Anyway, I managed to lose the thing almost as soon as I got it. Darndest thing; I was walking across the house with three games and my DS. Everything else made it safely but Nintendogs vanished. Today I found it again.
The puppy had found it first. It looks horrible. On the back there are two big areas where it's been chewed up pretty good - in a few tiny spots you can see the green chip (?) inside the casing. However, it wasn't bent out of shape and the little... read dealy at the bottom wasn't shredded, so I tried it.
Miraculously, it WORKS. Max, the boxer I got before I lost the game, was still there, although starving, thirsty and filthy. I fed and watered him, washed him and walked him and the game didn't lock up, so with any luck it'll KEEP working.
Those suckers are tough!