Wild Life by Cynthia DeFelice (author) (US edition)

Erik’s parents are being deployed to fight in Iraq, so he is sent across the country to live with grandparents he barely knows. Erik staves off his loneliness by befriending a dog there, but when his granddad says he can’t keep her, Erik runs away with nothing but his new best friend and a shotgun… Can he fend for himself on the wild prairie? Erik must use all the fight and ferocity he has learnt from his parents to survive in this harsh wildernesss.