FATTY DEGENERATION OF THE KIDNEY: STEATOSIS OF THE KIDNEY.
Causes: age, overfeeding, idleness, atony, retention of urine. Lesions: kidney enlarged, pale yellow, capsule loose, cut surface glistening unctuous, oil globules in scrapings, granules soluble in ether. Symptoms: in idle, overfed, obese, improved meat producing breeds, closely confined, starchy or saccharine food, fatty granules in urine, finally dropsies, anæmia, debility, sluggishness. Prognosis unfavorable in advanced stage. Treatment: butcher, restricted regimen, open air exercise, nitrogenous diet, crossing, diuretic food or drugs, oil of turpentine, balsam copiaba. Palliation only.
Fatty degeneration of the kidneys is by no means unknown in the domestic animals. It has been observed in dogs and cats (Rogers, Goubaux, Vulpain, Trasbot). In dogs it has been erroneously set down as a characteristic lesion of rabies. Like fatty degeneration of other organs, it is also met with in old and overfed individuals of meat producing breeds of animals, in which the tendency to early maturity and rapid and excessive fattening has been fostered from generation to generation. In man small, granular, fatty kidney is a common result of chronic parenchymatous nephritis, and often coincides with fatty liver. Chronic poisoning by arsenic or phosphorus is another cause, as it is of fatty degeneration in other organs.
Vulpain has attributed it to a lack of active exertion and of general tone, associated with excessive amylaceous feeding, sluggish, shallow breathing and tardy elimination. Goubaux and Trasbot attach great importance to the compulsory retention of urine in house dogs, cats and horses. The damming back of the urine in the convoluted tubes and glomeruli, temporarily arrests secretion, and the inactive and compressed cells tend at once to granular and fatty degeneration.
Lesions. The gland is sensibly increased in size, and pale, yellowish or straw yellow. The capsule is easily detached from the cortical substance, contrary to what is the case in chronic productive inflammation. The cortical substance is increased in thickness, and pale, the pallor being largely in ratio with the duration or extent of the fatty degeneration. The cut surface may be glistening and unctuous to the touch. It is softer than usual, rather friable, and if scraped, furnishes a serous or grayish pulp in which oil globules are prominent features, together with granular epithelium and free granules that dissolve readily in ether. Tubules are varicose and unequal at different parts. The medullary portion has undergone little change. It may be paler at certain points, with some shrinking of its substance and increase of firmness.
Symptoms. As a rule the disease occurs in pampered, overfed and obese animals, and in those of the improved breeds which have great power of digestion, assimilation and fattening. It is especially to be looked for after close confinement on full, stimulating, amylaceous diet. Symptoms are not usually recognized during life. There is, however, a lessening of the urinary secretion, and, as the disease advances, albuminuria. When examined microscopically this is found to contain characteristic elements, such as granular epithelial cells, the granules soluble in ether, oil globules, and at times crystals of cholesterine (Beale). A diagnosis based on the mere presence of oil globules may, however, be fallacious, as these may be present in animals that have just been heavily fed on oleaginous food, and again the oil used to smear the catheter may float in the urine and prove misleading. Under such circumstances vaseline or glycerine may be substituted on the catheter. Scriba induced fatty urine by injecting fat or oil emulsion into the blood, and Chabrie by ligating the large intestine. Trasbot says that cylindroid casts may be present. As in other grave kidney affections, dropsies supervene as the disease advances. These may show in the limbs, in the abdomen, or in other serous cavities. A steadily advancing anæmia with pallor of the mucosæ, listlessness, weakness, debility and sluggishness are to be noted.
Prognosis. Since the disease is rarely diagnosed until it has reached an advanced stage, it usually progresses steadily to a fatal issue. If, however, it can be detected at an earlier stage, it may be palliated, or held in abeyance, for a length of time varying with the extent of the lesions. As it is very largely a disease of meat producing animals and as the subject is at first in a condition of marked obesity, it can usually be turned over to the butcher without material loss.
Treatment. If the disease has resulted from the inbred propensity to fattening, the family that shows the disposition must be subjected to a somewhat different regimen, open air exercise must take the place of confinement in warm stables, a rather bare pasturage is valuable for herbivora, and a restricted diet in which the oleaginous, saccharine, and amylaceous constituents do not predominate, is strongly indicated. Crossing with a strange male having many of the desirable qualities of the herd, but which is more vigorous may be resorted to. When the secretion of urine becomes scanty an abundance of pure water, or a diet of succulent grass or roots or ensilage or even small doses of alkaline diuretics may be resorted to. Any source of arsenic or phosphorus poisoning should be cut off, and as an antidote to phosphorus, oil of turpentine may be given in small doses. This agent may, indeed, replace the alkalies as a diuretic, bringing in an element of tone for the mucosa which is not to be despised. Or balsam of copaiba or buchu leaves may be substituted.
When the small white kidney (granular, fatty) results from chronic nephritis, the prevention and treatment would be as for that disease. Little hope is to be entertained of entire restoration to health.