This is why I have always been such a stickler for air
This is why The Old Man told me, "Jack, if a dog can't give me a good hard hour, right off the chain, then I don't need that fukken dog."
You can last for 2 weeks without food.
You can last for maybe a week without water.
But you can't last more than a couple minutes without air.
The quickest way to test a dog's gameness, is to deprive him of the ability to breathe, and IMO more dogs quit to running hot than they do to pain or any other reason. If you have a dog who's running desperately hot, and who's on the bottom, you have a dog that will 99x out of 100 quit.
This is why super-athletic dogs, who can breathe, will 99x out of 100 beat the rest: they will be on top and they will NOT be running hot.
Jack