1(14 



SCIENTIPIG AGRICULTURE 



April, 1!)21. 



Anaesthesia in General Practice' 



ALFRED SAVAGE, Macdonald CoUeg-e, Que. 



According to its literal origin, the word "anaes- 

 thesia" means a condition of insensibility. A condi- 

 tion, however, is seldom absolute and must accordingly 

 be expressed with regard to some other, or qualified by 

 a word denoting its cause, origin, extent or purpose. 

 Thus we speak of anaesthesia as local, spinal or gen- 

 eral, as partial or complete, as that produced by cocaine 

 or (chloroform, or as being for a surgical or diagnostic 

 purpose. 



Pathological insensibility does not concern us under 

 this title, so I shall confine my remarks to anaesthesia 

 deliberately produced for some purpose, such as the 

 control of pain. 



Normal stimuli are transmitted through their various 

 channels to the sensorium and there appreciated merely 

 as sensation. Abnormal ones because of their nature 

 or intensity ai-e likewise transmitted but are appre- 

 ciated as pain. 



Now, contrary to popular belief, pain is not neces- 

 sarily a bad thing. Like inflammation, wliile it is patho- 

 logical, yet it is natural. It is a danger signal but not 

 necessarily a danger in itself. It is a splendid protect- 

 ant, an excellent safeguard against overuse of the part 

 from which it emanates. t>ut like some other natural 

 l)henomena it often overdoes its purpose, producing 

 needless, if not harmful, reflexes where medical cases 

 are concerned, and annoying, though perhaps futile 

 struggles in surgical work. Its control is, tlierefore, 

 often desirable — aside altogether from the fact that the 

 [latient does not enjoy it. 



And I am tempted to add, in jjarenthesis, that in ad- 

 dition to preventing economic loss, restoring animal 

 usefulness and protecting the public health, it is our 

 duty, as veterinarians, to relieve our i)atients of need- 

 less suffering. 



It is difficult to say just where the control of |iain 

 begins. In sonu' lines of work, we n.se sedatives, aiio 

 dynes and the narcotics. Thus wjhen we ap))ly hclhi- 

 donna and menthol liniment to a gargetty ndder, or 

 when we dose a colic case with Cannabis indica or mor- 

 phine, we are relieving the patient from the apprecia- 

 tion of pain. The use of such drugs, however, is only 

 the thin end of the wedge: aJiacslihe.sia is a nmi-e ccnii- 

 plete insensibility than is thus obtained. 



Practical considerations comi)el me to speak of 

 anaesthesia nnder the conventional headings of Gen- 

 eral, Spinal and Local. 



Gcnrral aiinrstlicsiii. as usually ohtaine 1. is really 

 more than the name implies. In addition to insensi- 

 bility to pain it includesloss of consciousness : the aboli- 

 tion of reflexes and complete raviseular relaxation. 

 Now, as it is seldom necessai\y to protect the whole 

 animal against pain, these accompaniments are perhaps 

 as important as the state itself. This point has already 

 been emphasized by Muldoon (1), who gives the follow- 

 ing indications for general anaesthesia : 



1. To secure iniisculdr irla.ralion. 



(a) For the reduction of hernias and prolapses, 

 dislocations and fractures ; 



(b) To abolish cramp — particularly of the vastus 

 muscles, the so-called stifle cramp of horses; 



* Read before the Ontario Veterinarv Association, 

 Feb. 18th, 1921. 



(e) To facilitate obstetrical manipulations, the ex- 

 plorations of wounds, etc. 



2. To overcome vc'rvovs activHi/. 



In cases of strychnine poisoning, eclampsia, tata- 



nus and convulsions. 



•I. To pr/iflure insciisibilil ij for siir(jic((l openit ious. 



The means by which this state can be produced are 

 many. A blow on the head is the cheapest method but 

 is best confined to the packing houses. Of chemicals 

 we have chloroform, ether, ethyl and methyl chloride, 

 ethyl bromide, nitrous oxide and others that are best 

 administered by inhalation. By way of mouth suitable 

 doses of alcohol, chloral hydrate, morphine, hyocine 

 and cannabis indica will suffice for certain species. 

 Some of these substances can be given hypodermically 

 and intravenously. 



In choosing what agent to use, apart from the inhala- 

 tion anaesthetics, alcohol and chloral hydrate, one has 

 to make allowance for the species of animal nnder con- 

 sideration. To illustrate — morphine is narcotic and 

 anaesthetic for dogs in doses of from '4 grain upwards, 

 but it acts on fowl as an aphrodisiac and may convert 

 a eat into a maniac — at least for the time being. Small 

 doses are sedative to horses, large ones produce excite- 

 ment, ("annabis iiulica is also somewhat vai'iable in its 

 action, not so much because it tjffects the various spe- 

 cies differently, but because of the many individual 

 idiosyncrasies existing towards it. In some horses 

 it produces a narcosis so dee]i as 1o lie prai-lically aiiaes- 

 tliesia, in others the same prci)aration will cause tre- 

 mendous excitement. (2) 



Now, because it is out of place to speak of all the 

 substances that can be used for this purpose, and ot 

 I heir various actions on different kinds of aninuils, 1 

 am going to say a few words on chloroform and then 

 pass oil to other fiu'iiis of anaesthesia. 



Chlorofoi'in is easily the first choice as a general 

 anaesthetic for large animals — jjarticularly horses. 

 Tiie methods of its admin'stration you know, so I shall 

 not weary you with technical details. There are a few 

 general rules, however, which experience has taught 

 me are worth knowing and following: 



1. Jlaro xHlisfiirlorii control of your patient before 

 beginning to administer the stuff. In a nice grass pad- 

 dock with a quiet horse and a suitable muzzle, the 

 standing position is sufficient. In dealing Avith irrit- 

 able or fractious subjects, it may be the only method 

 that can be u>ed at all. Persouidly, when ))ossiblc, I 

 |)refer to ca.st tjie animal with ISaker hobbles and tiu'u 

 1 am sure that he cannot bounce around very much. In 

 this connection, let me quote from Dr. D. S. White (3) : 

 "Perfect, or even good, surgery is impossible without 

 perfect restraint. The surgeon is no better than the 

 restraint metliod which he uses . . . Imperfect 

 restraint means an imperfect operation." This general 

 truth also applies to tlie man who gives chloroform. 



2. Use onhj ihe best cliloroform obtainable regardless 

 of cost. If it is worth while using it at all, use the right 

 stuff and do your best. No matter what care is taken 

 in other respects, poor chloroform nuiy finish the 

 patient on the spot or produce bronchitis or broncho- 

 pneumonia that can easily ruillify the effects <if the 

 oi)eration perhaps a week or 10 days later. 



In this regard too, it is well to remember tliat t'veu 



