Instruct: Classify a review into positive or negative sentiment.
Query: Shelby's Barken Review

This wonderful book about Gary and his dog, Cookie, starts here. Cookie is a true leader and loves being a sled dog. Cookie has about three litters a year. In one litter, one pup did not live; Cookie would not let it go until five days! A while after that Cookie and Gary were teaching pups to be true leaders, boy or girl, just like Cookie by running on the Alaskan plain. Cookie started to limp. She had arthritis! The doctor said, " She would have to give up running as a sled dog!" Will Gary have to give up racing, too? You will have to read the story and find out. Gary, a main character, is obviously representing Gary Paulsen, the author. I recommend this book to all readers, because it is heartwarming.