There is always hope but the adage, "you can't teach an old dog new tricks" does have a kernel of truth. When humans are children, they are like sponges and can pick up knowledge and behaviors quite readily but it becomes much more difficult the older a human gets. In the same way, a puppy is generally readily trainable but as the dog ages, it takes longer to train him certain behaviors. By the given age of 9, he has had a half of a lifetime (or more) to fall into behavioral patterns. I'd certainly recommend getting a professional trainer at this point to attempt to correct the behaviors.

There is always a possibility but I think this case is a slim chance. He seems a bit too old and as you say, he isn't the most obedient dog. The time taken to get him in shape might me the remaining life that he has.

I'll also have second thoughts about starting a training regimen at this point. At 9, she could be too old for her breed. I lost my three mixed breed dogs even before they turned 9, and yeah, they lacked training, too, and were mostly undisciplined. However, they are smart and sweet in their own ways, and I gave them unconditional love, which also meant I tolerated many of their behaviors, just like may be how I am tolerating the idiosyncracies of my fellow human beings and vice versa.

I think it really comes down to the dog. Just like people there are people that never stop learning while there are others that are set in their ways. I do think that he might learn something but it will never be the same as teaching a pup.

Nine years is quite a mouthful in terms of experiences in the life of a dog which can make it look difficult to adjust to lifestyle changes. The good thing is that dogs have neurological pathways that facilitate fast learning through a behavioural response of positive feedback. It follows that if you repeat particular actions and then follow up with a reward when the dog obeys, this will inculcate a new skillset in the dog's life.

I suggest to heed a professional trainer assessment to see whether your dog is still trainable or not. Because I really can't tell, the old saying may be applicable, but every dog is a different experience regardless of dog breed. Go ahead and try it out.

I say it would be much harder than, say, training a new puppy, but with determination and patience, it will still be able to learn new tricks. There is still hope, so don't give up! Don't be frustrated with the dog, and give it treats whenever it makes progress, even if the progress is very slight.