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Other Rattlesnakes

Myth: Baby rattlesnakes are more dangerous than adults

False! In fact, they're less dangerous! Here's why....

     Baby rattlesnakes are miniatures of their parents in every way, including the size of the glands that produce and store the venom. Babies are about the size of pencils at birth (for species like western diamondbacks and Mohaves) and their venom glands are a small fraction of the size of the glands of adults. Think about it: even if a baby injects a lot of its venom, it doesn't have very much.  Folks who run the labs that produce and sell snake venom to researchers and pharmaceutical companies laugh at the idea that babies can inject more venom. These labs don't want little snakes; they want huge ones because big snakes produce a lot more venom!

Baby western rattlesnakes (Crotalus oreganus) basking at their rookery a few days after birth. Their eyes are milky blue because they are preparing to shed the outer (corneal) layer of their skin for the first time. Mom is out of sight, just a few inches behind them. At this age, they are about the size of pencils.

     The photos below are of typical venom extractions from a baby western diamondback (Crotalus atrox) weighing just over an ounce (left) and from an adult diamondback weighing 30 ounces or almost two pounds (right).   

     And here are the actual venom yields from these rattlesnakes (below), collected by allowing them to bite into a membrane stretched over a small beaker.   

     The baby diamondback deposited two small drops of venom on the underside of the plastic membrane (red circle), while the adult squirted venom into the beaker, as well as all over the the membrane. This is the typical result from snakes of these sizes: baby rattlesnakes are tiny, and so are their venom glands. Which would you rather be bitten by? 

     Why is the venom yellow, you ask? The color is due to the enzyme L-Amino Acid Oxidase (LAAO for short), which is present in almost all rattlesnake venoms. LAAO destroys amino acids (the building blocks of all proteins), which causes hemorrhage and local swelling around the snakebite.

     Extrapolating from one of the best sources (in my opinion), the average venom yield from one-meter (39-inch) rattlesnakes is about 100X the average produced by 1/3-meter (13-inch) rattlesnakes (Glenn and Straight, 1978).

     And, in a study at Loma Linda University Medical Center (CA), emergency room staff asked rattlesnake bite victims and other witnesses from 145 rattlesnake bite incidents over ten years to estimate the size of the snake. Realizing that such estimates by excited people are likely to vary wildly, snake size was lumped into three general classes: small (less than 16 inches), medium (16-30 inches), and large (over 30 inches). Then, the Snakebite Severity Scores (described in Dart, et al., 1996) from these bites were averaged for each size class of snake (Janes, Bush and Kolluru, 2010).

Bar chart adapted from figure 1 in Janes, Bush and Kolluru (2010). I have converted the snake sizes from centimeters to inches and added the red arrows. Snakebite Severity Score of "0" is a dry bite; that is, no symptoms observed. A score of "20" is a severe envenomation with the patient's life clearly at risk.

     In the bar chart above, the average snakebite severity scores for medium and large rattlesnakes were not statistically different from one another, meaning that they were close enough that the difference could easily be the result of chance. But the scores of medium and large rattlesnakes were nearly double the average severity score produced by small rattlesnakes, and that difference was statistically significant.

     Finally, a study published in the Journal of the American Medical Association (JAMA) in 2019 analyzed records of 5,915 pitviper bites with the goal of identifying factors that physicians can use in the early evaluation of a snakebite patient to judge the likelihood that severe effects will develop. (The ultimate severity of a snakebite is often not immediately obvious.) The authors came up with four factors that can be quickly established and that correlated with increased "likelihood of severe systemic envenomation" (Gerardo et al., 2019). The four factors are:

  • Delay of 6 hours or more to reach medical care

  • Patient younger than 12 years

  • Large snake size

  • Ptosis (the medical term for drooping eyelids; useful only for neurotoxic bites)

     Gerardo and his colleagues point out that absence of these indicators is not a guarantee of a mild envenomation, as severe bites can occur in adults bitten by moderate-sized rattlesnakes who reach medical help without delay. But, concerning "baby" rattlesnakes, their identification of "large snake size"​ as a likely indicator of a severe envenomation helps to bust this myth.

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