Brind and the Dogs of War by Christopher Russell
Brind is a kennel boy on the estate of down-at-heel knight, Sir Edmund Dowe - but Brind does not simply look after the highly-coveted pack of mastiff hounds. Found as a baby amongst the litter, he has grown up with them and is now more dog than human, with a particularly strong bond to alpha male - Glaive. In essence, he is their pack leader. When Sir Edmund takes the pack to fight in the Battle of Crecy, Brind's life is changed forever. Glaive, the only mastiff to survive the bloody battle, runs off; Sir Edmund is captured; and Tullo, the evil huntsman, is determined to bring shame on Brind and go back and claim the Dowe estate as his own. On his journey to reunite the household and most importantly, find Glaive, Brind befriends a feisty young French girl - Aurelie, who has her own agenda of revenge and keeps the adventure at fever pitch.