Thanks, all! So far he's doing well... Boris is thrilled with him, and they are getting along famously. No issues between the dogs, not even with feeding them near each other (Boris corrected him gently the first time Ivan tried stealing a treat). He's gonna need some work with potty training, as he's peed on the rug a few times, despite having yard access with the dog door. Probably just a little stress and getting used to his new surroundings. He is also WAY too excited about the cats, but thankfully in a friendly way. I'm just supervising their interactions carefully, and otherwise letting them figure out what's what. I have been leaving them alone while I'm at work, with a baby gate to keep them confined to the downstairs room + yard. The cats have the whole upstairs to themselves.