The bunny and hamster are pet mods found in the mod section, you can see the mod directory put together by Xay and BayouBlonde for a complete pet listing here:
Virtual Families Pet Listing

Lots of great suggestions in here, you guys should consider posting them in the suggestions topic:
Virtual Families Suggestions

MoonStar, you can get the different pets (like the bunny and the hamster ball) here

Yes, it's pretty funny when they pass by their parents and don't see them!

Lyss, we were typing the same thing at the same time. *laughs*

Thanks. How do you use these graphics of the new pets?

Mod Instructions for both Mac and Windows can be found here.

Thanks. The cat images at which I was looking don't seem to be in a mod or a zip file or anything. Do I just download the image to image file of the game? Does it replace the current cat? I'm not sure the mod instructions will work with what I found.

You'll right click and save the image to your computer, then place it in the image file of Virtual Families. Make sure that the file name is correct. (should be pet_grid.png or something similar)