Our Herp Class: Lets drug snakes to help them drug us...

Tuesday, April 24, 2012

Lets drug snakes to help them drug us...

Green Racer- Example of a Colubrid rear-fanged snake.

Article Summary: How do we take out the venom from these creatures???

Prior methods of collecting venom from snakes have caused several debilitating effects in the organisms. This study sought out to explore the efficacy of a new technique of collecting venom from colubrid snakes. The toxicology and composition of the venom of rear-fanged snakes is less observed due to the the difficulty involved in the venom collection. This difficulty is due to a) the position of the venomous fangs and glands, and b) the small amount of venom naturally created by the Duvernoy's gland. This study aimed to maximize the yield of venom from the Duvernoy's gland of colubrid snakes via usage of ketamine and pilocarpine. Prior studies had been to determine the efficacy of this method, but the high dosage administered had caused many negative side effects in the snake populations. Prior methods were inconvenient because it was quite difficult to isolate saliva from venom or because yields were very low; additionally, they caused a lot violent aggression in the animals and thus, posed a greater difficulty in handling the animals and greater chance of being hurt.

Researchers were consequently searching for a method that would yield (relatively) large amounts of venom from the colubrid snakes, as well as possess a higher protein content (as this is indicative of saliva-free venom).

This study employed ketamine anesthesia followed by a parasympathetic stimulation of the Duvernoy's gland via pilocarpine. The previous experiment done with the same substances was conducted by Rosenburg et a. in 1992. In that study, the scientists used 60 micrograms ketamine /gram body weight to anesthetize the snakes, and then measured protein content of the extracted venom via dying reagents. Due to the findings of the previous study, the administered dosage of ketamine was made specific to each particular species of snake being used. The size of the snake was also a determinant. The researchers made it a point to start out 15 micrograms ketamine/gram body weight and then raise the dosage appropriately with increments of 15 micrograms of ketamine till desirable anesthetic effects were seen. There were many species that entirely resisted the effect of ketamine such as H.n nascius and D. punctatus.

Additionally, the authors say that there were a wide variety of venom and saliva yields, primarily dependent on the species and the size of the species. The largest yield of secretion was attained from H. gigas. That isn't to fool you, however, the largest secretion might not have had the largest venom (protein) content. In fact the highest protein contents or most concentrated venom was found in secretions from D.p regalis and T. nigriceps. For more specific results, please see the link below. So these authors discovered that ketamine administered at lower doses does not elicit the same aggressive reactions out of the species as it had before when administered at 60 micrograms ketamine/ gram of body weight. Although it took a little bit longer to anesthetize the snakes with the reduced dosage used in this experiment (and then incorporating the time it took to work your way up to an effective dosage), the snakes recovered in a much shorter time, and adverse reactions diminished greatly. In fact, the recovery time for ALL specimens seemed to be shorter on subsequent injections due to induction effects.

The authors also demonstrated for the safety of re-injections in short time periods for the same species of snakes. They extracted a single individual up to four times at 6 week intervals with no detectable changes in activity, feeding patterns, general health or behavioral aggression. The use of ketamine anesthetic and pilocarpine to induce secretion of the Duvernoy's glands did indeed greatly increase venom volume yields for both large and small colubrids; in fact, this method yielded the most venom out of the specimen in comparison to their counterpart studies. Although venom extraction cannot be 100% saliva free, this method seemed to be the most efficient in maintaining the highest concentrations of protein substance found in the extracted secretions. Though the efficacy and safety of this new technique was demonstrated by this experiment--it is still to be noted that species of snakes such as H. gigas still remain sensitive to ketamine; additionally, it is good to consider that some species simply do not get anesthetized by even "dangerously" high (relatively speaking) dosages of ketamine; most of these species tend to be large colubrids. But, on the other hand, this method has shown a success in safely retrieving large amounts of venom from even very small colubrids such as the Tantilla nigriceps.

So in conclusion, this seems to be a safe and relatively efficient way of extracting venom from colubrid snakes. There are some species that may be sensitive to even the lowest administered doses of ketamine and there are some species that may be entirely insensitive to the highest administered doses of ketamine, but it seems to work safely for most snakes. In fact most snakes recovered fully after 6-24 hours of treatment, with the only symptom being "excessive salivation". So now, we have a new way of drugging our snakes, taking out their venom, studying that venom and hopefully isolate some of its biologically active and beneficial components, and put them to use in medicine and who knows? maybe one day, our prescriptions might read...."protein content from snake venom" lol.