558 OPERATIONS ON THE GENITO-UEINARY APPARATUS. 



inches in front of the vulva. WhUe thus holding- the instrument, 

 he feels, with the middle finger of his right hand, for the mucous 

 valvular fold which covers the meatus, pushes the finger under it, 

 and then, bringing the bulb end of the catheter to the opening of 

 the urethra, inserts it into the bladder. 



The accidents that may arise from carelessness, or otherwise, 

 in the catheterism of males, are not met with when treating 

 females. 



UKETHKOTOMY. 



Incisions of the urethral canal are made for various purposes. 

 The removal of foreign bodies, usually calculi ; the restoration of 

 the suspended power of micturition when is has been caused by 

 the closure of the passage ; the estabhshment of an artificial 

 urethral opening ; and the penetration of the cavity of the bladder 

 when necessary for surgical j)urposes — these are among the 

 reasons for which this important canal is incised by the surgeon. 

 It is principally performed on males, the dimensions, aside from 

 its shortness, of the urethra in females being, as a rule, ample, 

 and the organ sufficiently dilatable for the removal of calcuh, 

 or other objects, without invohing the necessity of an operation. 

 Among the males, the ox is the animal which most frequently re- 

 quii-es it, by reason of the peculiar Hability of this animal to suffer 

 from a constitutional tendency to the formation of calcuH and 

 the fact that these accretions are often arrested in the urethra, in 

 consequence of a peculiar double curvature, or S formation, in the 

 penis. 



With horses, it is in some districts quite a common operation. 

 In these animals, however, the calculi, though of rare formation, 

 are larger and are more generally retained, either in the bladder 

 or in the first portion of the urethra. In smaller animals, calculi 

 are also quite common and troublesome, esj)ecially in dogs, on 

 account of the presence of the bony formation in the structure of 

 the penis. 



In the horse, the principal operation is performed in the peri- 

 neal region, or the part extending on the median hne from the 

 anus to the scrotum, bounded above and on each side by the 

 ischial tuberosities, and below by the flat of the thighs. 



The skin of the perineum is very fine and thin, and is hairless 



