This is a classic from my childhood. I had to buy it for my son's reading assignment in school, but I could not help picking it up and reading it while he was asleep. Classic story which will play well with boys, at least from my perspective, but I suspect anyone who has fond memories of life on a farm with a dog as a child will like the book, too.
The violence in the book is the normal violence one would expect from encountering wild animals (hogs). I never found it disturbing and neither did my son.