Crotalidae and Viperidae snake species is more hemotoxic than other families of snakes. Hemotoxic venom affects the blood and organs, causing a breakdown or inflammation in the body. Hemotoxic venom causes a depletion of red blood cells. When there aren’t enough red blood cells, the oxygen carrying capacity of the blood would also deplete and many body organs including the brain, heart, liver and the kidneys will suffer as a result.
Offense or Defense?
Venom evolved from digestive enzymes most likely as a means to subdue prey, but is also useful as a defense mechanisim in snakes who lack other external defense mechanisms or limbs to escape. It is interesting to note that many snakes inject venom into their prey which is beyond necessary to kill it. For example the Western Rattlesnake injects venom 300 times needed to kill a mouse (http://reptilis.net/serpentes/venom.html). While the Western Rattlesnake's venom is predominantly hemotoxic, it can also has neurotoxic effects, like many venomous snakes which do not fall into one category or the other. It is interesting to note that it appears that snakes farther north have increased hemorrhagic capabilities (Adame et al, 1990).
Hemotoxic venom is considered to be slow acting compared to other types of venoms. It can take a couple of hours for the first symptoms to occur. The initial symptoms will include nausea, dizziness, and possible chest discomfort.
The hemotoxic venom from some viper species is being used in research into possible cures and new medicines for diseases. A large number of snake bites cause the victim to have a lowered blood pressure level ACE inhibitors were approved by the FDA in 1979 to treat patients with high blood pressure and also heart disease. ACE inhibitors were developed by isolating an enzyme found in the venom of the Brazilian pit viper (Vyas, et al., 2013).
Adame, R. L., J. H. Soto, D. J. Secraw, J. C. Perez, J. L. Glenn, and R. C. Straight. 1990. Regional variation of biochemical characteristics and antigeneity in Great Basin rattlesnake (Crotalus viridis lutosus) venom. Comp. Biochem. Physiol. 97B:95-101.
Vyas, V. K., Brahmbhatt, K., Bhatt, H., , & Parmar, U. (2013). Therapeutic potential of snake venom in cancer therapy: current perspectives. Asian Pacific Journal of Tropical Biomedicine, 3(2), 156-162. doi:10.1016/S2221-1691(13)60042-8
western diamondback rattlesnake. [Photograph]. In Britannica Online for Kids. Retrieved from http://kids.britannica.com/comptons/art-52810