My Sims don't age up at all. I hate dying Sims (Means I love them too much).
But aside from that, I wanted to age up my kittens using a cheat, but they're too cute to do so.
They're so amazingly adorable with my horse. And together.
I really like how they take care of themselves in the game. I'm not capable of playing multiple Sims that much, but the kittens are fine on their own.
Made some to cute to be true screenie's i'll post later in the screenie thread.
Also, I believe my (Human) Sim, just growled and barked.
(I don't have a dog though.)