American Association of Feline Practitioners
The AAFP is like the American Medical Association for cat doctors, and has lots of good information regarding feline health.
American Heartworm Society
Everything you ever wanted to know about heartworm disease can be found here!
American Kennel Club
This site has lots of good information regarding training, responsible ownership and finding a puppy.
American Veterinary Medical Association
This site is a good starting point to learn more about a variety of topics, including feline injection-site sarcomas and the latest subjects in veterinary medicine.
Association of Pet Loss and Bereavement
We have all experienced the pain of losing a pet. The Association of Pet Loss and Bereavement has set up this site for support during this most difficult time. You will find inspirational stories, grief counselling resources, hotline number and many other resources.
Choosing a New Puppy
This is a nice starter guide of things that you should consider when you are thinking about getting a puppy.
Plants Toxic to Animals, Introduction -- Vet Med Library, UIUC
A lot of information about toxic plants can be found here. You can search under common name or scientific name of the plant.
Anyone who has ever lost a pet should visit this wonderful site. It is a terrific tribute to our lost family members.
The Cat Fanciers' Association (CFA)
The Cat Fanciers' Association website has lots of pictures, as well as information on cat breeds, cat care, upcoming cat shows, and much more.
USDA Animal and Plant Health Inspection Service
The USDA maintains this website with information on a variety of animal health related topics, including the latest news on such things as Mad Cow Diseases, foot and mouth disease, and many other things.