The 300 Pound Cat by Rosamond Dauer; Skip Morrow (Good, 1983, Pbk, 32 pages, Avon Camelot Books)

Cover and pages have usage wear; inside is unmarked; back cover has a stain as pictured. ISBN 0380627450

William Cat begins life as a very tiny newborn kitten, but he grows and grows and grows, until Dr. Cat is called in to solve the problem.