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Thread: Excessive Blood clotting post headshot

  1. #1

    Excessive Blood clotting post headshot

    Can anyone shed light on why it is that post headshot the blood seems to coagulate really quickly and to congeal to the consistency of wallpaper paste to the point that it wont flow the same as blood from a shot anywhere else on the body, logically there must be a biological explanation as it happens when other species are shot ?
    i have seen it with foxes and recently when called to humanely dispatch an alpaca

    Cheers

    Tikkat3

  2. #2
    It's an interesting question. There does seem to be variable responses to trauma and the clotting of blood. I've recently been involved in a study that required me to collect blood from freshly shot rabbits, and two bunnies shot in the space of a few seconds in the same place can have very different speeds of clotting blood. If you speak to vets who take blood samples - sometimes a cleanly taken sample can take ~30 mins to clot in a tube, and if there is more trauma there the blood can clot in the syringe during collection. I found when shooting the rabbits more clotting present when using the .17HMR compared to the .22LR - the increased trauma from the ballistic tip plays a role.

    I would suggest that when an animal is head shot the trauma is concentrated over a smaller area (the head). I would suggest in general the forces are greater and the activation of the clotting cascade is greater hence the faster and more profound activation of the clotting cascade. I also wonder if when we head shoot an animal we create a tunnel that the blood passes through - this potentially allows the blood to come into more contact with damaged tissue than a wound in the chest. Contact with damaged tissue further activates coagulation. Exposure to air promotes coagulation further (going to be a greater affect when bleeding externally from a head wound, rather than into the chest).

    Does that help answer the question?

    Section 161 of the Highways Act 1980 (England & Wales) makes it an offence to discharge a firearm within 50 ft of the centre of a highway with vehicular rights without lawful authority or excuse, if as a result a user of the highway is injured, interrupted or endangered.

  3. #3
    Curious. I've not noticed this and after reading Apache's response did a google scholar search. Most of the concern for human trauma relates to a lack of clotting factors (lost through bleeding) although there is some intravascular coagulation (DIC - complex subject, but rarely good news). Perhaps that's the difference, the chest shot animal bleeds out too rapidly for clotting to occur. It might also be due to the acid-base balance of the blood. A head shot animal will stop breathing and the acid base balance is upset, triggering more clotting. Apache's explanation could be on the right lines, the head trauma, if the heart continues beating will circulate an awful lot of tissue breakdown products, not least tissue factor that starts the clotting cascade. As the blood is still contained in the vessels, all the normal blood proteins will be activated. I'm not entirely convinced as most of the papers I've skimmed refer to a lack of clotting or the aforementioned DIC.

  4. #4
    I was speculating from first principals! I'm not sure DIC has any role in this whatsoever!

    Section 161 of the Highways Act 1980 (England & Wales) makes it an offence to discharge a firearm within 50 ft of the centre of a highway with vehicular rights without lawful authority or excuse, if as a result a user of the highway is injured, interrupted or endangered.

  5. #5
    Does it actually coagulate faster from the head or does it just seem to because there is less of it in one place?... Sometimes with chest shots you are scooping out great lumps of jelly, other times less so.

  6. #6
    I found much the same info Buchan, i was wondering if it was to do with the animal being headshot being "brain dead" whilst the body shot animal obviously isnt?
    i'm not convinced its to do with a "localised trauma" as i've seen plenty of animals that have bled out from a wound elswhere on the body but it is only headshots that i'm seeing this heavy clotting occur to the point that you can actually pick up a handful of it albeit like trying to pick up a splattered triffle, there must be someone on here with veterinary training that can shed light on this? if not maybe i might ask the BDS and post their response for everyones information?

    Tikkat3

  7. #7
    Quote Originally Posted by TikkaT3 View Post
    I found much the same info Buchan, i was wondering if it was to do with the animal being headshot being "brain dead" whilst the body shot animal obviously isnt?
    No. Clotting is independent of being alive or dead. The clotting tests are run in the lab from a test tube - citrate is used to temporarily halt the process. Hence the blood in a dead animal clots.

    Exposure of blood to tissue factor is vital for clotting. There will be more contact through a relatively small head wound than a large calibre that has exited.

    Exposure to air also increased the efficiency of blood clotting ability (hence external blood loss should clot faster than blood collecting in a cavity).

    They are absolute. Basic physiology.

    CSL may have a point with less blood more ability to clot. I'm not convinced that there is absolute consumption of clotting factors when an animal chest shot.

    Section 161 of the Highways Act 1980 (England & Wales) makes it an offence to discharge a firearm within 50 ft of the centre of a highway with vehicular rights without lawful authority or excuse, if as a result a user of the highway is injured, interrupted or endangered.

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