Morley Callaghan 
Luke Baldwin’s Vow [PDF ebook] 

A story of a boy and his dog and their adventures, which will appeal to the many children who are dog lovers. It is also a sensitive story of love and loss, and of making a new life for oneself. Luke is not yet 12 when his father dies of a heart attack, leaving him an orphan. Small for his age and something of a loner, he moves from the city to the country to live with his aunt and uncle. He is naturally homesick and grieving the loss of his father. His well-meaning and kindly aunt and uncle do their best for him; but his only real friend and comfort becomes Dan, the farm’s elderly, one-eyed collie. Practical Uncle Henry considers Dan useless now that he is too old to be a watch-dog and decides that Dan should be "put down." Luke, whose sense of dignity and loyalty transcend the practical, frantically tries to save Dan’s life, providing for heart-racing suspense as he makes his stand against the expedient world of adults.