The bones of the new story What Pet Should I Get? were found among the late TheodorSeussGeisel's orphaned art, imaginings and other creative work by his widow Audrey and an assistant.
The two had first set the documents aside after the death of the famed children's book author and illustrator in 1991. They rediscovered the material a few years ago, and now, with the help of former collaborator Cathy Goldsmith, have completed the book.
It's believed that Seuss — who apparently tinkered on several ideas at the same time — created the story and illustrations, labeled "The Pet Shop" in a folder, between 1958 and 1962.
Former designer and art director Goldsmith began working with Seuss in 1978 and helped him complete work on his final book in 1990, Oh, the Places You'll Go!
Now vice president and associate publishing director for Random House/Golden Books Young Readers, Goldsmith was tasked with painstakingly assembling and completing the Pet Shop book.
The new story centres around the siblings from Seuss's One Fish Two Fish Red Fish Blue Fish. It follows the brother and sister as they are overwhelmed with choice at a pet store.
Random House is anticipating blockbuster sales for What Pet Should I Get, with the publishing house increasing the initial print run to one million copies from 500,000.
Seuss's books remain a favourite worldwide, having sold 650 million copies around the globe. What Pet Should I Get? will mark his 45th book.