responsibility for his dog

Martin hunched his shoulders and tried to wrench his mind onto another track. Over a year now since they'd taken his dog from him, that big, wild-hearted puppy he'd named Rufus, and had owned such a short time, but had loved more than anyone or anything else in his life. They'd told him he had to take responsibility for his dog and warned him what they'd do if he didn't and he hadn't and they had, and he still thought it was the unfairest thing that had ever happened to anyone.
-- The Explorer of Barkham Street by Mary Stolz