38 CANLXE AND FELINE SURGERY 



in order to be thoroughl)' prepared to administer antidotes 

 in case of accidents. An animal may be kept in this stage 

 for any reasonable length of time. The longest period in 

 which the author has kept a dog under chloroform has been 

 four hours, but very few of the operations of daily practice 

 require an anaesthesia of more than half an hour. 



Sig-ns of Dangcer. — The. aiursthctist must devote his whole time 

 and attention to his work, and not be watching the operator. He 

 must note particular!}' the efforts of respiration ; should these 

 become weak, shallow, irregular, or in any way spasmodic, 

 or should they cease suddenly, the mask must be at once 

 removed and antidotal measures adopted. The pulse is not 

 such a good guide to danger, but extra care must be taken 

 if it become irregular, jerky, intermittent, or feeble. The 

 temperature of the body must be taken into consideration in 

 very prolonged operations, the effect of the anaesthetic, com- 

 bined with the stillness of the body, causing a fall below 

 normal. This should never be allowed to get below 95'' F. 

 Another sign which is dangerous is a convulsive twitching of 

 the extremities, especially marked in the paws of the hind- 

 legs, and in the cat it invariably means death if the hairs of 

 the coat suddenly turn the wrong wa}-. 



The respiration, however, is the cliicf, and also the easiest, tiling 

 to watch. 



Out of an experience of a very large number of dogs and cats destroyed 

 with chloroform gradually administered, in fully 95 per cent, the respira- 

 tion has perceptibly been the first to fail. Occasionally the heart has 

 appeared to cease first, or the two have appeared to stop together, this 

 being particularly noticed when the vapour was rapidly administered in a 

 concentrated form and insufficiently diluted with air, but in each case 

 where the thorax was at once opened the heart was still perceptibly beat- 

 ing.i The phonendoscope, an instrument devised particularly for listening 

 to chest sounds, is of great service in demonstrating these points. 



1 Journal of Compai-ative Pathology aitd Therapeutics, vol. viii,, p. 287, 

 ol. xi., p. loi. 



