I'm wondering if our nearly 13 year old boxer-lab cross is showing signs of dementia. He's been house trained for years and only sometimes made a mess when stressed during house moves and new baby. Lately on a few occasions he's just weed in front of us. Didn't ask to go out and been in and out all day. Just stands there and wees. It's like he's forgotten he's house trained! He's still his usual happy chappy self and was fully checked out as totally healthy a couple of months ago when he had an op. Could this be the start of dementia? What else could explain it?