So, it is not just me that has a handle on my dogs!
Deer only stiffen up after they die, so forget about the “stiffen up” theory. They lie down because they are very sick or have reached a place where they think they can safely lie down. You don’t necessarily want to bump a wounded deer out of its bed but there are times when it’s a good idea to get on a wounded deer and stay on it. Certain muscle and bone hits produce bleeding which will lead to death if enough blood is lost. Pushing the deer can keep the heart pumping at an elevated level which can stimulate blood loss and work against blood coagulation and healing. The trick is understanding the type of wound you're dealing with. Keep the deer bleeding if the hit is not inherently fatal — this won’t happen if the deer beds, quiets down, and the blood coagulates. On occasion, pushing a wounded deer is your best option.
Getting on him right away can sometimes allow you to get another shot into him, too. I have observed many animals stagger about in an impaired condition before getting their wits and/or limbs working to allow them to flee and fully escape. Sometimes the backup shot is the one that does the trick.
8) Down is Dead:
Sometimes a deer shot with a rifle or shotgun goes down like a pile of bricks. The gun goes off and the deer goes down instantly, the hunter congratulates himself and does a little victory dance or some other foolish thing like pouring a cup of coffee or heading to the truck for lunch.
What the hunter should be doing is keeping the deer “covered” with firearm at the ready for a second shot. Instant “drops” are often the result of nervous system shock which can dissipate with time. The deer regains its equilibrium and is off to the races. Hits near the spine can cause this reaction and occasionally do. Be sure that deer is dead – all the way dead. The same goes for recovering “dead deer” who need to be shot again to prevent them from getting up and getting away.