362 



HEALTH AND DISEASE 



In entering upon the operation the bladder should be fairly distended 

 with urine, when the horse should be cast, as for the operation of castra- 

 tion. The penis and sheath are now thoroughly cleansed, and all fsecal 

 matter removed from the rectum. The administration of chloroform is 



Fig. 150." 



now proceeded with, and when the animal is fully under its influence 

 the hind-quarters are raised by under-packing with straw, and the patient, 

 having been placed on his back, is supported on either side and held 

 steadily in position. The penis is now unsheathed, thoroughly washed 

 and disinfected, and a well-oiled grooved staff (fig. 150) is introduced 

 into the urethra, and pressed carefully onwards towards the bladder by 

 an assistant, the operator guiding the course of the instrument along the 

 perineum with the left hand, while the right, which is in the rectum, 



directs the point towards 

 the bladder. By a little 

 manoeuvring the groove 

 of the staff is brought to 

 face the perineum, and 

 the assistant is instructed 

 to press the instrument 

 toward the abdomen, and 

 hold it steadily in position. 

 A scalpel is then taken in 

 the right hand, and the skin of the perineum being stretched by the left 

 forefinger and thumb, is incised along the central line from the pubic 

 arch to within an inch or less of the anus. The point of the knife 

 (fig. 151) is now forced through the walls of the urethra into the groove 

 of the staff, and an opening made according to the size of the orifice 

 required for the j)assage of the stone. A bullet-headed whalebone probe 

 (fig. 153) is now introduced into the groove, along which it is directed 

 into the bladder. 



The staff is then withdrawn, and the disinfected finger, following the 

 course of the probe, is next passed into the cavity, the probe at the 

 same time being withdrawn. 



The deeper wound, i.e. the urethral orifice, must now be enlarged 

 by extending the incision along the same line through the membranous 

 urethra. This will be effected with the least risk with the probe-pointed 

 bistoury (fig. 152), the finger in the passage acting as guide and lever 



