36 



CANINE AND FELINE SURGERY 



in which to produce the safe stage of unconsciousness for a 

 cat or small dog is from one to two minutes ; for a dog the 

 size of a terrier, about three or four minutes ; and for the 

 larger breeds, six or eight minutes. 



Stages of Chloroform or Ether Anaesthesia.— During the 

 process of complete anaesthetization an animal passes through 

 four stages. The first one is a stage of surprise and alarm, 

 during which the patient sometimes holds its breath as if 

 unwilling to receive the strong vapour. This is especially 



Fig. 24. — The Author's Third Pattern of Inhaler showing another Form 



of Mask. 



noticeable in cats and rabbits, and care must be taken to 

 allow the respirations to become regular before proceeding. 

 The second stage is one of excitement during which the 

 animal is in a semi-conscious state, and appears in an almost 

 frenzied condition, yelping and strugghng violently, and 

 often involuntarily relaxing the sphincters of the rectum and 

 bladder. After this we get the third or safe ansesthetic stage, 

 in which the animal is ready for the operation ; and lastly 

 the fourth or dangerous stage, in which there is risk of per- 

 manently paralyzing one or more of the great vital centres. 



