We adopted a 2 1/2 year old coonhound about 3 weeks ago and he has been perfect. He's mellow, he's well-behaved, he's housebroken, and even after a week we have been leaving him out of his crate all day and all night.

Because we don't have a fenced in backyard, we take him on a minimum of 3 walks a day, at least about 15 minutes each walk, but the evening ones are usually longer. We also have a lead in the backyard, but he doesn't seem to enjoy that too much. For the past two nights even though we've given him plenty of walks and opportunities to go to the bathroom, he peed on the carpet while we were home the first night, and pooped close to the same spot while we were home the next night. Generally I've heard dogs do such a thing because they aren't getting enough attention or are upset at you, but we can't think of anything we've done that would make him feel that way towards us.

Could anyone give advice on to why all of a sudden after 3 weeks he did this for two nights in a row, and how we might correct it?

First have your vet check him for medical issues. A bladder infection or bladder stones might be the cause.

If everything checks out fine, give him an extra walk at night, before you go to bed. And crate him for the night.

Also make sure the area where he went is cleaned up good, use white vinegar or something that neutralizes the odor. Saturate the area with it. Otherwise he will just keep going there.

well we can't avoid accidents but we can still prevent it...

training also make a difference...