Anyone own a mini doxie? Personal experiences?

My sister-in-law's marked inside the house, even though he had been long neutered. He loved to play fetch, with a ball bigger than his head -- there was a hole in it so he could bite onto it. It liked company: it barked when you came over, and got upset when you left. It was crate trained and would retreat to the crate when things got too hectic. It would also den under their couch. It lived to be 17.