402 The Care 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 

 occur 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 

 concretions. 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 

 calculi." 



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. Calculi 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 calculi 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 



