The one thing I've noticed about Cardigans is... well, they talk. Far more than the Pems. They just vocalize about everything, talking to their toys, their food, other dogs, themselves, the air. They warble, gurble, mutter, whisper, snort, and a thousand little other words. I think it's like some secret Cardigan Language. Simon and Caleb seem to understand it (they're chattering at each other right now while wrestling in the corner) but Riley and Piper just eye them as if they've lost their minds.
It's interesting. I wonder if they have a Rosetta Stone Program for Cardi. ;)