Any indication of urinary trouble, and especially with dropsy, weakness, flabbiness and anæmia and a subnormal temperature, should lead to examination of the urine, as a crucial test. A high density is good ground for suspicion. But this is not constant. In advanced cases (chronic interstitial nephritis, small white kidney, atrophic nephritis) it may be 1015 to 1025, in exceptional advanced cases with polyuria, it may be 1010, 1005, or even 1001. With such a condition, however, there is great anæmia, pallor of the mucosæ, and prostration. Tested with nitric acid and heat, the urine throws down an abundant precipitate of albumen. Under the microscope it shows a profusion of granular, degenerating epithelial cells, and casts of the uriniferous tubes.
Progress. The course of the disease is usually slow, extending over several months, but with a tendency to constant advance. The thirst increases and the urine increases in amount, clearness and levity. There may supervene extreme sluggishness, dropsies, anæmia, and weakness, irritability of the heart, and palpitations on slight exertion. So long as the heart’s action is strong, elimination may be maintained and life prolonged for months (in cow, Dickinson), or years (Friedberger and Fröhner). When the heart’s action becomes weak, elimination is rendered imperfect and the animal shows catarrh of the lungs or bowels (common in dogs), local inflammation of the lungs, pleura or pericardium, or œdemas, or hæmorrhages. The toxic effect on the nerve centres is shown by stupor or lethargy, or vertigo. When an abscess forms it is associated with a temporary rise of temperature (Trasbot). The patient may die in convulsions, in a state of coma, or by gradually advancing debility and failure of the heart.
Lesions. In cases of comparatively short standing the kidney is usually of full size, or somewhat enlarged, with firmly adherent capsule and rough or even nodular surface. The surface of the cortex may be red or grayish or parti-colored, pink and gray. The cortical portion is firm and it may even be attenuated somewhat, while the medullary portion, naturally lighter, has often grayish streaks converging toward the hilus. When the gray streaks are scraped with the knife a serous fluid, mixed with fatty granules or globules, is obtained. The glomeruli may be still about the normal size with some increase of the epithelial tuft cells. The tubules contain casts (colloid, hyaline, granular), and their epithelium normally columnar, are flattened down to cubes and are swollen, granular or fatty.
In cases of older standing the connective tissue has usually undergone a marked increase. The capsule is thick, dense and adherent. The cortical substance is shrunken with a great increase of the fibrous elements, and the same holds true of the medullary portion. In consequence of this, even in the cortical substance the white or gray color predominates. The parenchymatous tissue (glomeruli, tubules) have greatly shrunken. In connection with the contraction of the forming fibrous hyperplasia, there is a general shrinkage of the kidney in size, it may be to one-half its original volume. Trasbot reports a case of nephritis, of 8 months standing, in the dog, with a kidney half the normal size. In the end the parenchyma may have practically disappeared, and the kidney may have shrunken to a small, firm, white, fibrous mass. Abscess of the kidney is exceptionally met with (Laurent, Lafosse).
Lesions of distant organs are not uncommon. Bronchitis, pneumonia, pleurisy, insufficiency of the tricuspid or mitral valves, dilated heart, hypertrophied or fatty heart, congested or fibroid liver, arteritis, and dropsies are among such morbid conditions.
Prognosis. This is almost always unfavorable. Death may be delayed for months or years, and partial transient recoveries may take place but a restoration to normal structure and function is not to be looked for.
Treatment. This cannot be expected to be much more than palliative. The avoidance of overwork, and of the exposure to cold and wet, and the securing of a free action of the skin by warm buildings and clothing, are essential. The diet should be easily digested and non-stimulating, for herbivora green food, carrots, roots, apples, silage, with a moderate allowance of oats to counteract weakness and anæmia; and for carnivora, milk, buttermilk, mush made of oat, wheat or barley meal, with, if necessary, a slight allowance of tender raw meat. Tonics fill a similar need. Iron and bitters may be combined. Or hydrochloric acid or nitromuriatic acid with bitters (nux, calumba, salicin, quassia) may be tried. These acids are especially valuable when the case has originated in or is maintained by calculi, indigestion or hepatic disorder. When the heart is defective in tone, it may be stimulated by small doses of digitalis, strophanthus, sparteine, caffein, or nitro-glycerine, or to a certain extent by strychnia or nux. These, however, must be used with judgment, if it is found that they aggravate the case by increasing the arterial tension. In those cases in which there is an excessive secretion of watery urine, the possible source of this in musty aliment should be avoided, and the flow checked by nux vomica, in moderate doses, and bromide or iodide of potassium in full doses. When, on the other hand, the urine becomes scanty and dense, the great danger of a toxic action must be met by agents that favor excretion. Pure water at will is perhaps the least objectionable of such agents, but potassium or sodium acetate or citrate, or even sodium chloride, in weak solution, may be given. In some cases benefit will come from a moderate use of the balsam of copiaba, or the leaves of buchu, which may improve the tone of the secretory elements. The most promptly effective of these agents is pilocarpin (Friedberger and Fröhner), but it has the serious drawback of inducing profuse and dangerous depletion and debility. Yet in careful hands, and with good cardiac tone, it may often be used to advantage.
Fomentations over the loins, warm baths and mustard embrocations, may at times be beneficial. Attempts have been made to check the hyperplasia by the use of arsenic, mercury or the compounds of iodine, but their use in such cases is based on theory rather than accomplished results.
HYPERTROPHY OF THE KIDNEY.
Hypertrophy of both kidneys has not been recorded in domestic animals. On the other hand the extraordinary development of one in compensation for the loss or atrophy of the other is not uncommon. In this the organ follows the general law of adaptation, seen in the double symmetrical organs (testicle, etc.) and the more so that its functional activity is indispensable to life. Among causes are: blocking of an ureter by calculus, worms, neoplasm, nephritic abscess, gangrene, etc. The enlargement of the remaining kidney is a vicarious act and essentially a physiological one.