When you get a new dog, after the excitement of welcoming the new member of the family, whether it's a puppy or an older dog, the first question that comes into your mind is "how do I train him or him?" (I'm gonna talk about "him" for the sake of readability, not a special preference, OK?)
Of course, if it's a puppy, it's very easy to teach him basic obedience and house training. But, how to train an older dog? You have always heard "you can't teach an old dog new tricks", but nothing can be further from the truth. The way to go about it is to approach it as you would when training the dog of any age. Most importantly is building a bond with your new pet. It's a crucial step to be able to train him successfully. You have to develop a caring and loving relationship with him to win his trust. Talk to him, go for walks (never underestimate the importance of walking your dog, even if you have it big yard for him to play in), spend quality time together, have play sessions, etc. It's very important to develop trust, but there also has to be mutual respect between you and your pet. It takes time to develop trust, and respect will come from defining boundaries and treating any breach with firmness and fairness. You have to develop limitations, in order to develop respect, and you need respect to develop a bond.
Once you have built a bond with your dog, training him or teaching him anything at any age, should be doable, but always keep in mind that training an older dog will not always be as easy as training a puppy. House training an older dog will sometimes take more time and will require a lot more love and patience on your part, especially if he was not house trained before, but it can definitely be done.
House Training an Older Dog
If your dog is urinating and defecating in inappropriate places, first thing to do is rule out any medical problem. It's always a good idea to have your new dog checked by a vet when you first adopt him. Sometimes even a diet change might do the trick. Being an adult dog, they might have a problem like incontinence, which is treatable with medications. Have a good talk with your vet about all the possible medical reasons for the behavior.
You must keep your dog in a consistent feeding schedule and remove the food one he's done. You must also take him outside on a consistent and frequent schedule. You should take him out first thing in the morning, last thing at night, and before being confined or left alone. A fully house trained older dog should eliminate outside at least four times a day. At the beginning, know where your dog is at all times. Watch for signs that he needs to eliminate, learn to read his body language. If you see him pacing, whining, circling, or acting restless, it might mean it's time for a potty break. If you don't have a chance to watch him constantly, you might need to use a crate or put him in a small room with a closed baby gate or door. Take him out every few hours, and as he learns, you'll be able to give him more liberty.
Whenever you take him out and he goes where you want him to go, praise him abundantly and even carry a tasty treat as his reward for going where he should.
What to do if you catch your dog in the act? Clap loudly or make a loud noise to startle him, but not enough to scare him. Avoid yelling or punishing him because if you do, he might decide that eliminating in your present is a bad idea, and find another place to do it. When you startle him, the dog should stop in midstream, then grab him and take him outside immediately. As you rush, do it gently and encourage him to follow you the whole way. When he finishes eliminating outside, reward him with praise and maybe a treat or two. If you find that he had an accident after the fact. Do not do anything to him since he won't be able to connect the punishment would something he did hours or even minutes ago.
Try to control your reaction to your dog's accidents. If you yell angrily and punish him you will jeopardize any bonding that you might have accomplished. Pet urine can be taken care of with an enzymatic cleanser designed for that purpose, it is not the end of the world.
If you can't get your dog outside quickly enough, maybe due to his age, or mobility problems, whether yours or hers, or if you live in a high rise apartment building, consider training your dog to eliminate on pads, paper or even a dog litter box.
Spread the word about older dogs. There are magnificent adults being left behind in shelters for the very fact that people don't know how to train an older dog and are afraid they are not trainable. They might be missing out on making a wonderful new friend