GENERAL ANASTHESIA. 27 
combustible, if its action is:quicker and more powerful, it is also 
more dangerous than ether. The latter brings on more slowly a 
sleep which is not so deep, it gives rise to a state of excitement more 
marked ; but well administered it is almost always harmless. 
In later years, other substances and other processes have been 
recommended to obtain narcosis in various domestic animals as 
subjects. A mixture of ether and chloroform, administration of 
ether by way of the rectum, of morphine, with chloral injected 
‘into the veins, rectum or peritoneum, or of chloroform with mor-. 
phine and atropine, benzine, hypnone, urethane, paraldehyde, 
bichloride of methylene or amylene, have been recommended. For 
cattle, only alcoholic liquors in large doses can be used, as other- 
wise, in cases of accident from the operation, the meat could not be 
used by the butcher. 
In general anesthesia, the patient is put into a more or less deep 
sleep. But it is not always necessary to act upon the whole physi- 
cal system ; on the contrary, one may numb only a given part of 
the body upon which the operation is to be performed. For /ocal 
anesthesia the principal agents are: cold (snow, ice, cooling mix- 
tures, or the nebulizing of some liquids), cocaine, stenocarpine, spar- 
teine. 
. The use of anesthetics is more limited in the case of animals than 
in the case of men. No doubt we ought to endeavor to spare our 
. patients pain; but, generally, our interference must be. with as little 
cost as possible ; and also narcosis has its dangers. With means of 
restraint at our command, we can perform almost all: operations 
without having recourse to the use of anesthesia. This is useful, 
however, in some cases, to diminish or prevent struggles and sud- 
den movements of the animal at the time of the operation. The 
- struggles and motions of the animal at times render impossible the 
performance of some manipulations (reduction of hernias, distocial 
labors) ; at other times they may give rise to serious accidents when 
the hand alone or holding in it a sharp instrument moves about in a 
region, delicate on account of its anatomical disposition, as in intra- 
abdominal operations. Anesthesia is also useful in delicate opera- 
tions upon the eye or its surroundings, and in all serious operations 
.upon well bred animals, whose, struggles are peculiarly violent. 
MGller recommends it for castration of horses whose backs are short 
and powerful in muscles. With ruminants anesthesia is generally 
used only in difficult labors. In carnivora, especially dogs, the 
principal uses are in laparotomy, distocial deliveries, amputations, 
and some operations on the head. 
. Among the principal cases to be noted which do not admit of the 
use of general anesthesia must be mentioned : st, Diseases of the 
heart (valvular diseases or myocarditis, dilatation, hypertrophy). 
a 
