404 The Diseases of Animals 
retained for other reasons, a veterinarian should be 
called. It is often necessary to pass a flexible tube into 
the bladder to draw the urine away. 
STONE IN THE BLADDER 
In horses and steers, rarely in other animals, there 
are sometimes found one or more hard lumps of ma- 
terial commonly called “stones” or “gravel.” They may 
oceur in the bladder, the kidneys, or in the duct leading 
from the bladder to the outside, called the “urethra.” 
The stones or gravel are composed of salts, usually con- 
taining lime, deposited by the urine in the form of 
coneretions. They vary in size from that of shot to the 
size of an egg, but in most cases they are small and 
irregular in form. They are technically called “urinary 
ealeuli.” 
The symptoms vary, but in general there is irritation 
and difficulty in passing urine, the animal standing and 
straining after passing it. The urine often contains a 
little blood or mucus. If the bowel is emptied by an 
enema, the stones can sometimes be felt if the hand is 
passed into the rectum and applied to the bladder, which 
lies just below. Caleuli in the urinary system appear 
to be common in some localities and rare in others. 
The reason for this is not definitely known, but is 
thought to be associated with an excess of mineral sub- 
stances in the food or water. 
When the caleuli are small, in the form commonly 
called “gravel,” laxative food and a change of drinking 
water, together with a dram of citrate of lithium in the 
