Etiology, Anatomical Changes. 997 



and new-formation of connective tissue, while atrophy of the 

 new-formed tissue does not occur. 



The differentiation of chronic non-indurative nephritis from the 

 chronic inflammation, with which atrophy of the new-formed tissue 

 is associated, appears justified for the reason that these two forms 

 of renal inflammation differ essentially not only pathologically but 

 also clinically, and because the chronic indurative nephritis not in- 

 frequently develops from the commencement as such. 



Historical. The reports in veterinary literature concerning chronic 

 non-indurative nephritis are very scant and the available information 

 on this form of inflammation of the kidneys is less complete than is 

 the case in other forms. Hable, Verheyen, Thomassen, Zimmermann, 

 Marcone, Dell'Acqua, Boudoire, have reported eases belonging in this 

 category. 



Etiology. In certain cases the chronic nephritis develops 

 out of the acute form and is therefore caused by the same 

 injurious influences (see p. 989). Similar causes are of im- 

 portance, however, also in those cases in which the chronic 

 inflanunation develops as such from the start, except that they 

 exert their injurious action with slighter intensity but for a 

 longer period. Here also irritating substances must therefore 

 enter into consideration in the first place; and among these 

 especially bacterial toxins which are formed in certain pro- 

 tracted infectious diseases (chronic endometritis, chronic in- 

 fectious bronchitis, pneumonia, pleurisy, intestinal ulcers, 

 tuberculosis, glanders), and which are eliminated by the kidneys 

 after their absorption into the blood. Chronic nephritis may 

 also develop in the vicinity of purulent foci in the "kidneys 

 (Kitt). Finally it can hardly be denied that repeated taking 

 cold also will occasionally lead to chronic inflammation of the 

 kidneys. 



Anatomical Changes. As a rule the kidneys are found en- 

 larged and on pealing off the capsule, the internal surface of 

 which is more or less mottled, small shreds of renal substance 

 adhere to it. Both the outer and the cut surfaces of the kidney 

 contain red, yellow and gray spots, and likewise occasional 

 small hemorrhagic foci. The substance of the kidney is moist, 

 and if the disease has lasted for some time it is firmer than 

 normal, the medullary substance is poorly defined, wine-red, 

 dirty red and full of blood and fluid. 



TJnder the microscope the same changes may be ascertained as in acute diffuse 

 nephritis (see page 991), but with this difference that a new-formation of nucleated 

 connective tissue is often met with in the territory of the cellular infiltration. 



In the majority of cases general anemia and emaciation 

 are present, also serous effusions into the body cavities and 

 the subcutaneous connective tissue, and sometimes hypertrophy 

 of the heart muscle. 



