Increasing Dietary Potassium Chloride Promotes Urine Dilution and Decreases Calcium Oxalate Relative Supersaturation in Healthy Dogs and Cats

SIMPLE SUMMARY: Bladder- and kidney stones are common in dogs and cats, and urine dilution is a strategy often used to decrease the risk of stone and crystal-formation. Pet foods containing sodium chloride (NaCl, table salt) increase drinking with the resultant dilution of urine. The salt substitute potassium chloride (KCl) is a potential alternative for patients that would benefit from dietary sodium restriction, but the effects of KCl on urinary parameters is unknown. This study fed two dry pet foods differing only in KCl to healthy dogs and cats. When fed the diet containing KCl, dogs and cats increased their water intake, and urine volume increased. The urine was more dilute, and measures of calcium oxalate stone risk decreased. A pet food containing KCl is therefore an interesting alternative to NaCl and a novel nutritional strategy for the prevention of urinary stones. ABSTRACT: Urine dilution is a strategy used to decrease the risk of crystallization in cats and dogs at risk of urolithiasis. Sodium chloride has been used in prescription diets to effectively promote urine dilution, but the effect of the salt-substitute potassium chloride (KCl) on urine parameters has not been extensively investigated. Two diets differing only in KCl (Diet A; K 0.44 g/MJ, Diet B; K 1.03 g/MJ) were fed to 17 cats and 22 dogs for seven days, followed by three days of urine collection. Urinary ion concentrations were determined by ionic chromatography, and SUPERSAT software was used to calculate the relative supersaturation (RSS) value for struvite and calcium oxalate. Water intake and urine volume increased, and USG decreased on diet B (p < 0.001). Urine concentration of potassium increased on diet B, but concentrations of all other ions did not change or decrease in line with urine dilution. Calcium oxalate RSS decreased on diet B (p < 0.05). This short-term study showed that increased dietary KCl in a dry extruded diet effectively dilutes the urine of cats and dogs and therefore offers a novel nutritional strategy for the prevention of urolithiasis. This finding is of interest for patients that would benefit from dietary sodium restriction.