Maintenance of hydration and excretion of various electrolytes and was
te products of protein and metabolism are two important aspects of nor
mal renal function. Renal failure is manifest by persistent urine conc
entrating deficits in the face of azotemia and/or uremia. The inabilit
y to concentrate urine coupled with gastrointesinal fluid loss often r
esults in dehydration, and therefore fluid therapy to replace volume d
eficits is a critical step in the initial management of dogs and cats
in renal failure. Once the renal failure patient is rehydrated, induct
ion or augmentation of a diuresis may be appropriate as it will facili
tate excretion of solutes that are reabsorbed and secreted by renal tu
bular cells. The response to rehydration and diuresis is an important
determinant of the prognosis for the renal failure patient.