( quote One theory I have heard is that with a high heart shot it sends a pulse wave of blood up the main artery to the brain cause instance black out and then death, whether this is true I donít know may be our vet could comment.
If a high heart shot is used it can cause massive trauma to the main blood vessels such as the aorta and vena cava, once this happens a almost instant drop in blood presure occurs followed by unconciousness and death. In a low heart or purely lung shot the haemorraging takes longer and therefore the animal can run, further if adrenalised. end of quote )
I have moved the question from Thar and Mack to the Deer Welfare Section so it doesn't get lost.
Physiology of the heart. Heart muscle has the inherent capacity to beat itself which is modified by nerve and hormonal control amongst which is adrenaline.
A shot hitting the top of the heart when the top chambers are full destroys them and most of the connecting blood vessels : loss of blood. This gives hydrostatic pressure back flow and little or no blood gets through to the lower chambers , hence they beat on empty and no new blood is pulsed around the body. no blood no connection.
Shot hits when upper chambers are empty. all the blood is in the lower part ready or already down the arteries so no new pulse following.
A shot in the lower chambers makes a hole. When these are full large hole: more blood escapes. When the muscle contracts smaller hole: less blood escapes and some goes up the arteries but there is still blood returning to the heart. So the brain still gets some oxygen until not sufficient blood in system.
A condition called muscle memory comes into play. This is actually a misnomer. What really happens are the nerve pathways to the muscles are honed to perfection. So creating a super highway: extra fast response. So dying but still able to move.
Catching practice in cricket is to build up this muscle memory so that fielders react immediately to a chance of a catch.
Dropping on the spot after every shot. Unfortunately the spot the animal drops on is not always the position it was on when bullet strikes due to muscle memory but that is another story.