There is a lot that goes into building a lethal bowhunting arrow, but ultimately nothing is more important than shot placement when shooting at game in the field.
June 14, 2022
By Jason Snavely
Sitting down to write this column for “The Shooting Issue,” my mind immediately focused on the science and physiology of a successful bow kill.
Throughout this series, I’ll discuss shot placement and the potential physiological outcomes of various “hit locations.” It’s my hope these columns will help you avoid heartache and the waste of a precious wildlife resource we all value so greatly.
No one I know understands the lethality of arrow-inflicted organ injuries better than Starkville, Miss., native and retired surgeon Dr. Joe Bumgardner. Bumgardner practiced abdominal and chest surgeries for 30 years and is an avid, lifelong bowhunter. He has also assisted Mississippi State University by lending his medical knowledge to a number of deer research projects. Perhaps even better, Bumgardner enjoys applying his experience from the ER and OR at the skinning shed, where he has inquisitively studied the cause of death for countless bow-shot whitetails. The skillset Bumgardner offers in educating fellow bowhunters is truly one of a kind, and I was fortunate to have the opportunity to pick his brain for this column.
Bumgardner is quick to credit two of his colleagues, and trained pathologists, for allowing him to submit tissues from harvested animals for processing in order examine the damage done to each respective organ after a broadhead-tipped arrow had passed through. He was able to correlate how mammals reacted to various archery injuries and ultimately define how that damage determined the overall demise of the animal. He sought to relate his human understanding of injury to that of hooved mammals such as whitetails, elk, wild pigs and antelope. In doing so, Bumgardner explains the primary classifications of death that result in punched tags.
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Causes of Death Shock and organ failure are at the top of the list when it comes to causes of death for bow-killed whitetails. The body maintains a very strict state of homeostasis between the circulatory (blood flow) system and the ventilation (breathing) system. An arrow sent downrange can strike the vitals of a whitetail and affect one or both of these systems. A heart shot is an example of a wound that affects the circulatory system, while the double-lung shot is the classic example of a fatal wound to the ventilation system. A combo shot — hitting both lungs and the heart — will of course result in death.
The tiny bubbles visible in this blood at the site of impact on an Ohio whitetail are a telltale sign of a lung hit. If you make a marginal shot on an animal — perhaps in the carotid artery or jugular vein in the neck — bleeding occurs but there’s nothing wrong with the animal’s ventilation system. As they bleed out. There’s a mismatch between the ventilation, which is still 100 percent, and the circulation, which is failing. This mismatch results in shock.
Hemorrhagic Shock Bumgardner notes the most common cause of death with archery equipment is hemorrhagic shock (blood loss), on an acute basis. “Acute hemorrhagic shock refers to the 3- to 30-minute timeline until the animal loses enough blood to cause shock and ultimately the demise of the animal,” he said.
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Bumgardner went on to explain how much hemorrhaging is required to cause shock. “When you hit a vital organ,” he explained, “the animal must lose approximately one-third of its normal circulatory volume to experience shock. Hemorrhagic shock occurs when there is enough blood loss that the circulatory system can no longer supply sufficient oxygen to meet the demand of the vital organs.”
A deer that loses enough blood will experience cerebral ischemia, or blood loss to the brain, and will begin to wobble or run into brush or trees. This bloody mark on the side of a large tree trunk was made by a disoriented Kansas buck shot by Editor Christian Berg last fall. Needless to say, the buck expired only seconds after crashing into this tree! According to Bumgardner, a mature doe has about 1 ounce of blood per pound body weight. A 100-pound doe has approximately 3,200 CCs of blood volume. If that doe loses 1,000 CCs, or roughly one liquid quart of blood, it will become immobilized. Keep in mind not all this blood will be on the trail, as some or even most may be maintained internally based on the location of the entry and/or exit wounds. A deer that has lost this much blood will exhibit cerebral ischemia, or blood loss to the brain, and will begin to wobble or run into brush or trees. Likewise, if a 200-pound buck, with 6,400 CCs of blood, loses about two liquid quarts, it will experience the same demise.
If you hit a deer in the “vital zone,” the heart and lung region, and your arrow passes through both lungs, you’ve got both lungs collapsed (bi-lateral lung collapse). “When both of those lungs collapse, it is a 100 percent lethal hit,” Bumgardner said.
Spinal Shock Another form of shock, caused when a bowhunter hits an animal in the spinal cord, is referred to as spinal or cerebral shock. There are two different outcomes when an animal is shot with an arrow in this region. The first occurs when an arrow hits the animal in the spinal cord. In this case, the arrow penetrates through the vertebra and transects the spinal cord, resulting in an injury that is irreversible. A bowhunter should follow up with a second shot in the vital zone.
However, if we hit close to the spinal cord and vertebra with an arrow, without transecting the spinal cord, your shot can result in temporary dysfunction. If you’ve ever shot an animal that dropped immediately only to get back up and run off, you’ve experienced temporary spinal cord dysfunction. In this case, you did not transect the spinal cord but instead the energy from your arrow merely transferred to the spinal cord, causing the animal to fall to the ground and remain temporarily paralyzed. The transferred energy causes temporary neurologic spinal cord dysfunction. As a result, whenever you make a spinal shot, always follow it up with a second, more lethal shot to ensure your animal does not get away.
In parts two and three of this series, I’ll detail what occurs when the dreaded gut, or paunch, shot is made and how to make the best of that difficult situation. I’ll also address the single-lung clot, shot placement, animal reactions to the shot and the biology and physics behind determining the minimum kinetic energy required to pass through a whitetail.
