Um... I don't think you can get a horse on the PS2 version. But yes, you can buy a hamster. This is from the PSP version, so I'm not sure it's accurate. Go into Buy Mode and keep looking in the sections until you see a red cage on a stand or something. I forgot because I used to have a PSP but not anymore.
But I hope this helps! Here's a link:
http://wiki.answers.com/Q/Which_shop_do_you_get_the_hamster_cage_in_sims_2_pets
P.S: I posted this link to help you. If it doesn't help, please tell me. Thanks!
I'm now in love with the little "despicable" Minions from Despicable Me. I saw the second film a few weeks ago and loved it and now I adore the Minions as well. They're too cute! Who doesn't love Minions? And I might not have a new sig and avy up for a while since I'm saving Images to my 3DS Camera. Look on Examiner.com to read what they're saying in the first film's credits.