The Dragon Stone

Arthur, the younger son of a minor British nobleman, receives vital help from Merlin and Arthur's dog Cabal, and survives a series of attempts on his life, in the process proving himself qualified to become Britain's new High King. The Dragon Stone is the first in the series of four delightful books for middle-school readers "relating the adventures and noble deeds of Cabal, King Arthur's dog, as told by Cabal himself".