48 OPERATIVE TECHNIQUE. 



In company with Dr. Clarke, the writer attempted on several 

 occasions to kill animals b}' the administration of air saturated at 

 ordinary temperature with chloroform vapour, but the experiments all 

 proved the extreme difficulty of the attempt. Where, however, the 

 animal is partially asphyxiated, as in using several of the common 

 veterinary inhalers, death can be produced in eight to ten minutes. By 

 using a special apparatus, by means of which absolutely pure chloro- 

 form vapour, without admixtitrc of air, was administered, death was pro- 

 duced in one and a half minutes. The heart's action continued for 

 several minutes after respiratory arrest. MoUer, who employs chloro- 

 form exclusively, has administered it to more than 500 horses without a 

 single accident. 



As a basis for investigation, Moller noted in each of his cases 

 the time required to produce surgical anaesthesia, the amount of 

 chloroform used, the breed, age, sex, and weight of the animal. The 

 following is a resume of the more important results. In the case of 126 

 horses (31 stallions, 38 mares, and 57 geldings) ansesthetised with 

 chloroform, the corneal reflex was abolished in an average period of 

 20 minutes by the administration of an average quantity of 28 fluid 

 drachms of chloroform ; the quantit}' per unit of body-weight was 

 I : 4000 ; anaesthesia usuall}- lasted about 20 minutes. 



Whilst in one to two years old foals 4 to 5 drachms of chloroform 

 usually produced anaesthesia in 7 to 8 minutes, the shortest time 

 observed in full-grown horses was in one case 8 minutes, in one case 9 

 minutes, and in two cases 10 minutes. Twelve of the above 126 horses 

 required 30 minutes, and four from 30 to 40 minutes. In stallions the 

 average period was 18, in mares ig, and in geldings 22 minutes. The 

 stallions on an average consumed 30 drachms of chloroform ; 7 horses 

 (3 stallions, 2 mares, and 2 geldings) took, however, less than 12^ 

 drachms ; on the other hand 18 (5 stallions, 4 mares, and g geldings) 

 required 38 fluid drachms or over. One gelding received 60 fluid 

 drachms, and an English thoroughbred 62. V fluid drachms. The average 

 age of the stallions was 5, of the mares g, and of the geldings 7 years. 



It is worth noting that the quantity of chloroform used depends 

 partly on the method of administration. Apart from the quantity lost 

 by leakage or evaporation, less is required when administration is slow 

 than when it is rapid. The quantity used, therefore, often stands in 

 inverse proportion to the pre-anaesthetic period. 



Breed seems to have little relation to the anaesthetic influence of 

 chloroform ; it neither affects the quantity required nor the pre- 

 anaesthetic interval to any appreciable extent. On the other hand, it 

 was noted that geldings on an average required considerabl}^ more 

 chloroform than stallions and mares. 



Twenty-eight horses received subcutaneous injections of 75 grains 

 morphine before administration of chloroform. In these cases the 

 average quantity of chloroform used was 24 fluid drachms, and the time 

 interval before complete anaesthesia 15^ minutes. 



