[Clinical studies of kidney function in sheep. II. Effect of pregnancy, lactation and feed restriction and metabolic diseases on kidney function].

Investigations of renal function have been done in healthy ewes in different stages of reproduction, and after food restriction, as well as in ewes sick with ketosis, hypocalcemia, rumen acidosis and different nephropathies. The determination was based on the estimated weight dependent endogenous creatinine excretion (E). A reference population of 56 healthy non or early pregnant ewes (before day 120 of pregnancy) was used as control. Late pregnancy (121.-149. day, n = 14) and lactation (n = 14) lead to higher renal creatinine-clearance (approximately GFR). Food restriction in all stages of pregnancy was followed by lower plasma concentrations of potassium, calcium, magnesium and glucose, and a reduced fractional excretion of potassium, calcium and magnesium. Pregnancy and especially food restriction caused a marked rise of the 3-OH-hydroxybutyrate values in the plasma and a significant acetonuria. After withdrawal of feed in lactating sheep, in opposition to pregnant sheep, the plasma values of phosphate were higher. In ketotic sheep (n = 43) a failure of renal function could not be demonstrated, the pronounced acetonuria could be explained by acetonemia. In hypocalcemia (n = 23) disturbance of creatinine-clearance and tubular reabsorption of sodium, potassium, glucose and 3-OH-butyrate could be seen. Glucosuria and acetonuria were caused by increased plasma concentrations and reduced tubular reabsorption. In rumen acidosis (n = 10) disturbances of low degree of GFR and reabsorption could be seen, glucosuria was mainly due to hyperglycemia.(ABSTRACT TRUNCATED AT 250 WORDS)