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Tue Jul 1 04:33:03 BST 2008

Ken
As you are aware, most poisonous snakes produce their venom in an analog
of the parotid gland. As such the venom for all is made up of the same
constituents. These digestive enzymes which start to digest the pray
from the inside when they are bitten. These venoms contain both
hematogenous and nerve agents. The % of nerve vs hematogenous varies
from species to species. The pit vipers (our most common venomous snake
in the US) is mostly hematogenous hence the swelling and discoloration.
The snakes which have mostly nerve venom such as the coral snake in the
US and even more the Cobra and its relatives even the so called spitting
snake used to blind his prey. The venom is actually sprayed from a
special fang with holes in the front rather than the tip.

I agree with you that most envenomations in the US are from the pit
vipers and do not necessarily need the antivenom and its associated
problems. Although the newer forms of the antivenom are not made from
horses and do not have the serum sickness associated with their use.
The physician can judge amount of envenomation and strength of the venom
based on swelling and discoloration. This is a result of the type of
venom (hematogenous destruction). Since the snakes without a predominate
amount hematogenous venom do not produce swelling and the first
indication of problems is the neurologic changes.

Finlay Russell, MD, PhD in Arizona has been, to many of us, for the last
50 years or so, the guru for venomous snakes and other animals (spiders
included). I will be happy to share with you (offline) his contacts if
you wish

Norman

Norman McSwain Jr, MD FACS
Trauma Director Charity Hospital
Professor of Surgery
Tulane University School of Medicine
504 988 5111

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