My dog is 4 he came from the pound after he was found in the house and his owner had passed away, he was there for 4 days. When i go out and he is left alone, not usually for more than an hour he pees in the house. What can i do to help stop this behaviour?
As suggested before, get a crate and crate train him. Make sure it is big enough for him to stand up in and turn around. Make it a safe and happy place for him to be in (use happy phrases/treats/toys when he enters, etc).
Take him outside to potty after he has spent time home alone, even if he had an accident inside. And do the same if he has an accident while you are there. Take him to the same spot every time for a few weeks and use praise as he potties and treat rewards directly after he is done.
Never punish a dog for going inside because they may learn to fear going potty in front of you. If you catch them in the act, say a quick "no!" and take them directly outside and praise them for going potty outside. Again, take him to the same spot every time.
I would also talk with your vet because it might be anxiety or some other problem.