344 EFFECTS OF SNAKE VENOMS ON DOMESTIC ANIMALS. 



effect or another may be emphasised or marked according to the 

 amount injected, and the rapidity with which it is absorbed. 



Owing to the difficulty of obtaining information regarding 

 the species of the snake which has bitten, under what may be 

 termed " natural conditions," one has to resort to animal ex- 

 perimentation in order to form an idea of the symptoms pro- 

 duced Ijy the various species. For this purpose I propose to 

 detail the results produced on animals as a result of the bite 

 of known species. 



(i) Cohihrinc Venotn. — The typical venom of this class is 

 that of the Naja tripiidiaiis, and the eff'ects produced by this 

 venom are as follows : — Salivation, slowing and subsequent cessa- 

 tion of the respirations, whicli cease some considerable time 

 before the heart stops. In smaller doses the paralysis becomes 

 more marked, and as death does not rapidly ensue, the following 

 additional symptoms become apparent. Local inflammation at 

 the site of the l)ite, lachrymation, salivation, mucous discharge 

 from the mouth and nostrils, which are occasionally blood-tinged, 

 but there are no marked hremorrhagcs from the mucous surfaces. 

 There is obvious pain at the site of the bite, and engorgement of 

 the vessels causing swelling, due to eff'usion into the tissues. 

 In cases of recovery, the local lesion may suppurate an.d slough 

 away. The most evident paralysis is iliat shown in the tongue, 

 larynx and pharynx, causing salivation, inability to feed or 

 swallow, due to the action of the venom on the medulla. 



On post-inurtcni examination it will l)e seen that there is a 

 considerable haemolysis, and tlie coagulal>ility of the blood is 

 reduced. The tissues are blood-stained, and the urine blood 

 tinged if the animal has survived for some time after the ])ite. 

 Rigor mortis is well marked. There is congestion of the lungs 

 and bronchial nuicous membrane. The right heart is distended 

 with blood, the liver dark and congested. The kidneys are con- 

 gested, pulmonary (edema is common and is associated with 

 congestion in some cases f)f the ])ulmonary tissue and bronchia! 

 mucous membrane. Intestinal lia-morrhages may be present. 

 but are not common or extensive. 



The ])redominant actions of Colubrine venom are therefore 

 seen to be as follows: — General paralysis and sj^cial ])aralysis of 

 the breathing mechanism, due to neurotoxin, and the more or 

 less delayed onset of symptoms. 



Observations on the effect of the bite of a few Colubrine 

 snakes, including N. haja, N. flava, and Scpcdou hceinacJialcs. on 

 animals were noted at Onderstepoort by Andrews, and the fol- 

 lowing is a resit uic of the results obtained. 



The clinical symptoms recorded were divided into groups. 

 A local swelling was sometimes present, which was either 

 soft, insensitive and pendulous, or tense, hard and very sensitive 

 to the touch. Out of seven animals bitten by A', haja, four died 

 without showing any local swelling, but this was noted in the 

 animals which recovered. Four animals bitten by iV. flava. all 

 died. A mule which died five hours after the bite developed a 



