If your pet is injured or showing signs of illness, please contact your vet or the nearest animal hospital right away. Search the Yahoo! Yellow Pages for veterinarian contact information.
If you're looking for information about poisonous substances, the American Society for the Prevention of Cruelty to Animals (ASPCA) maintains an online poison information center that lists symptoms and preventive information (but not treatment) for common poison problems including antifreeze, fertilizer, plants, household products, chocolate, drugs, garbage, Teflon, etc.
If you suspect a pet poisoning you can call the ASPCA National Animal Poison Control Center for 24-hour emergency information (please note, there is a $55 charge for this life-saving service) at 888-4ANI-HELP (888-426-4435).