Yes, a deer has roughly that long before going down. It takes 2 things to take down a deer and in both cases it comes down to the brain. If you take away the pump(heart), that send oxygen enriched to the brain, the brain will just plain shut down because of lack oxygen. The same thing happens to the lungs. If the lungs no longer have the ability to absorb oxygen, all the pumping in the world won't keep the deer alive. Even if you take out the liver or femoral artery, blood loss in the system is too low to maintain the brain with oxygen. Though a liver or femoral artery takes longer for the animal to go down, it is still very affective.