Imagine if The Sims and Nintendogs made sweet, sweet love. The result would be... well, it wouldn’t be pretty. A big, polygonal mess. But with a bit of massaging and fine tuning, it would be this game - just a few steps above a big, polygonal mess. In The Sims 2: Pets, your sim takes the role of a veterinarian who, naturally, happens to be a pet owner.
So on top of the general maintenance normally required of a Sims game, you also have to take care of your pet, as well as diagnose and treat other people's pets on a daily basis.