Long Beach (CA) Animal Hospital (dogs, cats, exotic animals) Extensive and detailed client information -- Choose a topic where it says "Medical Services" and click "Go"
Pet Web Library Mar Vista Animal Medical Center. Another very good source.
Internet Cat Club Feline Health Topics An extensive compilation of feline health and general links maintained by Karen Laurence for Internet Cat Club (ICC). An excellent source.
IVIS (International Veterinary Information Service) A NY-based non-profit organization founded in 1998 to provide "up-to-date, clinically relevant information to practicing veterinarians, veterinary students" and "animal health professionals" world wide. A simple free registration gives anyone access.
Ask Purina: Dogs Many topics in nutrition, behavior, health, puppies and other.
Blood Blood tests, venipuncture, WBC differential counts, etc.
Nutrition Hills Prescription Diet, etc.