Microbian invasions of the kidney that advance slowly like glanders and tubercle are further causes of chronic nephritis. Other secondary microbian infections of the kidney are complications of infectious diseases in other parts, including abscess, pyæmia, septicæmia, ulcerative endocarditis of the left heart, bronchitis, pneumonia (Fröhner), and of others less directly in the line of the circulation, as omphalitis, uterine phlebitis (Lustig), abscess of the nasal sinuses, bones, and fistulæ (Trasbot). In other cases the nephritis is evidently a result of the irritation caused by toxins in process of elimination by the kidneys, as there is no evidence of a nephritic infection. In some instances minute emboli originating in the lungs or heart, become the starting point of the nephritis, which slowly extends by reason of infection or low condition and special susceptibility. Disease of the aorta or renal artery may lead to this condition as noticed by Cadeac and Lustig. Cadeac has also noticed its association with aneurism of the mesenteric arteries so that the strongylus (sclerostoma) armatus may be considered as a factor. Again in old horses and dogs it has been associated with atheroma of the aorta and renal vessels (Trasbot). Overfeeding is not without its influence, especially when on animal food, which charges the kidneys with excreting an excess of the irritating urea and uric acid, and this is one reason why it is far more frequent in house dogs than in other domestic animals. When the meat is already decomposing and putrid there is the added evil of a quantity of toxins and even of microbes to be eliminated from the system by the much abused kidneys. Add to these that the dog’s urine is even in the normal condition more dense and contains more irritating ingredients than that of herbivora, and that owing to the slight activity of his perspiratory apparatus he can obtain less relief from the skin, and we find a substantial ground for the prevalence of chronic nephritis in this animal. Disease of the valves of the right heart or dilatation with insufficiency of the auriculo-ventricular valves is a potent cause of nephritis, the reflux of blood into the veins and the increased venous tension, speedily producing passive congestion and a slow type of inflammation in the kidney. This factor is especially liable to operate in dogs, which are particularly obnoxious to rheumatism and valvular ulceration, and are very subject to nervous cardiac disorders; in horses that have contracted heaves; and in beef breeds of cattle which suffer from fatty degeneration of the heart with dilatation. The influence of calculi must not be overlooked, whether they are lodged in the pelvis, the chalices, or the uriniferous tubules. Their tendency is to induce local irritation and exudation, with fibroid degeneration and thickening of the walls of the tubules or pelvis and of the adjacent tissue.