Whitetail ATLS Part 1

Whitetail hunting is one of my passions in life, like I am sure it is for many of you. As part of this passion I read many articles on whitetail hunting and find it is a great way to keep the spirt of the hunt alive 24/7. Recently I began to notice a bit of a trend in some of the stories and also in those told around the campfire. We all know a great deal about whitetail strategy, archery and firearm equipment, whitetail habitat, and whitetail activities. What we don’t seem to know a lot about, or at least don’t talk much about is the inner workings of our prey, you know, what makes them tick.

We all talk about the rut, full moons, temperature, and light cycles. But no one talks about deer anatomy, physiology, and more importantly pathology. Yes, we know that the heart and lungs are encased behind the ribs within the thoracic cavity. The liver is just caudal to thoracic cavity in the abdomen. Sure the kidneys and spleen are there too… Wait does a whitet ail have a spleen?

By having a better understanding of deer pathophysiology we could go a long way to make ourselves better hunters. Let me give you an example. We have all made shots on deer that we haven’t been totally confident about. It happens! If you haven’t, someone in your camp hasn’t then you haven’t been hunting long enough yet. When you make that shot your next actions are crucial and can make the difference from collecting your trophy and having that gut wrenching feeling of wounding and not finding the animal. There is nothing worse than that. There is always a delicate balance between pushing the potentially wounded animal and leaving it overnight to be scavenged by coyotes or have your trail washed away by the elements. Here is where the pathophysiology comes in. As an example of where we often go wrong these are some quotes from stories in a popular Canadian whitetail hunting magazine. And believe me, I have been guilty as charged with using the phrase “I think it was probably a liver shot” or something to that effect without really knowing the implications.

“… I knew right away, it was a piece of leg bone and the deer must be hurt badly.”
“… The arrow flew for the spot I had picked, and then dropped into his chest, hitting him low… We had been hoping for pink lung blood.”
“we were all there at first light and the comment was made that with all the sign he wouldn’t go far.”
“to my horror, the arrow hit the animal far back in the stomach… Just as I stepped in there, the deer got up and ran.”
“I struck him good but it wasn’t a pass through, I could see my luminock sticking out of his side…”

I am sure many of you have had very similar conversations when discussing shot placement with your hunting partners and trying to devise a plan for tracking the animal. Our intent with this mini series of articles is to shed some light on the pathophysiology of some common arrow placements and what you can expect from your deer. Let us start with some basics, what is the blood volume of the average whitetail?

Basically a deer has about 65-70 cc of blood per kilo. Therefore a 200 lb buck = 91 kg = 6.4 L of blood volume Now we always comment “there is lots of blood on this trail” but how much is lots? A deer, much like a human, can lose up to 30% of its blood volume before hypovolemic shock starts to set in. For those keeping track that is almost 2 L!

The next things we need to know is the perfusion of the various organs. Heart and lungs are the best place to start. The cardiac output (CO) of the average deer is about 4.5 L per minute, meaning 4.5 L of blood move through the heart and lungs (2.25 L each lung) every minute. Once blood passes through the heart the distribution is roughly as follows; Kidneys receive 35% of the CO, liver 10%, intestinal tract 15%, brain 15%, and the 25% or so supplies the peripheral limbs and remaining organs.

With these kind of numbers in mind we can start to think of what type of injury will be lethal to a deer and approximately what amount of time it will take for a deer to bleed out for various shot placements. Now this is just a start because for the majority of critical hits to the vitals, the cause of death isn’t due to hypovolemic/ blood loss. But these are topics for my next posts so stay tuned!

– Whitetail Junky

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