A|)i-il, l!l--'l. 



SCIENTIFIC AGRICULTURE. 



16' 



flic finest flilorofonii is not a very suitable coniijouud 

 and should be kept in a dark coloured bottle, or better, 

 away from the light. 



.'!. {'sr (I sijnrryi.st if the anaestiiesia is to be i)r<)liin|:red. 



Properly given, good chloroform can be administered 

 for a considerable time without danger. But less is 

 needed and the effect is greaily cidianced if flie animal 

 has been prepared by a suitab'c dose of morphine — 

 say 3 or 4 grs. hypodermically, or chloral hydrate given 

 cither per o.<t or intravenously. We con.sider it "good 

 medicine" to use synergists when prescribing to secure 

 jiurgation or some other effect. It is equally good 

 when anaesthesia is the end desired. 



I should like to digress for a moment on these last 

 two points. Three years ago Dr. Glover and I spent a 

 good many days trying to rectify some bad chloroform. 

 The only stuff issued at that particular time was fatal 

 in nearly 50 per cent of the cases to which it was given. 

 Fractional redistillation with passage of the vapor over 

 lime and some other substances reduced its deadliness 

 to about 20 per cent. P^'inally, in order to avoid poison- 

 ing even that proportion of our horses that had escaped 

 German shell fire with nothing worse than an accumu- 

 lation of assorted hardware morsels in their works, we 

 began using chloral hydrate as a narcotic giving just 

 enough chloroform in addition to produce the necessary 

 anaesthesia. This gave good results. 



As my attitude on the use of chloral hydrate (4) 

 seems to have been widely misunderstood, may I say 

 plainly that I do not propose to use it to the abolition 

 of chloroform. I decidedly prefer it to bad chloroform 

 and, under some conditions, consider it a useful adjunct 

 even to the best. 



4. Allow pli'iili/ of (ipi)i)i I iniil II far ii iihuiii /x nd 

 brcathivy. 



A beast that is trussed like a fowl with hobbles, a 

 surcingle and some one sitting on his chest has a poor 

 chance of behaving as he should. 



■"). Wtitch his hrrothiiii/. and at the first sign of ir- 

 regularity or stopping, remove the chloroform and, if 

 necessary, resort to artificial respiration. 



6. Alloiv plcnUj uf Hull', in oilier wiids chloroform 

 tile horse, don't choke him. There are two extremes to 

 be avoided, the first is giving the animal such a dose 

 of concentrated vapor that he dies from cardiac syn- 

 c<ipe, the second is consuming t.'ic iieces.sary time to lie 

 (juite safe. Hobday (o) states that 1 per cent mi.xturc 

 of chloroform vapor is pei'fcetly safe, but requires to be 

 given for an hour in order to produce anaesthesia. 

 The compromise of reason allows the animal about 10 

 or 15 minutes to reach the required stage. 



7. Have aniidnies handy in casr of rnn rijincii. 



They may not be needed, but they are like fire ex- 

 tinguishers. When you want them you want them 

 badl}\ The substances that answer the purpose are all 

 respiratory and heat .-timulants. ('am])."'ior (10 p. c. 

 in oil), stiwchnine, and atropine for h \ jjodermic use, 

 Aq. ammon. fort for in.halation and dilute hydrocyanic 

 acid (Scheeles) that may be given orally. The use of 

 the last named is specially stressed by Hobday. 



And, there is one DON'T that I should utter. Don't 

 try to chloroform an uasuitable patient. Animals weak- 

 ened from a severe respiratory disease, affected with 

 heaves, or in fat soft condition are poor subjects. Con- 

 trary to expectations perhaps, I have found fairly de- 

 bilitated horses rather good in this respect. 



I think if these rules were followed more closely, the 

 use of chloroform would be generally indulged in and 



with greater confidence. This might not be so, how- 

 ever, in general practice, because the practitioner 

 works largely alone — he cannot divide his attention 

 between the operation and the anaesthetic, he has no 

 trained assistant on whom he can depend, and he knows 

 more than to trust a novice or the owner. Moreover, 

 the extended use of local anaesthetics and narcotics, 

 or a combination of both, offers a way out of using 

 chloroform in a great many instances. So much on 

 that score. 



I mentioned s()inal anaesthesia: it seems imnecessary 

 to do more. It has been used for small animals, and, 

 experimentally, for large ones too. There is no present 

 reason to believe that this method will be of much use 

 to the general practitioner. 



Local anaesthesia, on the other hand, is a tojjic of 

 great and ever growing importance. This condition 

 and its development into regional anaesthesia is some- 

 thing with which most practitioners can iu)t afford to 

 be iinfamiliar. 



One may briefly summarize its advantages as fol- 

 lows: 



1. It is safe; 



2. Easily obtained withntit skilled as.si.staiice: 



3. Because it does not affect the respiratory and 

 digestive tracts, it may be used without dietary pre- 

 paration of the patient, without particular regard to 

 his position and without fear of general after effects. 



4. By its use the clement of surgical shock is elimin- 

 ated. 



5. It has certain special applications — particularly 

 in the diagnosis of obscure lameness, to which general 

 anaesthesia cannot be applied. 



fi. Skilfully used, in conjunction with a narcotic, it 

 enables one to jierform humanely most of the opera- 

 tions that would otherwise call for a general anaes- 

 thetic. 



Local anaesthesia may be brouglil about in a number 

 of ways. Siifficienl comjircssioii for a time will induce 

 it. though this means in practice is incidental usually 

 to tile application of a twitch. 



Cold has been made use of both by the application 

 of freezing mixtures or ice, and by the evaporation of 

 a volatile spray of ether or ethyl chloride. This refri- 

 geration, however, is superficial and not of much prac- 

 tical veterinary value. 



Finall.v, there are chemical agents. Certain of these 

 — phenol and some essential oils, are confined to exter- 

 nal use. Others con.stitute the infiltration anaesthetics 

 as typified by cocaine. Before speaking of these sub- 

 stances in any detail, I should like to review the pro- 

 perties of the ideal local anaesthetic of this class, in 

 spite of its non-existence. 



It is: 



1. Freely soluble in water. 



2. Chemically stable and devoid of certain incompati- 

 bilities. 



3. Resistant to heat up to 250 deg. F. 



4. Xon-irritant locally. 



5. Non-toxic when absorbed into the s.vstem gen- 

 erall.v. 



6. Efficient and moderately durable in its effect. 

 The first local anaesthetic of consequence to be used 



was cocaine. In certain respects it is still the best, 

 though it has some important defects when compared 

 with the theoretical ideal. It does not stand boiling, 

 and its toxicity is well known. 



Attempts to overcome these defects led to the intro- 



