I own the PC sims 2 pets, and mac is exactly the same. I love dogs and cats, and in this game, Aspyr does a FANTASTIC job of graphics. In each sim household, there can be up to 6 dogs/cats or 10 sims and pets in a household together. There are many new objects and a new function: Create a Pet. In Create A Pet, you get to choose the breed of your dog or like building a sim, you can customize the tail, nose, eyes, ears, and body. You also get to choose markings like a white muzzle or spots or stripes. There are many different colors your dog and cat can be, and you also get to choose the personality of your pet.
To me, the best thing in the Sims Pets EP is puppies and kittens. They can breed! In each litter, there can be up to 4 puppies/kittens. It always varies from 1-4 babies. Like sim babies, you usually can't tell what they'll look like when older, but when they grow up, they'll be a cross between their two parents. I hope this helped- and for christmas this year, it is definitely worth putting on your wishlist.