FAILURE OF LOOP DIURETICS TO INDUCE NURSING SICKNESS IN MINK AT WEANING

Nursing sickness in mink is thought to be precipitated by inadequate s alt intake, whether this is due to inadequate salt levels in the diet or inadequate total dietary intake, To test this hypothesis, lactating females raising large litters were given 2 daily intramuscular inject ions of the loop diuretic furosemide (Lasix, 4 + 4 mg/kg/day) for 2.5 d during the normal weaning period 6 wk after parturition or served as untreated controls. Following the same protocol, barren mink (i.e. un successfully mated females) were treated similarly. Darns were careful ly inspected for clinical signs of nursing sickness during and after t he treatment. Urinary osmolality and concentrations of sodium, potassi um, chloride, creatinine and carbamide (urea) were measured prior to t reatment (day 1) and on day 3, immediately before and 4 h after the fi nal diuretic treatment. Plasma concentrations of aldosterone and corti sol were determined by radioimmunassay 4 h after the last injection wi th furosemide on day 3. Biochemical changes in urine (a low osmolality , low concentrations of carbamide and creatinine, and extremely low so dium concentrations) and in plasma (aldosteronism) similar to those fo und in nursing sickness were elicited in the nursing dams. Nevertheles s, none of the dams developed overt clinical signs of nursing sickness . It is concluded that the biochemical signs of volume and salt deplet ion associated with nursing sickness are sequelae rather than etiologi cal factors of this disorder.