Q: My story takes place in the Old West. What kind of snake might bite my cowboy and what was the treatment? Could he be in a coma for a while yet recover? Or should I think of something like a beaver?
A: There are approximately 120 species of snakes in the US, but only about 20 are poisonous. Every state has at least one venomous snake except Maine, Alaska, and Hawaii. All the bad guys are pit vipers except for the coral snake, which ranges throughout the Southeastern US. Pit vipers derive their name form the small heat-sensing “pit” near the eyes, which helps them locate prey. The deadliest of the pit vipers are the Diamondback rattlers, both Eastern and Western.
In the Old West, your character would most likely encounter a Western Diamondback or a Sidewinder, another species of rattler. Both can be deadly.
Today, with modern treatments (such as antivenin) and with more rapid transport of victims to the hospital, only 5 or 6 deaths occur out of the 7000 to 8000 snakes bites per year. In the Old West, the mortality was considerably higher. Ninety-eight percent of bites are to the extremities—legs, arms, and hands.
The signs and symptoms of snakebite are divided into local and systemic (total body) reactions. Snake venom is a complex fluid. It typically has several proteases (enzymes that breakdown proteins), which can lead to severe local tissue damage, as well as systemic neurological and blood toxins that cause the systemic symptoms.
Local effects might be fang marks, pain, swelling, redness, the appearance of bullae (blisters), lymphangitis (red streaks up the extremity), and painful knots in the arm pit or groin (due to swelling of the lymph nodes). The localized damage can be so severe that surgical debridement (removal of dead tissue) and even amputation might be necessary. Also, infection can occur in the injured tissues, which can also be serious and deadly, particularly true in the pre-antibiotic era of the nineteenth century.
Systemic symptoms include nausea, vomiting, numbness and tingling if the hands, face, and feet, weakness, a metallic taste in the mouth, shortness of breath, confusion, low blood pressure and finally shock, coma, and death. The victim’s blood might clot or hemolyze (breakdown) and either of these can lead to kidney damage and death.
Or the victim could survive. It might take several days for him to be up and around and a week or so before he regained all his strength. Survival was more likely when the envenomation was less, the victim was otherwise healthy, and he had a lucky star smiling on him.
Since you want your character to survive, I would suggest he suffer a bite to the leg or arm by a rattlesnake. A Western Diamondback if in a wooded or scrub-brush area and a Sidewinder if in the desert. He would develop the above systems, both local and systemic, and could be in a coma for a day or two, followed by a day or two of confusion and delirium. He would gradually “come around” but would be weak for several days.
There was little treatment available during the time period of your story. They would likely make a cross-cut of the puncture site and suck out the venom. Though this does little good it was a standard treatment until 30 years or so ago. They would probably put warm compresses on the bite area and watch over the victim with expectation and prayer.
A beaver would do none of this but would likely hurt like hell. Stick with the snake.