High dietary salt (NaCl) concentrations are assumed to be beneficial in preventing the formation of calcium
oxalate (CaOx) uroliths in cats, since increased water intake and urine volume have been observed subsequent
to intake. In human beings, dietary NaCl restriction is recommended for the prevention of CaOx
urolith formation, since high NaCl intake is associated with increased urinary Ca excretion. The aim of
the present study was to clarify the role of dietary NaCl in the formation of CaOx uroliths in cats. Eight
cats received four diets that differed in Na and Cl concentrations (0.38–1.43% Na and 0.56–2.52% Cl dry
matter, DM). Each feeding period consisted of a 21 day adaptation period, followed by a 7 day sampling
period for urine collection. Higher dietary NaCl concentrationswere associated with increased urine volume
and renal Na excretion. Urinary Ca concentration was constant, but renal Ca excretion increased from0.62
to 1.05 mg/kg bodyweight (BW)/day with higher dietary NaCl concentrations (P ≤ 0.05). Urinary oxalate
(Ox), citrate, P and K concentrations decreased when NaCl intake was high (P ≤ 0.05), and urinary pH was
low in all groups (6.33–6.45; P > 0.05). Relative supersaturation of CaOx in the urine was unaffected by
dietary NaCl concentrations. In conclusion, the present study demonstrated several beneficial effects of
high dietary NaCl intake over a relatively short time period. In particular, urinary Ca concentration remained
unchanged because of increased urine volume. Decreased urinary Ox concentrations might help
to prevent the formation of CaOx uroliths, but this should be verified in future studies in diseased or predisposed
cats.