The local lesion is a puncture, surrounded by a zone of hyperæmia, wheals, or vesicles, and is associated with burning sensations and itching which usually pass off in a few hours, but may recur at intervals, especially when the patient is warm in bed. Scratching also reproduces the local signs and symptoms. Where the connective tissue is loose—for example, in the eyelid or scrotum—there is often considerable swelling; and in the mouth and fauces this may lead to œdema of the glottis, which may prove fatal.
The treatment consists in the local application of dilute alkalies such as ammonia water, solutions of carbonate or bicarbonate of soda, or sal-volatile. Weak carbolic lotions, or lead and opium lotion, are useful in allaying the local irritation. One of the best means of neutralising the poison is to apply to the sting a drop of a mixture containing equal parts of pure carbolic acid and liquor ammoniæ.
Free stimulation is called for when severe constitutional symptoms are present.
Snake-Bites.—We are here only concerned with the injuries inflicted by the venomous varieties of snakes, the most important of which are the hooded snakes of India, the rattle-snakes of America, the horned snakes of Africa, the viper of Europe, and the adder of the United Kingdom.
While the virulence of these creatures varies widely, they are all capable of producing in a greater or less degree symptoms of acute poisoning in man and other animals. By means of two recurved fangs attached to the upper jaw, and connected by a duct with poison-secreting glands, they introduce into their prey a thick, transparent, yellowish fluid, of acid reaction, probably of the nature of an albumose, and known as the venom.
The clinical features resulting from the injection of the venom vary directly in intensity with the amount of the poison introduced, and the rapidity with which it reaches the circulating blood, being most marked when it immediately enters a large vein. The poison is innocuous when taken into the stomach.
Locally the snake inflicts a double wound, passing vertically into the subcutaneous tissue; the edges of the punctures are ecchymosed, and the adjacent vessels the seat of thrombosis. Immediately there is intense pain, and considerable swelling with congestion, which tends to spread towards the trunk. Extensive gangrene may ensue. There is no special involvement of the lymphatics.
The general symptoms may come on at once if the snake is a particularly venomous one, or not for some hours if less virulent. In the majority of viper or adder bites the constitutional disturbance is slight and transient, if it appears at all. Snake-bites in children are particularly dangerous.
The patient's condition is one of profound shock with faintness, giddiness, dimness of sight, and a feeling of great terror. The pupils dilate, the skin becomes moist with a clammy sweat, and nausea with vomiting, sometimes of blood, ensues. High fever, cramps, loss of sensation, hæmaturia, and melæna are among the other symptoms that may be present. The pulse becomes feeble and rapid, the respiratory nerve centres are profoundly depressed, and delirium followed by coma usually precedes the fatal issue, which may take place in from five to forty-eight hours. If the patient survives for two days the prognosis is favourable.
Treatment.—A broad ligature should be tied tightly round the limb above the seat of infection, to prevent the poison passing into the general circulation, and bleeding from the wound should be encouraged. The application of an elastic bandage from above downward to empty the blood out of the infected portion of the limb has been recommended. The whole of the bite should at once be excised, and crystals of permanganate of potash rubbed into the wound until it is black, or peroxide of hydrogen applied with the object of destroying the poison by oxidation.