1. Cornell Feline Health Center. Useful, trustworthy health information on a wide variety of topics from the first institute dedicated to promoting the health and well being of all cats: https://www2.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center
2. American Association of Feline Practitioners. Yes, it’s for veterinarians, but this site also has resources and educational material for cat owners: https://www.catvets.com/
3. Winn Feline Foundation. A great supporter of feline research: http://www.winnfelinefoundation.org/education/cat-health-library
4. Animal Poison-Control Sites. These two sites provide information and services in case your cat may have had exposure to toxic substances: http://www.petpoisonhelpline.com/ and https://www.aspca.org/pet-care/animal-poison-control
5. Tufts University Pet Nutrition. Useful, fun, and informative information from experts in animal nutrition: http://vetnutrition.tufts.edu/petfoodology/