Rescue Me! Stars Who Love Shelter PetsFrom Miley Cyrus to Robert Pattinson, meet the celebrities who took in once-homeless pets

CHRIS KLEIN

The American Reunion actor credits rescue dog Chief with helping him face his alcohol addiction. "He began to recognize the behavior shift in me when [I drank] alcohol and his behavior would change," Klein told PEOPLE. "Anybody that has a meaningful relationship with a dog will understand that the disappointment that I saw in his eyes, [it was] insurmountable."