Have you considered getting an Xpen to put him in when you are not right there with him to show him where to potty? Also they make puppy training pads that have a hormone already on them. The hormone attracts them to pee on the pad. They also prevent your floor from getting wet when he does use the pad.
Sometimes taking a dog for a walk will help get them to empty their bladder and bowels outside. The activity gets the body functions working and you have automatic outside potty use.
Did you ask the previous owner what his potty and sleeping habits were? |