puppy-dog book 

A used book (overall condition unimportant) that an avid reader "rescues" from a library sale, used-bookstore, clearance shelf, or home of a downsizing relative, without any immediate need for it but in the fear it will be pulped otherwise. The term puppy-dog comes from the similarity to rescuing an animal and taking it home to a house already full of cats and dogs, for fear it would otherwise be euthanized.

"Did you really need to buy DISCOURSES ON LIVY by Niccolo Machiavelli?"
"Well . . . it's a puppy-dog book to me. It's a good clean copy, it was cheap, eventually I may find time to read it, and most of all I couldn't bear the idea of it hitting the recycling bin and sent to print heaven."

puppy-dog book by al-in-chgo August 4, 2016