Sky Wolves by Livi Michael
Puffin Books ISBN 9780141319247
When Sam's aunt rescues a lost dog, Sam knows that something incredible is going to happen. Jenny the Jack Russell may be a stray, but she is no ordinary dog. Jenny is more special than Sam could ever imagine.... But Jenny is in danger, and now Sam, Jenny and a gang of fellow runaways face an extraordinary journey. The sky wolves are on their trail, and they won't stop until the rest of the world is destroyed.