Kids may be indecisive about choosing a family pet, but they’re apparently mobilizing without hesitation to buy Dr. Seuss’ long-lost book, What Pet Should I Get?

In fact, with 200,000 copies sold in its first week on shelves, the title has become the fastest-selling picture book in Random House Children’s Books history.

What Pet Should I Get? launched in North America on July 28, and it has also broken US industry records across all picture-book titles for this year.

The book, which promotes pet adoption and animal care, features the brother and sister characters that Seuss first introduced in One Fish Two Fish Red Fish Blue Fish. Believed to have been written more than 50 years ago, news of the title made headlines in 2013 after the widow of Theodore Geisel (Dr. Seuss) discovered the original manuscript and illustrations.

To mark the book’s publication, Random House and Dr. Seuss Enterprises have launched a social media campaign that will support the work of the American Society for the Prevention of Cruelty to Animals (ASPCA).

The social marketing campaign calls for pet owners across the US to share a photo of their pets, tagging it with the #whatpet campaign hashtag. For every photo shared on Twitter or Instagram with #whatpet, Random House Children’s Books and Dr. Seuss Enterprises will donate one dollar to the ASPCA, up to the first 15,000 photos.

A landing page at www.WhatPet.com will aggregate all appropriate posts with the #whatpet hashtag from Twitter and Instagram.