discipline (like your child), some believe time out works sufficiently. In your case you have an older dog with bad habits. You have to have a set routine. take the dog out at the same time every day. Take the dog out at mid day, take the dog out when you come home from work and before bedtime. And when you are not at home confine the dog to a area that is easy to clean. Here comes the hard part (discipline) when the dog has a accident in the home, he or she has to know that it is not alright. You constantly have to watch the dog. You literally have to catch it in the act or very soon after. You cannot wait hours later (the dog will forget the ociation). As soon as the dog make the mistake, you must get the dog and take him to the area where he or she committed the act. Put the dogs nose in it (make contact with the nose). Tell the No No No while the dogs nose is in it if urine or close to it if fices.Some train with news paper at this point by hitting the dog on the rear (does not hurt the dog) but it makes a lot of noise. I simply pop the the dog with my fingers on the tip of the nose while saying no no no. this will take time. Do not discipline the dog if you forgot to stay on schedule, by not taking the dog out (that's your fault). A friend of mine trained his shepherd mix by putting a bell (same bell that's on a counter at a store) at the back door. Every time he took the dog out he rang the bell. Now when the dog wants to go out he rings the bell, to let him know he wants to go out.