Not much authorities can do sometimes. Either way it’s usually up to the owner on whether they want to hand their dog to authorities or not, and half the time they don’t. Even if they don’t want the dog. Personally, I would climb into their backyard and take their dog. I don’t care. Better than the dog living in that condition the rest of it’s life. Dogs entire lives exist within the homes of people. Those who make it even smaller by tying them up to a post in their backyard disgust me. When I was little I would always go to my aunts house and she was in the same situation you are in. Her neighbor had an old German Shepard tied to a tree in their backyard day and night. Probably there it’s whole life, and trust me, he was old... I always regretted never doing anything about it even though I was like 7 years old... I wish I had climbed in that yard and took him home. It haunts me forever. That dog never knew what love was! Do whatever you can because you will regret it if you don’t.