(BTW, his dog was NOT sick prior to the trip. He didn't want to bother with the dog in the car. The dog got sick after riding on the roof for hundreds of miles)
Really? Because the story I got was that the dog was in the car and got sick with diarrhea (happens to dogs and cats alike - trust me I know) and THAT is when he decided he would rather have the dog on the roof of the car instead of in the car.
Never did I EVER once consider doing such a thing with ANY of the animals I have owned over the years. Having an animal get sick is just a hazard of traveling with pets...