640 PARALYSIS OF THE URINARY BLADDER. 



scarcely be introduced into the urethra itself, the fore and middle 

 fingers are passed as far as the opening and the catheter introduced 

 between them. A blind sac (Fig. 437 /) of varying size exists behind 

 or below the opening of the urethra in cows, and sometimes renders 

 the passage of the catheter difficult, the point of the instrument readily 

 passing into the sac. In stallions and geldings the operator stands 

 at the side of the abdomen on the animal's left, and draws the penis 

 forwards out of the sheath. In order to grasp it more firmly a cloth 

 is passed round the penis, and the catheter is then introduced. The 

 instrument must, however, have been previously carefully cleansed 

 to prevent the introduction of organisms into the bladder, and, to 

 allow of its easy passage, the surface should be smeared with vaseline, 

 hi the anterior sections of the urethra the catheter glides easily forward 

 under slow, steady pressure. The first difficulty is on passing the 

 bend of the urethra at the ischial arch. Here an assistant must 

 direct the point of the catheter towards the bladder by pressing 

 on it, whilst the operator thrusts the instrument cautiously on, and 

 gradually retracts the stilette. Violent movements at this stage 

 are liable to injure the urethra, and must be strictly avoided. 



Immediately the end of the catheter has passed this point it 

 again glides easily forwards, and finally attains the neck of the 

 bladder, which seldom opposes any resistance to its entrance. The 

 stilette is then withdrawn and the urine allowed to escape. 



In bulls and oxen only the forward end of the urethra as far as 

 the " S "-shaped curve can be catheterised, and even this seldom 

 becomes necessary. The same is true of rams, though in them the 

 entrance is rendered still more difficult by the vermiform appendix. 

 In case of need, the appendix may be cut off or the urethra incised 

 behind this point (see " Urethrotomy in Ruminants "). 



Catheterisation is easiest in the dog. The animal is placed on 

 a table in the dorsal position, with the left side towards the operator. 

 The penis is then exposed by the method described under " Urinary 

 Calculi in the Dog," and the catheter, previously carefully prepared, 

 passed into the urethra. To prevent injuring the canal at its curve 

 over the ischial arch, the instrument is passed as far as this point, 

 and the stilette then drawn back at the same rate as the catheter 

 advances ; when the bladder is reached, the stilette is removed 

 entirely. 



By means of the catheter not only can decomposed urine, &c, 

 be removed, but fluids may, if necessary, be introduced into the 

 bladder and its mucous membrane directly treated. Baertz, in a 

 case of strangury, injected infusion of belladonna with good results. 



