I looked at the "trial" version of the pet/mount guide and it seems to be categorized into feline, etc. Does the paid guide have a guide that takes you to all of the NPCs in the game that sells pets and buy them all? To me that would be a valuable start, and I can't seem to find anywhere that mentions how the guide is outlined with enough detail to answer my question.
The full version of the Pets guides does include all of the merchants as well as other pets obtained from quests, etc. It does not have a single guide to take you to all of them, but has them sorted similar to how it is in the trial guide where you'll have the different categories of pets that you then go into for selecting the guide to get that one (or more if it's vendor) pet.