Well, some do. Hey wait! Are YOU looking for a cat or dog? Well, I can help you! This page has lists of websites that you can get cats, dogs, both, or one of them. I really want a puppy, but can't get one til my family moves to a bigger house! Waa! (lol) I never had a dog before, just a fish... Well, anyway, you didn't come here to read me blabbering about a dog i will not get for years. Well, I hope you enjoy the websites! I will keep adding them if I find some other ones. I try to find the best! Just click them to go to the web...
http://www.petfinder.com/index.html (This lets you find whatever pet you want!)
 http://adoptpet.com/(This one lets you get both cats and dogs.)
http://www.adoptapet.com/ (Get both, cats and dogs and even other animals!)
http://www.nextdaypets.com/ (Get a dog or puppy on this one.)
http://www.terrific-cats.com/for-sale/ (This one is obviously just cats.)
http://www.findapetonline.com/ (This one lets you find lots of animals incuding cats and dogs.)
More coming soon!