PARALYSIS OF THE URINARY BLADDER. 
379 
In large male animals one large catheter generally suffices ; in clogs, 
catheters of varying calibre must be kept. For mares and dogs a 
straight or slightly bent tube with a well-rounded end is used, though 
in case of need the index or middle finger may replace the catheter. 
The introduction of the catheter is seldom difficult in these animals, if it 
be borne in mind that the outer opening of the urethra lies on the lower 
wall of the vagina, over which the instrument is allowed to glide 
forwards until it enters the urethra. For cows Imminger uses a special 
instrument about 13 inches in length and inch in diameter, with 
a pointed end and a small round head; he also employs a metal 
catheter 12 inches long and \ inch thick, slightly bent towards the 
rounded point, which is § inch long. Before commencing the cow’s head 
is firmly tied to a ring or the animal is thrust against the wall. The 
hand is wetted or oiled and passed into the vagina, where the opening of 
the urethra is soon discovered and is slightly dilated by passing the 
forefinger into it. The catheter is then passed in and slipped beneath 
the finger into the urethra and so into the bladder. As, in young 
animals, the forefinger can 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 of varying size exists 
below the opening of the urethra in cows, and sometimes renders the 
passage of the catheter difficult, especially when the urethra opens 
on the upper wall of 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 smeared with oil or water. 
This is absolutely necessary. In the anterior sections of the urethra 
the catheter glides easily forwards under slow, steady pressure. The 
first difficulty is on passing the bend of the urethra at the ischiatic 
arch. Here an assistant must direct the end of the catheter forwards 
towards the bladder by pressing on it, whilst the operator thrusts the 
instrument cautiously on, and gradually retracts the stilette. Violent 
movements at this time are liable to injure the urethra, and must be 
. strictly avoided. 
Immediately the front 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 great 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 
