THE URO-GENITAL SYSTEM 107 



clinically, but by tracing the swine that show the lesions 

 when slaughtered it is usually found that the feed of the 

 animals has been at fault. In some cases parasites and 

 calculi are responsible for the condition. 



Lesions. Chronic parenchymatous nephritic kidneys 

 are enlarged. The capsule is not easily removed, and 

 when pealed off small fragments of kidney tissue remain 

 attached to it. The kidney is mottled, due to hemorrhages 

 and infarction, and there is no definite line of demarca- 

 tion between the medulla and cortex. Microscopically 

 the parenchymatous cells are found enlarged and cloudy, 

 but tube casts are rarely observed. 



Chronic interstitial nephritis is characterized by 

 fibrous proliferation. The newly formed fibrous tissue 

 may or may not cicatrize. The gross appearance of the 

 kidney varies according to the amount and disposition of 

 fibrous tissue. If the condition is localized according 

 to the distribution of small arteries the fibrous tissue will 

 occur in foci, and spotted kidney is the result, the white 

 spots being masses of fibrous tissue. If this fibrous 

 tissue is uniformly deposited throughout the kidney and 

 does not cicatrize, the kidney is enlarged, dense, and 

 hard one of the types of the large white kidney. Granular 

 kidneys are the result of the proliferation, and later 

 cicatrization, of fibrous tissue in and around the glomeruli 

 or tubules. Granular kidneys have rough, small pro- 

 jections thickly studded over the surface; such kidneys 

 are usually of a red color. The extensive proliferation 

 and cicatrization of fibrous tissue in all the cortical 

 substance, when associated with a thickening of the 

 capsule, produces the small, hard, or sclerotic kidney. 

 Microscopically excessive quantities of fibrous tissue are 

 found, and the parenchymatous tissue is diminished, due 

 to pressure atrophy. Sometimes there may be large 

 areas of fibrous tissue in which no parenchymatous tissue 

 appears or only remnants of tubules or glomeruli. 



Symptoms. Records of the clinical evidence of 

 chronic interstitial nephritis in swine are wanting. Swine 



