My dog luke

My dog luke was a victim of a hit and run right in front of my house. Luckily we were able to take him to the vet's office in time. We paid $750 on our credit card just to check his lungs and do x Ray's. They told us he should be fine and to leave him for a few hours for observation. They called us 30 minutes ago now and said his lungs are collapsing.  Please help us save my dog he the nicest dog in the world and we wont to save him. I was told the surgery might be more but I just want to be able to give anything for my dog to have a chance to live. Hes only 4 years old.