.

LONGITUDINAL SECTION THROUGH KIDNEY.]

[Illustration: PLATE IX.

MICROSCOPIC ANATOMY OF KIDNEY.]

[Illustration: PLATE X.

MICROSCOPIC ANATOMY OF KIDNEY.]

Albuminous urine in the horse is usually glairy, so that it may be drawn
out in threads, but its presence can always be tested as follows: If the
liquid is opaque, it may be first passed through filter paper; if very
dense and already precipitating its salts, it may be diluted with
distilled water; add to the suspected liquid acetic acid drop by drop
until it reddens the blue litmus paper; then boil gently in a test tube;
if a precipitate is thrown down, set the tube aside to cool and then add
strong nitric acid. If the precipitate is not dissolved, it is albumen;
if dissolved it is probably urate or hippurate of ammonia. Albumen is
normally present in advanced gestation; abnormally it is seen in
diseases in which there occurs destruction of blood globules (anthrax,
low fevers, watery states of the blood, dropsies), in diseases of the
heart and liver which prevent the free escape of blood from the veins
and throw back venous pressure on the kidneys, in inflammation of the
lungs and pleurae, and even tympany (bloating), doubtless from the same
cause, and in all congestive or inflammatory diseases of the kidneys,
acute or chronic.

Casts of the uriniferous tubes can be seen only by placing the suspected
urine under the microscope. They are usually very elastic and mobile,
waving about in the liquid when the cover glass is touched, and showing
a uniform, clear transparency (waxy) or entangled circular epithelial
cells or opaque granules or flattened, red-blood globules or clear,
refrangent oil globules. They may be even densely opaque from crystals
of earthy salts.

Pus cells may be found in the urine associated with albumen, and are
recognized by clearing up, when treated with acetic acid, so that each
cell shows two or three nuclei.

DIURESIS (POLYURIA, DIABETES INSIPIDUS, OR EXCESSIVE SECRETION OF
URINE).

This consists in an excessive secretion of a clear, watery urine of a
low specific gravity (1.007) with a correspondingly ardent thirst, a
rapidly advancing emaciation, and great loss of strength and spirit.

_Causes._--Its causes may be any agent--medicinal, alimentary, or
poisonous--which unduly stimulates the kidneys; the reckless
administration of diuretics, which form such a common constituent of
quack horse powders; acrid diuretic plants i