402 DISEASES OF THE KIDNEYS 



urine an operation may be indicated. Rupture of the bladder 

 or ureters should receive immediate attention and the torn 

 or injured part sutured. 



CALCULI IN THE KIDNEY. 



Nephrolithiasis. 



Definition.— The presence of urinary stones in the pelvis 

 of the kidney. 



Etiology.— Calculi in the renal pelvis are not frequent in 

 small animals. They are far more common in the bladder. 

 The principal condition for the formation of urolithic deposits 

 is that the urine contains excess of salts, or that insoluble or 

 slightly soluble salts are formed in it. In the elimination 

 of these salts they become gradually deposited around some 

 foreign material. The center or nucleus of a calculus is 

 usually an epithelial cell, bit of mucus, pus, a blood cell, cast, 

 etc. In some cases the food which is rich in salts of various 

 kinds will hasten the formation of calculi. In certain dis- 

 tricts where the water is rich in mineral substances calculi 

 are more common, no doubt due to the excess salts taken 

 in and eliminated. Inflammatory diseases of the urinary 

 passages, or in retention of urine from any cause, will often 

 lead to the formation of urinary calculi by changing the 

 character of the urine and the salts contained therein. 



Pathology.— Stones in the pelvis of the kidney, if small, 

 may not produce much change in the mucosa, except slight 

 abrasion and irritation. When larger they may fill up the 

 entire calices or the whole renal pelvis, and can lead to marked 

 pathological changes such as extensive inflammation, hemor- 

 rhage, and sometimes marked distention of the pelvis. ,In 

 small animals the calculi usually consist of ammoniacal 

 magnesium phosphate, small quantities of calcium phosphate 

 or carbonate, some uric acid and its salts. Cystic calculi are 

 also occasionally seen. They are small, soft, and have a 

 shiny surface. 



Symptoms.— The clinical picture of kidney stones is very 

 similar to that of pyelitis, except the pain is usually more 



