Etiology, Anatomical Changes. 1003 



by periodical disturbances in the outflow of urine, and this 

 factor probably is preferably active in ruminants and hogs. 



The chronic nephritis which has been observed frequently in buffaloes in Hun- 

 gary (Schoppelt, Vamos) is perhaps caused by renal gravel or by periodical inter- 

 ference with the outflow of the urine. The facts that the affection is often uni- 

 lateral or that one kidney' is involved far more extensively, and still more the 

 atrophy with dilatation of the calyces which is observed in sections of the kidney 

 that show only slight morbid changes, are certainly in favor of the urogenic origin 

 of the process. , 



Anatomical Changes. Indurative nephritis is characterized 

 principally by the increase of the connective tissue and there- 

 fore by a firmer consistency of the organ (Nephritis indurativa, 

 Sclerosis renum). Later on the kidney becomes smaller and 

 its surface uneven, in consequence of variable depressions. 



On histological grounds Kitt distinguishes the following forms: 



Nephritis fibrosa multiplex s. Sclerosis maculata. This occurs 

 in cattle, in hogs and dogs and is characterized by yellowish or gray- 

 white furrows on the surface of the kidney, and by white wedge-shaped 

 foci in the cortical substance, which consist of fibrous connective tissue, 

 round cells, and isolated urinary tubules with disintegrating epithelia. 

 These changes are probably due to embolism and may sometimes develop 

 out of nephritis purulenta disseminata. Degen, for instance, showed 

 by careful examinations that purulent nephritis which in hogs usually 

 is hematogenic, generally leaves the evidences of nephritis fibrosa multi- 

 plex on healing. 



Nephritis fibrosa diffusa is an inflammation which is about evenly 

 distributed over the entire kidney, which is very large, firm to the touch 

 and, in the calf, sometimes calcified. White, yellowish-white and yellow 

 islands alternate and any remaining healthy tissue is only indicated 

 by brown-red streaks. The ground substance consists of fibrous tissue 

 which is poor in cells and in which few urinary tubules are imbedded ; 

 the latter contain only occasional normal epithelial cells but much 

 granular detritus. The glomeruli and the vicinity of the thick-walled 

 capsules show cellular infiltration. 



The unequal atrophy of the proliferated connective tissue causes 

 shallow depressions on the surface of the kidneys, which therefore 

 appears finely or coarsely granular (Nephritis granulosa) and at the 

 same time the kidney becomes smaller (Atrophia granulosa). By the 

 contraction of the connective tissue some urinary tubules are constricted 

 in places, others are obstructed by masses of disintegrated epithelia 

 and by casts, and in consequence the urine is dammed up above the 

 constricted or obstructed places, leading to dilatation of the tubules 

 and of the corresponding capsules of Bowman, which then are gradually 

 transformed into small retention cysts (Nephritis fibro-vesiculosa) . 



Symptoms. Chronic indurative nephritis has only rarely 

 been observed clinically, and it is therefore as yet impossible to 

 describe its clinical picture exhaustively. The want of complete 

 clinical knowledge is particularly great in the indurative nephri- 

 tis of ruminants and hogs. The urinalyses made by Vamos in 



