The movie is about a killer which has kidnapped a boy who he kept as his cleaner for the victims he kills. Later you see that the boy has grown up and still are his slave and he is chained like if he wore a dog. If you know the title please help me thanks you!

The only one I can think of that sounds close is this Bereavement (2010) - IMDb (http://www.imdb.com/title/tt1100051/)

No it´s not that one but thank you anyway.

No problem. I hope someone comes along with the answer for you!

Chained (http://www.imdb.com/title/tt1989475/combined)?