Found: Horror/werewolf?

I'm trying to remember the name and author of a book. The plot was a teenage boy (I think was called joey) parents got killed, dad got trampled by a horse and mother fell off a cliff. An aunt comes to look after him with her two children a boy and a girl. Joey? Was really good with animals and had a pet dog went everywhere with him, nearby on a campsite a couple of campers get killed, slashed up, the local sheriff starts to think joey? Has killed his parents and when Joey runs away from home he tracks him in the mountains, where a snow storm hits and the sheriff nearly dies. Anyway it turns out Joeys real dad is living in the mountains watching joey, who is some sort of werewolf, joey discovers he also has the bloodlust and story end with joey living in the mountains with his real dads wolf. Hope someone can help Bo idea in author or year published, I know the story is set in America. Thanks

Solved. Book was called guardian by John saul

Touchstone: Guardian by John Saul

>3 lowelibrary: thanks, it's been driving me crazy.