What should I do for my duck?

my duck Leonard was attacked by my puppy, I wasn't home at the time, but I was told it was around 10:30 I think when my parents realized that my puppy was on top of him. he was just chewing on him, and he's really injured. Leonard is missing feathers on his neck and right before his tail feathers, and is limping. we bought some disinfectant spray and we're going to catch him and wrap it, but is there anything we can give him for pain or anything like that?