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.
If compensation is perfect, it may be impossible to detect symptoms
apart from those of the primary disease.
_Prognosis._ Life is endangered in case of any subsequent kidney
disease.