Sawyer Extractor Snake Bite Kit – Still Relevant?

I post to all the rattlesnake ones because I was so freaked out after running into *5* of them in the Superstitions in one weekend that I contacted Bryan Hughes, a herpetologist who also runs Rattlesnake Solutions (they remove snakes and release them to natural environment).

He will tell you not to waste your money. The extraction process is simply not effective enough, if at all, to merit the time it takes to fiddle with the device – time which is now precious because you need to get medical attention (anti-venom).

May be over-reacting (okay, probably am), but I actually carry a Sharpie marker now to outline the perimeter of inflammation and note with time so the doc gets an idea of progression.

Now if you're out in the middle of nowhere, with no chance of timely treatment and nothing BUT time on your hands? I wonder if he'd advise fiddling with then.

> time which is now precious because you need to get medical attention (anti-venom)

So… forget the immobilization, just run like hell to the nearest ER? Getting anti-venom as quickly as possible takes precedence over keeping heart-rate down?

And (you knew this was coming) follow up question:

I can retrieve my Sawyer and use it in under 30 seconds (with little to no fiddling). The ER is a day's hike away. I shouldn't waste that 30 seconds on trying to extract?

The sharpie idea sounds like a good one, mind if I steal that.

Lol – I know. From what I understand, no running, but walking at a slower pace to prevent elevated heart rate. But again, if you're 50 miles deep, I have to think the extraction device would come into play as a last resort.

Damn it – I was doing so well not thinking about this anymore. Maybe I'll shoot him an email.

Ask Mr. Hughes to consider the situation from the perspective of a solo backpacker who's a day or two away from an ER. I suspect he's giving generic advice to the 99.9% of the population that's within 30 minutes of an ER.

Watch Venom ER and learn more than you knew existed about venom from snakes. + how many on the extractors and other snake bite kits being worth anything.

Stay calm and get medical attention ASAP. Don't put your hands or your feet where you can't see them. Be aware , but don't be paranoid. You pass way more snakes than you ever see. Oh and don't forget about scorpions and spiders.

Sweet dreams.

The basic plan is to stay calm and not increase heart rate. Assume the bitten area will swell up and so remove jewelry or clothing that might turn into a tourniquet when it does. Wash the bite with soap/water and splint it just below heart level. Evac has the priority over immobilization, so walking slowly out with rest breaks would be the way to go if there’s no other transport option. (Don’t use tourniquets, ice, incisions, sucking, etc.)

In terms of pressure immobilization (I think what you mentioned the ace bandage for), that comes from Australia where it’s effective against elapids (in the US, those would be coral snakes). The goal is to limit the spread of venom. Note that coral snake venom is primarily neurotoxic (affecting the nervous system) while that of pit vipers is hemotoxic (destroys tissue). Using this technique with a rattlesnake bite is more controversial because the now-concentrated venom will do more damage to the local tissue.

At least in my training the Extractor is not recommended, evidence suggests that it is able to remove very little venom, and/or may cause more localized tissue damage.

Edit: yes, marking the pace of the swelling is also recommended.

Bitten by a pit viper: 25% chance of a dry bite

1. What kinds of signs & symptoms are you likely to see as this wound progresses?

There is a 50% chance this is a mild to moderate envenomization.
S+S for mild:
1. pain at the bite site
2. swelling
3. area around bite turns black and blue within 30 minutes

S+S for moderate:
1. swelling both distal to bite and up extremity toward heart
2. numbness
3. swollen lymph nodes
4. formation of bleb
5. overall weakness in patient
6. nausea, possible vomiting

If this falls in the 25% chance of a severe envenomization, S+S include:
1. jump in pulse and breathing rates
2. profound swelling
3. blurred vision
4. headache, light headedness
5. sweating, chills

Some factors which influence how serious/dangerous the envenomization is include:
1. age, size, health and emotional stability of the victim
2. whether or not the victim has an allergic reaction to the venom
3. where the victim was bitten
4. how deeply the fangs penetrated
5. how “upset” the snake was
6. species and size of snake
7. the amount of venom injected

What kinds of treatment options do you have?
1. Make sure the scene is safe, stop any serious blood loss.
2. calm and reassure the patient
3. keep the patient physically at rest, with the bitten extremity immobilized and at heart level
4. remove anything which may reduce circulation from swelling (clothes, jewelry, etc)
5. clean the wound
6. mark the boundaries of swelling by drawing a line on the patients skin, also write the date/time. Continue to monitor swelling.
7. maintain body temp, keep well hydrated (watch for vomiting)
8. if can be done safely, attempt to identify the snake
9. Some things not to do: do not cut or suck the wound(includes extractors, no cold therapy, no tourniquet, no electrical shock

Preferred method of evacuation is to have the patient carried out. If this is not an option, slowly walk the patient out with frequent rest stops.

"Note that coral snake venom is primarily neurotoxic (affecting the nervous system) while that of pit vipers is hemotoxic (destroys tissue)."

I've read there's actually a ratio of both in rattlesnakes. Diamondback venom is mostly hemotoxic, while Mojave venom has a higher ratio of neurotoxins. I can't reference any peer reviewed journal articles, but maybe you'd know if that's true.

Anyway, I sent an email to Mr. Hughes, Dunbar. I suspect SOL lingers as an option, though – lol.

It's supposed to be awfully remote to get bitten. A percentage of bites don't "land," and a percentage of those that do don't actually deliver venom, and this after considering the percentage of encounters that would actually realize a strike attempt.

Until I can slip gaiters into the budget without my wife noticing, I hike in the Sups during Winter. :)

*Delmar* – my bad, not Dunbar ….

Another contradiction: “Immobilize the appendage and elevate it to heart level” and “slowly walk the patient out with frequent rest stops.”

Well…which? They’re mutually exclusive in a leg bite. I think maybe the contradictions indicate TKB is right: “SOL lingers as an option.”

I hike in areas rather similar snake-wise to TKB’s, and I’m thinking I might invest in gaiters, too. I already wear long pants no matter how hot it is.

To mix it up: This is a 2008 post from another thread, from Art Sandt:

“In the desert Southwest or anywhere you'll find a lot of aggressive venomous snakes, however, a snake bite kit is a good addition to your kit. People will say "oh, you don't need it, just go to a doctor, they don't work anyway, blah blah," but I've heard this line mostly from people who just don't have a lot of experience with snake bites in the backcountry. The fact is that a snake bite kit–particularly the vacuum syringe in the Sawyer kit I mentioned above–can remove some of the venom from a bite. Some. For snakes with hematoxic venom (the kind that kills your flesh), that counts for something! A lot of aggressive venomous snakes have hematoxic venom, which causes damage to your tissue relative to dosage, so the less venom, the less bruising/soreness/dead tissue/overall illness will result from the bite. Now I doubt the same is true for snakes that have neurotoxic venom (coral snakes for instance–a lot of Australian species also have neurotoxic venom). I think in the case of neurotoxins, no matter how much venom is injected, as long as there's more than a drop in your bloodstream you're pretty much screwed. However, I believe that most rattlesnakes in the United States have hematoxic venom so a snake bite kit is a good idea a lot of times, in the US at least.”

"I've read there's actually a ratio of both in rattlesnakes. Diamondback venom is mostly hemotoxic, while Mojave venom has a higher ratio of neurotoxins."

That is my understanding. I call it the Mojave Green. Since its venom has enough neurotoxins in it, the victim is likely to be psychologically altered enough that in the ER he might be diagnosed as a drunk or on a drug high. Coral snakes are so much easier, since their neurotoxin just kills you in a matter of minutes. Coral snakes don't kill too many people, because their venom is expressed from the back of their mouth. They have to find a flap of soft skin and chew for a bit to get the venom into you. That's why the victims are more likely to be drunk, unconscious, asleep, or unable to care for themselves, like a baby.

–B.G.–

The "heart level" bit is just to strike a balance between reducing swelling (as traditionally one would elevate the limb) and reducing the spread of the venom (keeping it below heart level).

If you need to walk, walk.

….takes hours to induce respiratory failure, not minutes. Also, there has only been one coral snake fatality in the U.S. in the past 40 years, and there is currently no antivenin available.

Okay, Delmar, here's the email response from Mr. Hughes:

"Things definitely get more difficult if you're more remote, but the extractor still would cause more damage than to do nothing at all. It's just a bad thing to do, not just the worst of several options.

If you're extremely remote, the best thing to do is to treat it as you would be to be mindful of where trails are. Even if you're near help, the goal is to be found if you're unable to help yourself. Don't take any shortcuts, the idea being that if you lose consciousness, you'd be found by someone. The rest remains true – try to keep your heart beat low, don't mess with the bite (cutting, sucking, tying off, etc), and just calmly make your way towards where there's any kind of foot traffic. It doesn't feel like doing the best thing, but in this case it really is the best course of action to do nothing and try to let your body fight it. Most of these situations are quite survivable, and are exceptionally rare. When I am working in remote areas (often with MANY rattlesnakes around me), I always note the closest, highest traffic area in mind. If you're on a trail where just 1 other person will pass along per day, and you can get to it before you collapse, you'll live. It will hurt, but it takes awhile to kill unless there's some other health issue going on.

I hope it helps!"

John, there is antivenin available for coral snake venom. The most recent batch was set to expire, yes, but the FDA extended its expiration date (again) to October 2014. They’ll probably extend it again, after more testing.

As for the extractor, here’s a brief lit review from the Annals of Emergency Medicine saying that extractors are worse than worthless.

A little off topic but how serious is a rattlesnake bite? Is it PLB/spot worthy of use if say you're 10 miles out or more or would you just walk until you found help (assuming you are on a moderately used trail)?

It depends.

If the rattlesnake gets a full load of venom into you, it could be lethal if you don't get any ER care. On the other hand, if the rattlesnake bites you without any venom, then it might not be worse than a bad skin wound. That is why the bite location should be watched very carefully for five minutes. After five minutes, if a serious dose of venom is in, the victim or the watcher will know about it. It should take you less than five minutes to apply a constricting band, and that should slow down the movement of any venom.

At the five-minute point, you should know whether to call for help or not. One problem would be if you try to walk out on your own, and then you pass out.

If you thought that you could get emergency help to where you are, the outcome is more predictable.

–B.G.–

Ten miles out I would call for evac, absolutely. One of the big problems with hiking out is that you can't really avoid elevating your heartrate, which speeds up the poison's action. While a venomless bite is possible, all the medical advice I've seen says to treat every bit like a venomous bite because you can't always know, and the time it takes to find out is wasted time.

Let's put it this way. If you call for rescue in event of a rattlesnake bite, you're not going to end up in the news as "that guy" who abused SAR and gives a bad name to hikers.

Thanks for the ref to the Bush article saying "extractors are worse than worthless." I spent some time in PubMed and also in Google Scholar, and I found the author of the linked article is one of the main guys leading the charge against extractors. But, I can find no consensus. For example:

"Dr. Gellert makes several errors of fact and gives a controversial opinion in his letter, “Snake-Venom and Insect-Venom Extractors: An Unproved Therapy” (Oct. 29 issue)1. He is correct in stating that the application of suction to snakebites and hymenoptera stings by most devices is worthless, but he is wrong in his blanket condemnation of all such devices. Bornstein et al. have demonstrated that a patented device, the Sawyer extractor, which is capable of producing nearly 1 atmosphere of vacuum, is efficacious in removing up to 37 percent of radiolabeled venom in rabbits when applied three minutes after injection. The use of this extractor as immediate first aid has been advocated by the Wilderness Medical Society in a peer-reviewed position paper, in the Merck Manual, and in Conn's Current Therapy" — William W. Forgey, M.D. Wilderness Medical Society, Merrillville, IN 46410 Forgey WW. More on snake-venom and insect-venom extractors. N Engl J Med. 1993 Feb 18;328(7):516-7.

On the other hand, you can find other papers that extract very little radiolabeled venom with the Sawyer. The difficulty is sorting out the pros and the cons. So in a follow-up post, I'll list some of the papers I found and people can make up their own minds — difficult, since the medical establishment seems divided as well. To me, it appears most (but not all) of the current research is tilting anti-extractor, BUT, Bush is a big part of that effort and he clearly has an axe to grind. Bush seems to be at the extreme, saying the Sawyer also causes additional trauma to the bite. (There is one bizarre paper indicating, if I'm reading it right, that trauma to the bite slows the spread of venom–but don't take my word for it; pull the paper and read it before you punch yourself in your snake bite.)

EDIT to add: There's some confusion in the literature, which often combines "suction and cut" (old Cutter-style snakebite kit) and the "suction only" (Sawyer Extractor) into one category. It does appear that cutting is seldom recommended. Just be aware that some papers don't separate cutting from suction.

These are the anti-suction articles I found. I'll post the pro-suction articles next.

The Bush, SP article referenced in an earlier post above. Ann Emerg Med 2004, 43. 187-188. Snakebite Suction Devices Don’t Remove Venom: They Just Suck.

No benefit was demonstrated from Extractor use for artificial rattlesnake envenomation in our animal study. The skin necrosis noted in 2 Extractor-treated extremities suggests that an injury pattern may be associated with the device. Bush, SP et al. Effects of a negative pressure venom extraction device (Extractor) on local tissue injury after artificial rattlesnake envenomation in a porcine model. Wilderness & Environmental Medicine Volume 11, Issue 3, September 2000, Pages 180–188

Of the 48 Web sites reviewed, 26 (54.1%) contained inappropriate recommendations. …inappropriate treatment recommendations included: suction (14); ice (6); incision (4); electric shock (1). –Barker S et al. Accuracy of internet recommendations for prehospital care of venomous snake bites. Wilderness Environ Med. 2010 Dec;21(4):298-302. doi: 10.1016/j.wem.2010.08.016. Epub 2010 Aug 14.

The management of poisonous snake bites includes first aid and clinical medical treatment. First aid consists of reassurement of the patient, immobilisation of the bitten limb and rapid transport to the nearest hospital to monitor the vital functions. In no case suction, incision or tight bandages should be applied. — Carels RA1 et al. [Acute management of patients bitten by poisonous snakes]. Ned Tijdschr Geneeskd. 1998 Dec 19;142(51):2773-7.

In the United States, poisonous snakes account for approximately 8,000 bites annually, resulting in about 9 to 15 fatalities. The majority of deaths occur in children, the elderly, and untreated or mistreated individuals. Pit vipers account for almost all bites. … First aid treatment should focus on transporting the victim to the nearest medical facility as soon as possible. Previously advocated first aid measures such as tourniquet, incision and suction, cryotherapy, and electric shock should be avoided. The mainstay of treatment for envenomation is the prompt administration of sufficient quantities of the appropriate antivenin. — Gold BS1, Wingert WA. Snake venom poisoning in the United States: a review of therapeutic practice. South Med J. 1994 Jun;87(6):579-89.

The Sawyer Extractor pump removed bloody fluid from our simulated snakebite wounds but removed virtually no mock venom, which suggests that suction is unlikely to be an effective treatment for reducing the total body venom burden after a venomous snakebite. –Suction for venomous snakebite: a study of "mock venom" extraction in a human model. Alberts MB1, Shalit M, LoGalbo F. Ann Emerg Med. 2004 Feb;43(2):181-6.

[Unable to retrieve article but assume it's negative toward extractors] — Gellert GA. Snake-venom and insect-venom extractors: an unproved therapy. N Engl J Med. 1992 Oct 29;327(18):1322. [See rebuttal by Forgey, MD.]

The Venom Ex apparatus has been evaluated for the treatment of puff adder bite. Rabbits were injected with double the lethal dose of puff adder venom, followed by treatment with the Venom Ex cutting and suction apparatus. Controls received no treatment. The percentage of venom extracted as determined by radial immunodiffusion was very low after intramuscular injection and significantly higher after subcutaneous injection. However, all treated and control animals injected subcutaneously, recovered while all animals injected intramuscularly died, irrespective of treatment. Blood venom levels were extremely low in all animals. Venom Ex treatment did not improve survival or affect local necrosis significantly. — Reitz CJ, Willemse GT, Odendaal MW, Visser JJ. S Afr Med J. 1986 May 24;69(11):684-6.

[Unable to retrieve article. Assuming it is anti-extraction, maybe it’s not.] D.L. Hardy Sr A review of first aid measures for pitviper bite in North America with an appraisal of Extractor® suction and stun gun electroshock J.A. Campbell, E.D. Brodie Jr (Eds.), Biology of the Pitvipers, Selva, Tyler (1992), pp. 405–414

These are the Pro-suction (or at least neutral) citations I found.

Dr. Gellert makes several errors of fact and gives a controversial opinion in his letter, “Snake-Venom and Insect-Venom Extractors: An Unproved Therapy” (Oct. 29 issue)1. He is correct in stating that the application of suction to snakebites and hymenoptera stings by most devices is worthless, but he is wrong in his blanket condemnation of all such devices. Bornstein et al.2 have demonstrated that a patented device, the Sawyer extractor, which is capable of producing nearly 1 atmosphere of vacuum, is efficacious in removing up to 37 percent of radiolabeled venom in rabbits when applied three minutes after injection. The use of this extractor as immediate first aid has been advocated by the Wilderness Medical Society in a peer-reviewed position paper,3 in the Merck Manual,4 and in Conn's Current Therapy — William W. Forgey, M.D. Wilderness Medical Society, Merrillville, IN 46410 Forgey WW. More on snake-venom and insect-venom extractors. N Engl J Med. 1993 Feb 18;328(7):516-7.

….Rattlesnakes cause most snakebites and related fatalities.….First-aid techniques such as arterial tourniquets, application of ice, and wound incisions are ineffective and can be harmful; however, suction with a venom extractor within the first five minutes after the bite may be useful. Juckett G1, Hancox JG. Venomous snakebites in the United States: management review and update. Am Fam Physician. 2002 Apr 1;65(7):1367-74.

Most hospitalized victims are bitten either by rattlesnakes or copperheads or by unidentified snakes. Most of these bites occur during the summer months and are found on the extremities. Field treatment focuses on the application of a vacuum extractor and transportation to the nearest medical facility. Blackman JR1, Dillon S. Venomous snakebite: past, present, and future treatment options. J Am Board Fam Pract. 1992 Jul-Aug;5(4):399-405.

Proven measures to slow systemic absorption are limited but should include immobilization of the bitten extremity in a neutral position in every case, and the patient should maintain strict bed rest….A suction device, if applied and functioning, should be left in place. –McKinney PE, Out-of-hospital and interhospital management of crotaline snakebite. Ann Emerg Med 2001 Feb 37 (2) 168. Comment: Immediate removal of extractor is recommended. Bush SP, Hardy DL Sr. Ann Emerg Med. 2001 Nov; 38(5):607-8

[non-snake]…a commercially available venom extractor was demonstrated to be a safe, noninvasive, and painless method for botfly extraction in the field without use of hospital resources. Simple and effective field extraction of human botfly, Dermatobia hominis, using a venom extractor. West JK. Wilderness Environ Med. 2013 Mar;24(1):17-22. doi: 10.1016/j.wem.2012.09.007. Epub 2012 Dec 14.

Although no therapy is universally accepted, a number of treatment plans appear to be effective. If envenomation has occurred, intravenous administration of antivenin and/or surgical excision or incision should be carried out without delay. Prompt transferral to a medical facility is the most appropriate first-aid measure. If transportation is unduly delayed, immediate linear incision and suction may be of value. Johnson CA. Management of snakebite. Am Fam Physician. 1991 Jul;44(1):174-80.

Venomous snakebite treatment is controversial. …Approximately 10 to 15 individuals die from snakebites each year, with bites from diamondback rattlesnakes accounting for 95 percent of fatalities. …Approximately 25 percent of all pit viper bites are "dry" and result in no envenomation. The best first aid is a set of car keys to get the victim to a facility where antivenin is obtainable. Incision and suction should be limited to very special situations; cryotherapy and use of tourniquets applied by laymen should be avoided. Kurecki BA 3rd1, Brownlee HJ Jr. Venomous snakebites in the United States. J Fam Pract. 1987 Oct;25(4):386-92.

The Venom Ex cutting and suction apparatus for the initial treatment of snakebite was evaluated. Rabbits were injected with radioactive Egyptian cobra venom, and treatment with the Venom Ex followed. The fluid obtained by suction was analysed. All 8 control animals died within 4 hours; Venom Ex treatment resulted in the recovery of 7 out of 8 rabbits, after double the lethal dose of venom, providing treatment was started early. However, if treatment was delayed or if the dose of venom was high, there was a marked increase in the mortality. The amount of venom extracted was insufficient to account for the recovery of the animals. In one group of rabbits trauma was applied to the injection site without lacerating the skin and without removal of venom. About half of these animals recovered. However, this was less efficient than the Venom Ex treatment. Trauma apparently retards absorption of venom and increases survival. The possible reasons for this novel finding are discussed. S Afr Med J. 1984 Jul 28;66(4):135-8. Evaluation of the Venom Ex apparatus in the treatment of Egyptian cobra envenomation. A study in rabbits. Reitz CJ, Goosen DJ, Odendaal MW, Visser L, Marais TJ.

Could not find citation. This is the study that finds 37% of venom removed. –A.C. Bronstein, F.E. Russell, J.B. Sullivan, N.B. Egen, B. Rumack. Negative pressure suction in field treatment of rattlesnake bite. Vet. Hum. Toxicol., 28 (1985), p. 297
.
Could not find citation. A.C. Bronstein, F.E. Russell, J.B. Sullivan, N.B. Egen, B.H. Rumack. Negative pressure suction in the field treatment of rattlesnake bite victims. Vet. Hum. Toxicol., 28 (1986), p. 485
.
Could not find citation (letter). B.S. Gold, Snake venom extractors: a valuable first aid tool, Vet. Hum. Toxicol., 35 (1993), p. 255

Since I am — to my utter horror — somewhat of a rattlesnake magnet, and I live in Arizona, I sometimes hike with Kevlar snake gaiters (usually when I wear them, I have no snake encounters, LOL; it's when I DON'T wear them that I get buzzed at!).

Why not wear them all the time? They're hot. Really hot. Like, no air circulation from my toes to my knees. But do I feel psychologically better when I'm wearing them? Yes. And I also enjoy the added benefit of protection from nasty spiky plants like Amole (aka Shin Dagger) and Spanish Bayonet. I always wear them for bushwhacking.

One of my friends was bitten a few years ago while walking her dog in a remote suburb. She said the pain was almost immediate, and quite intense. She was able to call 9-1-1 within seconds, and an ambulance picked her up in less then 30 minutes. Although only one fang of a small rattlesnake pierced her heel, she spent four days in intensive care, and received quite a lot of anti-venom (I forget how much). The swelling was enormous, but because she got help so quickly, she had no permanent damage to her foot/leg.

Pray that you never experience a bite. I know I do. Regularly. Rattlesnakes are everywhere here. I will NEVER get over the one on the back patio under the barbeque…

Snake bites are pretty rare in the backwoods – I was active in SAR in Southern Arizona in the 70s and 80s. In something like 500 operations,how many snakebites did we deal with? NONE – zero, nada, zilch. Statistically, snakebites are a very minor hazard, compared to falling, or even drowning, in the American Southwest.

I read somewhere that the Native American remedy for snakebite was to simply find a sheltered spot, sit down, and rest until relieved (sorry, no reference). Nice and lightweight- LNT, too, for that matter…

By the way Delmar, Dr. Bush works in a hospital pretty close to you (if he's still there), likely your closest trauma center. His young son was bitten a few years ago, it was in the local newspaper. I guess if you get bit, its good that your dad is one of the foremost snakebite experts in the country.

Rattlesnake bites have the potential to be extremely serious, thankfully less than 3% of bites are fatal. But they can cause major tissue damage regardless. That being said, I don't worry much about them. I only see them occasionally, but twice in one week I stepped within 6 inches of one, once directly in front of a coiled rattler who's meal I scared off. He could have bit me easily, but didn't. I have an informal agreement with snakes….They don't bite me, and I don't kill them and take them with me to the hospital for identification. So far, they have kept up their end of the agreement, and so have I. We are too big for them to eat, they don't want to waste their venom on us.

I have an informal plan in my head as to whether or not I would walk out or try to seek other help, depending on where I am. If I am alone with little chance of rescue anytime soon, I walk out as calmly as possible regardless of distance. If I am far from help but have communications to the outside world, I would likely call for help. If I'm only a few miles out and have communication, I would call 911 and have the ambulance meet me at the trailhead. I don't carry any kind of snakebite kit and like anything else, prevention is by far the best way to go.

Slightly off topic, but I've put this info into my smartphone under "Snake ID":

Mojave: diamonds fade away to indistinct bands on last 1/3 of snake, before the b/w section. On b/w bands, the white are often wider (but not always). Pale diagonal scales behind eyes may not extend to lip, may go behind corner of mouth. Have 2-3 enlarged/prominent scales between eyes. May have a greenish tinge but not diagnostic. Neurotoxic (nervous system).

Western Diamondback: diamond pattern continues all the way to the b/w tail bands. The b/w bands are of roughly equal size (or the black may be larger). Pale diagonal scales behind eyes extend to upper lip in front of corner of mouth. Scales between eyes are uniformly small and many. Hemotoxic (attacks red blood cells).

Posted here for revision/correction/discussion

> Statistically, snakebites are a very minor hazard, compared to falling, or even drowning, in the American Southwest.

Maybe, but: If one doesn't engage in fall-prone rock climbing, or camp in slot canyons, and one DOES hike where there are lots of rattlers, then the averages are less comforting. Possibly worse than dying, is living with permanent liver or brain damage. So "death" is probably not the best dependent variable to use when considering snakebite. I'm more worried about disability.