Would you consider this animal cruelty? What should I do about it?

A relative of mine has an adult Maltese. He was fine while he was a puppy. He was very playful like a puppy should be but then she bought one of those big cage things and started keeping him in that cage all day and all night downstairs in this room where her husband did nothing but smoke cigarettes and drink beer. She did feed him everyday but bathed him when SHE felt like it. So you could smell him when you walk in the front door. And she hardly let him outside to get any exercise. I tried to take him off of her hands when she moved into another house but it didn't work out because he had behavioral issues from being poorly socialized so I gave him back because I didn't know how to handle a poorly socialized adult dog and I couldn't find any information on how :(. He only saw 2 people, my relative and her son. And now it's the same thing in her new house. Locked in the cage, in a baking hot garage, with his droppings on his feet, barking day and night, getting on everyone's nerves lol. Only she or her son can do anything about it because he either runs away, bites, or bark at anyone else and yet, they ignore him. So what should I do? I can't take him back since my mother said I can't have a dog now. -__-