How to Recognize Snake Venom Poisoning 



or more of the. organ systems of the body. 



It is also apparent tliat quantitative and, per- 

 haps, qualitative differences in the chemistry of 

 venoms may occur at the species level and may, in 

 fact, be evident in snakes of the same species 

 taken from different geographic areas. Thus, 

 dillVi-ences in the symptoms and signs of poison- 

 ing may occur even when similar snakes are in- 

 volved in a series of accidents. 



In Table 1 are given the names of some of the 

 more important venomous snakes of the world, 

 their aclult average lengths, llic approxiiiiafe 

 amount of dried venom contained within their 

 venom glands (adult specimens), and the intra- 

 peritoneal and intravenous LD50 in mice, as ex- 

 pressed in milligrams of venom (on a diy weight 

 basis) per kilogram of test animal body weight. 

 The purpose of this table is to demonstrate the 

 consideraljle differences that exist in the lethality 

 of various snake venoms. 



In general, the venoms of the vipers cause 

 deleterious changes in the tissues both at the site 

 of the bite and in its proximily, changes in (lu- 

 red blood cells, defects in coagulation, injury to 

 the blood vessels; and, to a lesser extent, damage 

 to the heart muscle, kidneys, and lungs. The 

 venom of the tropical rattlesnake, Crotahis dvris- 

 siis. causes more severe changes in nerve conduc- 

 tion and neuromuscular transmission than do 

 other crotalid venoms. The venoms of the ela))id 

 snakes cause lessei- local tiss\u> changes, but often 

 cause serious alterations in sensory and motoi- 

 function as well as cardiac and resi)iratory dilli- 

 culties. 



SYMPTOMS AND SIGNS 



The symptoms, signs, and the gravity of snake 

 \enom poisoning are dependent upon a number of 

 factors: the age and size of the victim, the na- 

 ture, location, depth, and numbei- of bites, the 

 h'ligtli of time the snake holds on, the extent of 

 anger or fear that motivates the snake to sti'ike, 

 the amount of venom injected, the s])ecies and 

 size of the snake involved, the condition of its 

 fangs and venom glands, the victim's sensitivity 

 to the venom, the pathogens present in the snake's 

 mouth, and the degree and l<ind of tii'st aid 

 and subse(iuent medical care. It can lie seen that 



snakebites may vary in severity fioni trivial to 

 extremely grave. 



The findings given in tables 2, ?>, and 4 are 

 those observed in what may l>e termed typical, 

 moderately severe cases of snake venom poison- 

 ing. AVliile they are not complete, tliev do pro- 

 \ide a ready inference of the more commonly 

 oliserved se(|uelae of liifes by venomous snakes. 



Diagnosis of crotalid envenomation is depen- 

 dent upon the jiresence of one or more fang 

 marks, and immediate and usually progressive 

 swelling, edema, and pain. In most cases swell- 

 ing and edema are constant findings and are 

 usually seen about the injured area within 10 

 minutes of the bite. In the absence of treat- 

 ment, the swelling progresses rapidly and may in- 

 volve the entii-e injured extremity within one 

 hour. Generally, however, swelling and edema 

 spread more slowly, and usually over a jieriod of 

 8 to no hours. Swelling and edema are most 

 marked following bites by the Xorth American 

 rattlesnakes (excluding the ^fojave. massasaugas, 

 and pigmy rattlesnakes) and the .Vmerican lance- 

 lieaded vipers {Bothropn). Swelling is slightly 

 less marked following i)i(es by the Malayan pit 

 viper {Agkl^f radon rhndofifoinn) and related 

 species, the Asian lance-headed vipers (Trhnrres- 

 unis), and the .Vmerican moccasins (Af/kisfro- 

 (Jon). It is least acute following bites by the 

 cascabel {Crotahin diirJs-'oi.i ferrifcux). 



In many cases, discolnrat ion of the skin and 

 eccliymosis a])pear in the area of the bite within 

 several hours. The skin apjiears tense and shiny. 

 Vesicles may form within " hours, and are gen- 

 erally present by the end of '24 hours. Hemor- 

 rhagic vesiculations and ])etechiae are connnon. 



Pain inunediately following the bite is a com- 

 mon conqilaint in most cases of crotalid poison- 

 ing. It is most se\ere following bites by the 

 SoiUli .American pit vipers (except for the cas- 

 cabel. which is less severe) : the eastern diamond- 

 l)ack. western diamondback. and timber rattle- 

 snakes of Xorth America, and the .\sian lance- 

 ])eaded vi])ers. 



Weakne-ss, sweating, faintness, and nausea are 

 commonly reported. Regional lymph nodes may 

 be enlarged, ])ainful. and tender. A very com- 

 mon complaint following bites by some rattle- 

 snakes, and one sometimes reported following 

 other pit viper bites, is tingling or numbness over 



