These books were suggested in an article by Susan Mayer MLIS in JAVMA, vol 232, No. 10, May 15, 2008: A librarian's guide to providing resources to pet owners.
Most people don't go to the library anymore, which is a shame. At the University Of Tennessee we had a special library for the Vet School and a great staff that helped in so many ways I couldn't begin to state them all.
Here are some books that will help you understand your pet better:
The Angell Memorial Animal Hospital Book of Wellness and Preventive Care for Dogs, Darlene Arden
The Pet Lover's Guide to First Aid & Emergencies, Thomas K. Day DVM
Complete Care for your Aging Dog and Complete Care for your Aging Cat, Amy Shojai
The Cat: It's Behavior Nutrition, and Health, Linda P. Case
Grieving the Death of a Pet, Betty Carmack