Fangs

Now is the time to unlearn everything you’ve ever heard about snakebite.

July 1981By Comments

The first snakebite I was involved with happened years ago on the back porch of a house in South Austin, and I remember it like people recall political assassinations and earthquakes. I was asleep when I heard the screams, and not wanting to wake up, incorporated them into the fabric of my dream: Bill and Elaine, the couple downstairs, were having a terrible fight. The reality was much worse. Bill’s little Western diamondback had escaped during the night and, using the expandable-collapsible strategy that has made rattlesnakes such successful predators, fold its two-footed length into one of his tennis shoes. When he stuck in his thumb, he pulled out the rattler. By the time I got there he had shaken the snake loose and collapsed on the floor. I had just hauled him to his feet when Elaine plopped him back down, on the theory that one should move as little as possible after a snakebite. It was the only rule we could remember with certainty. Cutting Bill’s finger open was more than I could steel myself for on a moment’s notice, and while using a tourniquet seemed like a good idea, we weren’t sure where to put it. There’s not much meat on a thumb and we were dealing with a particularly skinny one, so we settled for an ice cube on the bite instead.

Bill seemed willing to accept any treatment with the same depressed equanimity: like some dying general, he had grown oblivious to everything except charging me with the responsibility of locating the vanished rattlesnake. A more immediate problem was that we couldn’t find the keys to any of the four available cars, and digging through the pile of jeans on the floor, listening simultaneously for the jangle of keys and the whir of the hidden diamondback, was such touchy going that at last we had to rely on the help of a fourth party to drive us to the hospital.

This sort of confusion is typical of the emotional chaos following the majority of venomous snakebites. Most of the panic, of course, comes from the traditional notion that the victim is going to die, but with the exception of a small child deeply bitten by a big rattler, that’s simply not the case. Even with no treatment at all, the vast majority of people bitten by Texas’ venomous snakes would not die, and with modern medical care less than one per cent do. Almost none are well-read, prepared backpackers, hunters, or campers. Those who get bitten most often are herpetologists, snake buffs like Bill, laborers working in overgrown areas around old farm buildings, and kids.

Almost all bites are inflicted by pit vipers. This group of snakes includes Texas’ ten rattlesnakes as well as its three kinds of copperheads and the cottonmouth, all of which inject their hydraulically compressed toxins well beneath the surface of the skin through curved hypodermic fangs. Crotalus atrox, the Western diamondback, is responsible for nine out of ten bites in the state. Diamondback venom is virulent and plentiful; the largest rattlers carry as much as a sixth of a teaspoon of it, although because of the spongelike internal structure of the venom glands, no pit viper can squeeze out more than a quarter of its capacity per bite. A few bites are recorded every year by East Texas canebrake rattlers and High Plains prairie rattlers, which also have a good deal of slightly less toxic venom. Getting bitten by any other species is—­at least statistically—only a theoretical danger, though feisty black-tailed rattlers are common in the Chisos, Davis, and Guadalupe mountain parklands. Pygmy rattlesnakes and massasaugas have little venom, of moderate potency, but are reclusive and seldom bite anybody except reptile collectors. By far the most virulent of the rattlers is the Mojave, a desert snake of the southwestern U.S. and northern Mexico. Its venom is exceptionally high in neurotoxins, making it ten times more potent than that of the Western diamondback. But being bitten by a Mojave in Texas is about as unlikely as being struck by lightning, since they are very rare and live only in inhospitable parts of the Trans-Pecos.

Diamondback bites are most common in Central and West Texas, while copperhead bites occur more often in wooded areas east of the Edwards Plateau, especially in new suburban neighborhoods, where the previously resident snakes encounter newly enfranchised people. Copperheads are ordinarily so docile, however, that they rarely strike unless actually stepped on or prodded. Cottonmouths are abundant along the edges of lakes, rivers, and rice fields in the eastern half of the state, but few people are bitten by them because they are fairly wary and, folklore to the contrary, almost always try—if slowly—to escape when approached. Even their notorious white-mouthed warning gape is mostly bluff—cottonmouths seldom strike from this posture unless physically molested. Though cottonmouths carry a lot of venom, they have only slightly more virulent toxins than the closely related copperheads, and are somewhat less than half as dangerous as the larger species of rattlers. (Incidentally, no one has ever been killed by tumbling off water skis into a mass of cottonmouths. I’ve heard that story about more people—always a friend of a friend—than have died from all the snakebites in the state in the last ten years.)

Texas’ only poisonous serpent that is not a pit viper is the coral snake, whose venom is even more toxic than that of the Mojave. “Red and yellow, kill a fellow” is usually too extreme a prognosis, but it’s the best way to recognize this potentially lethal reptile, which, though fairly common in most parts of Central and East Texas, is shy and seldom encountered. Because coral snakes have small teeth and lack the big injector muscles of rattlers and moccasins, they rely on chewing to introduce their venom into prey, which they grab rather deliberately; they never strike out like pit vipers and almost never bite anyone who hasn’t picked them up first. If you should be bitten by a coral snake, there is one thing that might help: since few people let the snake chew for long, much of the venom often remains in scratches on the surface of the skin, so at least part of it can be flushed away with water during the first few seconds after the bite. However, the victim still needs the quickest possible hospital care.

Wear boots and don’t stick your hands where you can’t see, and your chances of being nailed by a venomous snake approach zero. However, if you violate the statistics and get bitten—as long as it’s not by a coral snake or a Mojave—the first and foremost thing to be concerned about is permanent nerve and muscle damage from destruction of tissue around the bite. (During the Depression, when many people received no medical treatment at all, crippling rather than death accompanied the majority of even the most severe snakebites.) A small child bitten by a big rattler may still be in grave danger of death, however. In this case, binding the limb above and below the wound and quickly getting the victim to a hospital where antivenin treatment is available are appropriate emergency measures.

Otherwise, you shouldn’t spend time even trying to administer first aid. What’s almost always best for the limb is to leave it alone and get good medical treatment as soon as possible. By merely immobilizing the extremity, removing rings or shoes before swelling makes that impossible, and then getting the victim to a medical facility, you’ve done nothing wrong and a lot that’s right. Most of the right involves picking a good hospital. Smaller ones generally do little for snakebite except observe the patient and treat various symptoms as they arise. Occasionally they surgically open the entire limb to let it drain, which is called fasciotomy and which is unwise regardless of the severity of the bite. In the field, any radical first aid treatment, either tourniquets or incision and suction, is always a mistake. There’s little or no benefit to be derived, and the chance of causing substantial additional damage, including loss of the limb, is high. It also hurts like hell to slice yourself open after a snakebite, when the skin is often so sensitive, that even the touch of cloth is abrasive, and the crude cuts of the old incision-and-suction method became nearly unthinkable. Although the Red Cross still recommends incision and suction as a first aid procedure, most medical authorities concerned with snakebite treatment are adamant that little pocketknife cuts are worse than useless.

This is especially true since envenomation happens only in some cases—at the option of the snake, which, in a split second, chooses whether or not to inject its venom and, if so, how much to pump in. Fortunately, it often chooses not to give you all it’s got. Even fang punctures by the hot-tempered rattlers are free of venom about 20 per cent of the time and result in little or no toxic reaction. If the snake is feeling especially threatened and ejects a good deal of venom, there is never any question as to what’s happened. Pain-producing proteins are released from the body’ own fluids, like they are in insect bites, and, just as in an all-time whopper bee sting, burning and swelling begin to develop immediately. Even coral snake bites, which don’t swell much, are frequently characterized by alternating waves of pain and numbness. Stories of people being bitten unknowingly by rattlers and moccasins only to keel over hours later are simply untrue.

What does happen in the minutes after venomous snakebite is far less nebulous—and ordinarily extremely unpleasant. Reddening, followed by the bruiselike darkening of internal bleeding, usually characterizes the rapidly growing swelling, which may, over several hours, bloat a hand or foot to twice its normal size. This process is accompanied by an array of more generalized symptoms—usually exaggerated by galloping anxiety. The commonest are clammy skin, faintness, tremor, dry mouth, heart palpitations, and almost immediate nausea, which can sometimes cause vomiting so violent as to be dangerous in itself.

The reason for all this misery is that, internally, part of the body is being digested. The physiology of snakebite bears little resemblance to the prevailing concept in which dollops of amber toxin ooze slowly through the veins towards the heart. Instead, when a venomous snake strikes a human, within moments of the bite an inexorable metabolic disintegration of the body’s living tissue begins. An elaborate mixture of toxic proteins, venom is only partially targeted toward killing prey; its primary function is digestion, which enables the snake to eat animals plumper than itself by starting the digestive breakdown even before it swallows the prey. What this means for human victims is that even in the hospital it is almost impossible to get the poison out. For all practical purposes, venom simply becomes part of the body, and trying to extract it is generally as hopeless as trying to retrieve ink dripped on a wet sponge.

Experiments with animals have shown that even excising the entire bite area has not extracted enough venom to save the lives of individuals that received a lethal dose. Therefore, making mere drainage incisions, whether small ones through the fang marks or bigger ones that open the entire limb, is a largely futile gesture. Only rarely can even an accomplished surgeon remove a pocket of venom deposited deep within the muscle; it’s obviously nothing to try on your own.

Moreover, any self-administered incision is risky because the anticoagulant effect of pit viper venom makes it hard to stop the bleeding. Knife cuts into a bitten limb—especially incisions big and deep enough to drain the venom-saturated tissues—invariably result in a far greater loss of blood than you would expect, a loss that is particularly dangerous after sever venom poisonings because when people die of snakebite, they die of loss of circulating blood volume. Because it’s so generalized, this subtle internal bleeding often goes unnoticed. It occurs when peptides and enzymes in the venom pierce the capillary walls, allowing a fine seepage of plasma into the tissue spaces, This blood pools both in the lungs and subcutaneously in the affected limb, where it appears as swelling. Here, even a minimal amount of swelling—a two- or three- centimeter increase in the circumference of a thigh, for example—can indicate a loss into the tissue spaces of as much as a third of the body’s plasma, bringing about radical fall in blood pressure and putting the patient into potentially lethal shock.

Given the drawbacks of incision, then, what of the other traditional first aid approach—trying to localize the venom by binding or chilling? Again, except in desperate situations, most authorities feel it’s better not to try to impede the body’s essential circulatory exchange, because such attempts have so frequently had disastrous results. The worst of the containment therapies was ligature cryotherapy, or L/C, treatment, which first gained popular attention during the early fifties. Touted as a revolutionary way to avoid the perils of incision and suction, it combined instead two of the most destructive things people have ever done to their limbs: putting tourniquets around them (ligature), then chilling the constricted part in ice (cryotherapy). As might be expected, venom-saturated tissue subjected to the cell-membrane-cracking effect of massive chilling and deprived of normal blood and lymphatic flow frequently died. It died so frequently, in fact, that amputations following ligature cryotherapy became almost routine and the procedure has for the most part now been abandoned. The original assumption was that extreme cold would slow down the action of the venom, but the currently prevailing view is that nothing short of totally freezing—and thus killing—a limb can substantially deactivate reptilian poison. There is even evidence that cold may drive the venom deeper into the muscles.

Much of the emphasis on such radical first aid originated during the thirties, when doctors often didn’t see patients until two or three days after a bad bite. That’s simply not the case anymore. Because most people now reach hospitals so quickly—the longest gap between bite and treatment recorded in the state recently is five and a half hours—the horrors of long-chilled, frostbitten limbs that used to shock emergency room personnel are seldom encountered today. But a dangerous legacy of the ligature-cryotherapy school remains in the widespread use of tourniquets. Any band cinched tightly enough to cut off blood flow for more than forty minutes is likely to cause permanent injury, whether or not the damage is apparent at the time. This is such a hazardous procedure, in fact, that wrapping tight bands around a bitten limb (except in the desperate case of a toddler bitten deeply by a big rattler) is now decried by everyone involved in treating snakebite.

The ultimate means of trying to contain the venom is a surgical technique called debridement, involving the removal of the toxin-infiltrated tissues. But this operation, which usually includes stripping irreplaceable nerve sheaths and tendons, calls for such fine judgments that the majority of physicians choose instead to open the entire limb surgically in hopes that relieving the pressure by enforced drainage will make tissue removal unnecessary. They are operating, however, on the false belief that excessive swelling in the limb can cause high enough internal pressure to choke off circulation. In treating more than seven hundred snakebites, however, including many by extremely virulent exotic species, Dr. Findlay E. Russell, of the Department of Pharmacology and Toxicology at the University of Arizona, has never encountered a single case that justified this radical procedure. He has found instead that even enormous swelling is soft, involving only the shallow subcutaneous layers, and that the tissue death (except that resulting from ill-advised first aid) is the direct result of the disintegration of the body’s cells by the venom. Only a handful of experienced surgeons are capable of determining how much of the darkened tissue around the bite should be excised, and because surgical solutions have so often involved permanent impairment of the limb, the prevailing treatment for snakebite in most of the country is antivenin.

Antivenin is a crystallized assemblage of antibodies made by Wyeth Laboratories from the blood of horses injected with minimal doses of snake venom. Antivenin counters both neurological damage and local tissue death in a straightforward way: it clogs up the venom proteins until they are no longer able to attack their target cells. Like any other immunization, antivenin therapy depends on building up a sufficiently high protective level of antibodies in the bloodstream to neutralize the dispersing toxin. But because this level must be attained so quickly, the patient may experience rapid and severe allergic reactions, which can be fatal within minutes without the shock drugs and respiratory assistance of a good intensive-care facility.

Russell has met with such success in controlling these adverse reactions with antihistamines, however, that he now routinely administers antivenin, even to a patient whose preliminary skin test indicates potential hypersensitivity. Proponents of this view maintain that not only does antivenin offset the major, life-threatening systemic failures that may follow a severe snakebite but it is also the only significant method of protecting the tissue near the bite of disintegration. Nevertheless, surgery is still the primary method employed at most hospitals in Texas, although neither treatment is warranted in the majority of bites. In the last eight years Houston’s Ben Taub Hospital has administered no antivenin at all and performed only on fasciotomy, even though each year it treats an average of 25 snakebite cases.

Either treatment will almost certainly pull you through—a fraction of one per cent mortality is a good shot on anybody’s table—although pulling through is still a long way from being all right. People vary enormously in how sick they get from snakebite poisoning and how long they stay that way, but it’s generally a lot longer than you’d expect, especially with rattlesnake venom. It’s not unusual to feel absolutely rotten for weeks, even from minor poisonings where no threat to life or even limb ever existed. Long after the emergency stage has passed, muscles and organs are still having to cope with metabolic wastes left in the wake of the poisons, and violet and yellow bruiselike discolorations may show up anywhere on the body for days. Even with the best treatments, some tissue death almost always occurs in the area of the bite, and enough skin may slough off to require grafting. Because both coral snakes and pit vipers carry substantial amounts of neurotoxins, their bites can impair coordination in the limb itself for weeks, as well as affect the neck, jaw, and eyes.

In addition, the aftereffects of the treatment itself cause discomfort. Each approach has its problems. Fasciotomies left open to drain for days take a lot of healing and, like any major incision in a limb, necessarily run the risk of some permanent loss of flexibility due to scarring, though good surgical technique can keep that to a minimum. Antivenin therapy can also produce residual problems. A week to ten days afterward, as the last particles of venom precipitate out of the bloodstream, rashes, aches, and fever similar to a mild case of flu are typical, sometimes followed by heightened sensitivity to inoculation with any horse-based serum.

Being struck by a venomous snake—as bad as the worst cases are—is nevertheless one of the most interesting misfortunes, automatically conferring on the victim a degree of lifelong celebrity. Especially with the less toxic copperhead poisonings and with superficial rattler bites, the notoriety may even make getting bitten less of an ordeal. Bill’s hospital room was so full of intrigued visitors that for the first couple of days Elaine and I took turns running interference in the hallway, and when he was released, half the people we knew vied for the honor of giving him a snakebite recovery party.

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