My neighbors dog badly injured my cat?

It's been snowing pretty hard where i live and our outdoor cat was gone for about 4 days and he usually does fine in snowy weather. My family was really worried and thought he was gone but he came back and was in horrible shape. He couldn't open his eyes and his face was all swollen really badly. It looked like somebody kicked him really hard in the face. We brought him to the vet and she said that he was bitten by a dog and if his skull is fractured he'll die. The X rays showed that his skull wasn't fractured thank god but hes gonna be blind in one eye and the surgery he went through made his whole face bloody and raw. He didn't look good when he came back. My little sister started crying when she saw him. I've seen this dog tons of times before and the thing attacks almost everything that it sees. It even bit the Owner's son on the hand and the thing was going to get put down but the guy said he didn't want it put down probably because it wasn't even his son and since his wife is a tool she just listens to whatever he says like a puppet. Anyway, is there any legal action that could be taken from this? I should know before i start beating the **** out of that dog with a baseball bat until it stops moving.