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Posted by CAL on August 15, 2002 at 13:07:22:
In Reply to: Re: C.v.oreganus & toxicity posted by Blackwater on August 04, 2002 at 07:31:38:
:I remember reading about a Northern Pacific Rattlesnake bite (I can't recall the source) a few years ago that had symptoms of a neurotoxic envenomation, so I don't think "sweating it out" is a good plan.
:In short, ALL rattlesnake bites deserve respect. If you are bitten, you should make for the nearest emergency room without delay. You may be allergic to the venom, and anaphylaxis can kill you a lot quicker than the venom can.
:If the snake bites you and it doesn't inject venom, you'll be released from the hospital in a couple of hours. If it isn't a dry bite, you'll be in the right place to get treatment when you need it most. The current recommendation for field treatment is to immobilize the limb and transport the bite victim immediately. You can buy a "Sawyer Extractor" and keep it handy for use in the event of a bite, but the effectiveness of the extractor is the subject of great debate in toxicology circles. I have one, and I take it with me anytime I go out in snake country. I plan to use it in the event that I'm bitten by any venomous species.
:C. v. oreganus isn't particularly toxic when compared to some venomous snakes, but you never know how much venom has been injected in any individual bite. That is what makes the determination of the level of care that will be required, in any individual bite case, impossible to predict. The unfortunate reality of it is that the doctors are limited to doing a few preventive things (like steroid and antihistimine use) and then all they can do is react to the symptoms as they develop.
:I did a quick search for Ld50s (Lethal dose in 50% of bites) for mice and C.v.oreganus. I didn't have any success, but I did find some data for the "Western Rattlesnake" (Prairie as I call them). I don't know how reliable these data are, but here's what one site says:
:Crotalus viridis, LD50 1.01 mg/kg Venom yield (mg) : 35.0-250.0
:I doubt that an "average" C.v.viridis can inject 250mg of venom (dried weight), so I find these numbers to be a little suspect, but this is how I do the math in my head when trying to extrapolate how the snake would effect a human.... If the Ld50 is 1 mg/kg (roughly), and I weigh 100 kilos (225 lbs), then it would take about 100mg of this species venom to kill me in 50% of the bites that I receive. The next thing I try to decipher is, can this snake deliver that kind of yield in a bite?
:If we take the red pygmy rattlesnake as an example;
:According to Bryan Grieg Fry's data base,
:Sistrurus milarius barbouri has a sub-cutaneous Ld50 of 24.3mg/kg in mice. So if we had a 1 kilogram mouse, it would take 24.3mg (dried venom weight) of pygmy venom to kill that mouse 50% of the time. According to the Venomous Reptiles. org site, the average yeild for a pygmy rattlesnake is 20-30mg of venom, so that species shouldn't be life threatening to a human.
:I hope I haven't made this worse for you.... I'm going to attach a link for BGF's site, so you can go there and read about venom and what to do for a bite.....
:The bottom line is, if you get bit, get to a hospital and let them evaluate and treat as necessary. It's better to be there and not need treatment than to be somewhere else and in trouble.
: :I work in the field, and am in constant close quarters with northern pacific rattlesnakes. I am very careful, and always use caution, none the less a bite is always possible. I have heard that some people, when bitten, refuse antivenin and simply "sweat it out". Would there be a benifit in allowing your body to beat the toxin, rather that get antivenin.
::Also, what is the level of toxicity in relation to other crotalids? Any stories of C.v.oreganus bites? Thanks
:Just a question about the LD50. Wouldn't you have to devide your weight in half to get the correct dosage? By that I mean, it will kill you 50% of the time, but not all the time, what minunum dosage would kill 100 of the time. Thank you.