Dog in No Mans Land by Damian Kelleher
Billy is an under-age soldier who befriends a stray dog in France during World War One. When Billy left for dead in the blood-soaked trenches of No-Man's-Land, the dog, Scruff, comes to his rescue. But Scruff is soon in danger himself, being sent onto the battlefield as an ambulance dog. Will both Billy and Scruff survive the terrors of war?