March 1995; rev. 2008
However terrifying a venomous snakebite may be, experts say that with prompt medical attention the chances of surviving the incident are better than you might expect.
For much of recorded human history, the treatment for snakebite was more unpleasant--and sometimes more dangerous--than the bite itself. Ancient Egyptians cut open a snakebitten limb to let the evil spirits out. Ancient Romans amputated the bitten body part. In 1648, physician Guilherme Piso wrote that "the severed head of the very serpent causing the bite should be applied to the wound in the form of a plaster." American cowboys in the 19th century treated snakebite with a hot branding iron, while others of that era wrapped the bitten limb in a split chicken.
While treatments today aren't this extreme, there remains considerable controversy over first aid for snakebite. Should you use a tourniquet? How about an ice pack? Cut and suck? Apply electrical current? Even among modern-day physicians there have been differences of opinion on medical treatment of snakebite, with almost every recommendation being the subject of controversy at some time.
For all the attention given venomous snakebite, it is not a major health problem in the United States. Most people are never more than an hour or so away from a hospital, and antivenin treatments are widely available and effective. In fact, experts say that more damage can be done by improperly administered first aid than by the bite itself. Deaths from venomous snakebite never have been high in Texas, and the Texas Department of Health's Bureau of Vital Statistics recorded no snakebite deaths in 1991, 1992 and 1993. The bureau recorded just three snakebite deaths in 1989 and 1990 combined.
It's far more likely that any snake you encounter in Texas will not be one of the venomous species. Most snakes are harmless; all are essential parts of our ecosystem. For example, many snakes help keep populations of prolific mice in check. Only 15 of the approximately 113 species and subspecies of snakes found in Texas are venomous, and some of these are in remote areas where contact with humans is rare.
There are four groups of dangerously venomous snakes in North America, and Texas has all four: rattlesnakes, copperheads and cottonmouths, which are known as pit vipers; and coral snakes. Pit vipers are named for the heat-sensitive pits on either side of the face, which the snake uses to locate warm-blooded prey. These snakes have long, movable fangs at the front of the upper jaw, which stay folded back against the roof of the mouth until the snake is ready to strike. As the pit viper opens its mouth the fangs swing forward to a 90-degree angle. The snake then strikes with a stabbing motion of its head and injects venom through the fangs.
The coral snake is the only dangerously venomous snake in the U.S. that is not a pit viper. Its fangs are short, small and do not move. The coral snake's mouth is small and bites are rare, but very toxic. Bites from the generally non-agressive coral snake are most often from someone touching or handling this snake.
Snake venoms are complex mixtures. Pit viper venoms contain several destructive substances, and while symptoms vary according to the species of snake, they usually include immediate and intense pain, followed by swelling and discoloration. If not treated within an hour, the victim may have a tingling sensation in the face and a metallic taste in the mouth. Nausea, vomiting, chills, blurred vision and thirst may follow, with a drop in blood pressure causing faintness.
Unlike pit viper venom, coral snake venom is primarily a neurotoxin. There is little or no pain and swelling, and symptoms may not appear for hours. But once symptoms do appear, they progress rapidly: euphoria and drowsiness, nausea and vomiting, headache, difficulty in breathing and paralysis. As noted earlier, coral snakes bites from this species are rare.
Prior to the 1950s, most snakebite incidents were associated with agricultural activities such as picking berries, clearing weeds or other farm chores. Nowadays, most bite victims are people who deliberately come in contact with snakes: hunting them, catching them, studying them and similar activities. Otherwise, snakebites usually occur when the snake is stepped on, or when an unsuspecting person lifts a log or rock under which the snake was hiding. Young children attracted by the coral snake's bright colors have been bitten when they picked up the pretty serpent. Overall, children have the highest incidence of snakebite, people over 70 the lowest. In the South, 95 percent of all snakebites occur between the months of April and October.
First aid procedures that have gained favor over the years all have had the same goal: to remove the venom, or at least localize it in the area that was bitten and keep it from spreading throughout the body. Cryotherapy, the therapeutic use of cold, is one folk cure that survived well into the 20th century. The theory was that cooling the bitten area with ice or a chemical refrigerant would inactivate the enzymes in the venom and slow its absorption. Newspaper and magazine articles in the 1950s and 1960s carried headlines such as "Freeze Away the Horrors of Snakebite" and "Snake Bite--Cool It." But enthusiasm for the technique cooled as doctors reported serious complications. Ice packs left too long on the affected limb caused frostbite, which in severe cases required amputation. Also, some researchers reported that the venom became as active as ever when the ice was removed and the limb rewarmed. Dr. Findlay E. Russell of the University of Arizona objects to the use of ice on a snakebite "because we see no value for local ice except to reduce pain, and I don't feel this is a wise thing to do before diagnosis."
Use of a tourniquet or ligature to restrict the spread and absorption of venom is another technique that has been practiced for centuries. Even as recently as 1978, the American Red Cross's guidelines for snakebite first aid stated: "If mild to moderate symptoms develop, apply a constricting band from two to four inches above the bite but NOT around a joint and NOT around the head, neck, or trunk." When prolonged use of a tourniquet was discovered to cause blood vessel damage and gangrene, first aid manuals recommended releasing the band for one minute every 10 minutes. But some experts later contended that releasing and retightening the tourniquet actually pumped the venom into the body. "Ligatures increase pain and have little effect in retarding spread of venom," said Dr. Sherman A. Minton of the Indiana University School of Medicine.
By the 1850s, incision and suction had become the most widely used treatment for snakebite in the United States. The technique consisted of making cuts over the bite and sucking out the venom. Americans have purchased thousands of snakebite kits containing a razor blade and rubber suction cups. Again, the American Red Cross's 1978 guidelines for snakebite first aid: "If severe symptoms develop, incision and suction should be performed immediately. Apply a constricting band, if not already done, and make a cut in the skin with a sharp sterilized blade through the fang mark(s).Suction should be applied with a suction cup for 30 minutes. If a suction cup is not available, use the mouth. There is little risk to the rescuer who uses his mouth, but it is recommended that the venom not be swallowed and that the mouth be rinsed."
Like cooling and tourniquets, incision and suction may be valid in theory but can be deadly in practice. Unless the blade is sterile, infection can develop. Cut a little too deeply and the victim can end up with damage to the nerves, tendons and blood vessels; he also can bleed to death. "Incision and suction, as generally taught, have no place as a first aid measure, especially if administered by an inexperienced companion," said Dr. Joseph M. Abell, Jr. of Austin. "Cruciate (cross-shaped) incisions violate good surgical principles, and mouth suction violates the most basic medical judgment."
Incision and suction can actually increase the spread of venom. "Think of it this way," said Dr. Andrew Price of the Texas Parks and Wildlife Department's Resource Protection Division. "If a person is bitten by a pit viper and venom is injected, one of two possibilities exists. The bite may have hit a major arterial or venous blood vessel, in which case the venom already is being transported throughout the body. Or the venom is sitting in a tissue pocket, moving slowly through interstitial space: the tissue damage is localized and treatment can be localized. Cut into this pocket, and you run the risk of hitting a blood vessel and helping the venom spread faster."
A technique that has received publicity in recent years is the use of high-voltage, low-amperage electrical current applied to the bite. Despite enthusiasm for the technique from many people, it is virtually impossible to find support among physicians. "So far, all of the experimental work that's been done on animals indicates that it does no good," said Minton. "At least one of the medical missionaries who first advocated this based on their experience with it in South America still maintains that it is helpful. But if so, I don't know how it would work, and a lot of people could get in big trouble with it."
"No one has ever shown it to be effective," said Dr. L.H.S. Van Mierop of the University of Florida College of Medicine about electrical current for treating snakebites. "I do not recommend it."
Most experts today believe that the less first aid done before going to the hospital, the better off the patient will be. "The most useful snakebite first aid kit consists of car keys and some coins for a call to a hospital," said Minton. He stressed that calling ahead is important, to give doctors time to prepare for the patient and consult other experts, if necessary.
"If you don't do anything, you haven't done anything wrong," said Russell.
If the snakebite victim is less than an hour away from a hospital, most authorities agree on the following steps: 1.) Reassure the victim ; keep him warm, quiet and comfortable. 2.) Remove rings and other constricting items. 3.) Loosely immobilize the injured part in a functional position and attempt to keep this part of the body just below heart level. 4.) Transport the victim to a medical facility quickly.
"Treat the victim for shock," added Price. "Anaphylactic (physiological) shock can kill as effectively as the venom itself, if not more so."
If feasible, try to identify the snake, but do not put another member of the party in danger. Remember, most snakebites occur when a person is trying to catch or kill a snake. Anyone who spends much time outdoors should become familiar with the characteristics of Texas's venomous snakes, which will facilitate identification in the field. At the hospital, the victim or his companions should be prepared to tell medical personnel where, when and under what conditions the bite occurred; the sequence of events and the onset and progress of symptoms; and all events from the time of the bite until the victim reaches the hospital.
If the victim is more than an hour away from a hospital, which could be the case in some of the remote areas of Texas, the same rules apply and rescuers should waste no time in reaching a hospital. "However," said Minton, "some type of first aid is desirable for someone bitten by a venomous snake in a situation where medical help will be delayed for an hour or more." Some experts have endorsed the use of a small, hand-held vacuum device known as a "Sawyer Extractor." Capable of producing a negative pressure of one atmosphere, the Sawyer Extractor is applied over the fang marks immediately and left in place for 30 minutes. The big advantage over traditional cut and suck first aid is that no cutting is required. According to Minton, "There's a certain amount of evidence that you get some venom out if you use it correctly."
Another technique, more useful with coral snake bites than with pit vipers, involves wrapping a wide elastic bandage around as much of the bitten limb as possible, then immobilizing it with a splint. "This works quite well against snakes such as cobras or coral snakes where you have a highly lethal venom, but one that doesn't do too much damage locally," said Minton. "With a rattlesnake, where you can have a lot of local damage, it's kind of a trade-off. If it potentially were a very bad bite and it would be a long time before you got help, you might consider using the wrapping technique with the realization that you may make things worse for that limb, but you may be saving the victim's life."
Most hospitals in the United States treat venomous snakebite with antivenin administered intravenously. Antivenin should be started within six hours after the bite, and is most beneficial in the first hour. Antibiotics and antitetanus drugs also may be given. Although controversial, a few doctors still advocate surgical removal of the bitten area.
Thanks to modern medical care, deaths from venomous snakebite are becoming a thing of the past. If you find yourself on the receiving end of a venomous snake's fangs, seek treatment immediately; failure to do so can result in amputation of the bitten limb and other permanent disabilities.
Make every effort to avoid venomous snakes. If you are unfamiliar with snakes, the best way to avoid venomous snakes is to avoid all snakes. Be careful around piles of rocks and wood piles. A 13-year-old Travis County girl learned this the hard way last year, when she and a friend were jumping on a pile of scrap wood near a shed. A rattlesnake bit her just below the ankle, and she had to undergo surgery, skin grafts and physical therapy. Likewise, don't stick your hands or feet into places you can't see, such as holes, crevices or deserted buildings. When you're out hiking or hunting, wear boots or high-topped shoes, long pants and long-sleeved shirts. Be careful sitting on or stepping over logs. Use a walking stick to prod uncleared ground, and constantly be on the lookout for snakes. And forget about the widespread belief that a rattlesnake always sounds its rattle before striking. That's not always the case. Finally, don't handle a dead venomous snake; the reflex action of the fangs can inflict a wound for up to 45 minutes after it is killed.
Snakes play an invaluable role in keeping rodent populations in check. And human beings are never prey for venomous snakes. Given the choice, the snake wants to avoid you just as much as you want to avoid it. Make sure it has every opportunity to do so.
The Venomous Snakes of Texas
Anyone who spends much time outdoors should learn to identify Texas's venomous snakes. In the event of a snakebite, doctors treating the victim will need to know the species of snake involved, since lab tests and treatment will vary according to the species.
Pit vipers (rattlesnakes, copperheads and cottonmouths) have an opening on each side of the head between the eye and the nostril. They also can be identified by their elliptical eye pupils and triangular heads.
Copperheads have chestnut or reddish-brown crossbands on a lighter colored body. These snakes are found in rocky areas and wooded bottomlands and are rare in dry areas. In the spring they can be found along streams and rivers, as well as in weed-covered vacant lots. There are three subspecies of copperheads in Texas: the southern copperhead, 20 to 30 inches long and found in the eastern one-third of the state; the broad-banded copperhead, about two feet long, widely scattered in central and western Texas; and the Trans-Pecos copperhead, 20 to 30 inches in length and found near springs in the southern part of the Trans-Pecos.
Cottonmouths can be dark brown, olive-brown, olive-green or almost solid black. They are marked with wide, dark bands, which are more distinct in some individuals than in others. Juvenile snakes are more brilliantly marked. The cottonmouth gets its name from the white tissue inside its mouth, which it displays when threatened. The western cottonmouth is the only subspecies in Texas. This heavy-bodied snake, which averages about 3-1/2 feet in length, is found over the eastern half of the state in swamps and sluggish waterways, coastal marshes, rivers, ponds and streams. Following flooding in southeast Texas last fall, a Houston man was surprised when a cottonmouth fell on his feet from under the dashboard of his truck.
Rattlesnakes comprise about half the venomous snakes in Texas. The 10 species and subspecies vary in size from the 18-inch western pigmy rattler to the western diamondback, which can reach seven feet in length. All have triangular-shaped heads, elliptical pupils and rattles, which are interlocking horny segments that vibrate against each other. The rattlesnake species that pose the greatest threat to humans in Texas are the western diamondback, prairie rattler and Mojave rattler. For the most part, the other species are uncommon or occur in regions where they have little contact with humans.
Western massasauga: Light gray, with brown oval blotches along the middle of the back and smaller blotches along each side. Two feet in length. Found through the middle of the state in grasslands, marshy and swampy areas.
Desert massasauga: Lighter in color than the western massasauga, smaller and more slender. Found in the Trans-Peocs, western Panhandle and the lower Rio Grande Valley.
Western pigmy: Gray to grayish brown with small, dark spots along the back and smaller dots along each side. Grows to about 18 inches in length and found in the eastern part of the state.
Western diamondback: Brown, diamond-shaped markings along the middle of the back and alternating black and white rings on the tail. Averages 3-1/2 to 4-1/2 feet in length, and can reach seven feet. This is the most common and widespread venomous snake in Texas, found in all but the easternmost part of the state.
Mojave: Similar to the western diamondback in markings, but smaller and more slender and found only in extreme West Texas.
Canebrake: Large, heavy-bodied snake averaging 4-1/2 feet. Brown or tan with wide, dark crossbands. Tail is entirely black. Found in the eastern third of the state in wooded areas in wet bottomlands.
Mottled rock: Light cream or pink background with widely spaced, dark crossbands and mottled areas between the crossbands. Small and slender with an average length of about two feet. Found in the mountainous areas of West Texas.
Banded rock: Similar to the mottled rock rattlesnake, but darker greenish-gray in color. Found only in the extreme western tip of Texas.
Black-tailed: Gray to olive green with dark blotches along the back and a black tail. Average length of 3-1/2 feet. Found from Central Texas throughout most of West Texas in bushes and on rocky ledges.
Prairie: This slender rattler is greenish or grayish with darker, rounded blotches down the middle of its back. Average length is about three feet. Found in the grassy plains of the western third of the state.
The brightly colored Texas coral snake is the state's only member of the Elapidae family, which includes the cobras of Asia and Africa. The coral snake is slender with a small, indistinct head and round pupils, and usually is 2-1/2 feet or shorter. Its distinctive pattern is a broad black ring, a narrow yellow ring and a broad red ring, with the red rings always bordered by the yellow rings. Several harmless snakes are similarly marked, but never with the red and yellow touching. "Red on yellow, kill a fellow; red on black, venom lack," is a handy way to distinguish the highly venomous coral snake from nonvenomous ringed species. Coral snakes are found in the southeastern half of Texas in woodlands, canyons and coastal plains.
Snake Venom Study Underway at Chaparral WMA
Is the venom produced by South Texas rattlesnakes different from that of rattlers in other parts of the country? Could snake venom lead to a cure for human diseases? These are some of the questions that may be answered by a study in progress at the Texas Parks and Wildlife Department's Chaparral Wildlife Management Area.
Rattlesnakes from the 15,000-acre wildlife management area are being milked for their venom, which then is being studied by Dr. John C. Perez of Texas A&I University in Kingsville. Perez is trying to determine whether there is any genetic variation between the Chaparral snakes and snakes from other regions. This could lead to the development of an antivenin more specific to bites from those snakes.
Other research concerns animals that are virtually immune to rattlesnake venom, such as the Mexican ground squirrel, opossum and wood rat. These species have factors that inhibit the venom from causing hemorrhaging of tissue, and Perez thinks this anti-hemorrhage ability merits further study. Also of possible benefit to humans is a study of whether venom could be used to destroy tissue that needs to be destroyed, such as tumors.
Snakes captures at the Chaparral WMA for the study eventually are released with a tiny transponder under the skin that will allow biologists to recapture them and record information about growth rates and habitat use.