We were able to locate some information about allergic skin reactions in the The Merck/Merial Manual for Pet Health, Bruce Fogle's ASPCA Complete Dog Care Manual and Caring for your Dog. The website, www.petmd.com had a wealth of articles about dog allergies for our patron.
PetMD was also a useful source of information for our second patron. Our patron's description of symptoms matched some described on the website: "Your pet may be experiencing unexplained vomiting, diarrhea, or may appear to be weak (lethargic) to the point of being unable to move." There was some information about poisonous substances, but not a list that our patron wanted. We located additional websites for her which included: 24/7 Animal Poison Control Center run by ASPCA (phone # 800-213-6680); pets.webmd.com that has a list of the top ten poisons; and www.doctordog.com/dogbook/dogpoison.html that has "Dog Owner's Home Veterinary Handbook." This last site had the type of listing she wanted printed to take home.
Each book and website we consulted encouraged the user to contact a veterinary professional in order to correctly treat both allergies and poisoning.