ANAESTHESIA. 45 



the spraying of certain liquids, like ether, ethyl chloride, or anestile, or 

 b}' the subcutaneous injection of cocaine, eucaine, or stenocarpine 

 solutions. 



Anaesthetics have a less extended usefulness in animals than in 

 man. Pain should be spared as far as possible, but expense must 

 always be considered, and anaesthesia has its drawbacks. For most 

 minor operations, the means of control at our disposal are sufficient 

 without general anaesthetics, but certain operations cannot be performed 

 without them. In reduction of hernia, delivery in cases of dystokia, 

 laparotomy, and in all cases where one works in dangerous proximit}' 

 to important organs, the animal's struggles render anaesthesia almost 

 indispensable. It is also necessary for delicate operations on or in the 

 vicinity of the eye, and for all serious operations on valuable horses, 

 whose struggles are particularly violent. Moller recommends anaesthesia 

 in castrating horses with ver}- powerful dorsal muscles. In ruminants 

 anaesthesia is seldom resorted to save in difficult parturition. In carnivora, 

 and especially in the dog, its principal indications are in laparotomy, 

 difficult parturition, amputations, and certain operations on the head. 



Anaesthesia is contra-indicated (i) in diseases of the heart (lesions 

 of the valves or myocardium, dilatation, and hypertrophy) ; (2) diseases 

 of the respiratory tract (emph3'sema, pneumonia, and chronic pleurisy). 



Ether is the best anaesthetic for subjects with emphysema and dila- 

 tation of the right heart, chloroform for those with affections of the left 

 heart, chloral when the pulse is intermittent (Arloing). 



Death may be caused by pushing administration too rapidly ; 

 in certain rare cases it may also result from accidents like vomiting, 

 the vomited material passing into the trachea and lungs, and 

 producing mechanical pneumonia. Such a termination is much to 

 be feared in man unless the patient be properly prepared, but it 

 very seldom occurs in the horse. If in operations on the face, such as 

 trepanation of the facial sinuses or nasal cavities, or extraction of 

 molar teeth, an anaesthetic be employed, the head should be placed in 

 a depending position, so as to favour escape of blood, which might 

 otherwise enter the respiratory tract and produce suffocation. 



(a) General Anesthesia. 



Narcosis being the result of a special action exerted directly on 

 nerve-centres by the anaesthetic agent, the first necessit}' is to insure a 

 sufficient quantity of the anaesthetic arriving at those centres. While 

 fixed anaesthetics can be administered by various channels, such as the 

 \eins, mucous and serous surfaces, the subcutaneous tissue, etc., vola- 



