PSIII-36 Increased viscosity enhances water intake and reduces risk of calcium oxalate stone formation in cats

Abstract

Abstract The control of liquid intake in cats is especially of interest as there is a significant risk of urinary tract stone formation due to their high urinary solute density. Calcium oxalate stone formation is not easily mitigated by dietary manipulation. This study investigated if increasing water viscosity (282 vs 2.9 centipoise; means throughout are viscous water followed by control cats) improved voluntary intake of water and calcium oxalate stone risk. Twelve cats (7 neutered males, 5 spayed females) from 3 to 8 years of age with an average weight 4.7 kg were monitored for 4 months. Each cat spent 2 months consuming viscous water and two months consuming normal water in a crossover design. Water consumption was measured through loss of weight from each pet’s water bowl with an additional bowl of the consumed viscosity placed in the room for evaporative loss measurements. A urine calcium oxalate titrimetric test (COT) was performed to evaluate the risk of calcium oxalate stone formation. In brief, the [Ca+2]/(added Oxalate-2) ratio is calculated (per liter). An increasing index value denotes samples at greater risk of calcium oxalate crystallization. The ratio represents the concentration of ionized calcium and the amount of oxalate that is added to initiate crystallization. The results showed that cats drinking viscous water had a significant increase in water consumption (79.9 vs 65.6 grams P = 0.014). There was a reduction in urine specific gravity (1.042 vs 1.052 P = 0.016), fractional excretion of calcium (0.197 vs 0.280 P = 0.036), urinary calcium concentration (49.8 vs 61.8 ppm P < 0.01) and in stone risk as measured by COT (35.5 vs 82.4 P = 0.029). In conclusion, these data show that there is an increased intake of water when cats are offered water with increased viscosity and increased viscosity was associated with an improvement in measurements of oxalate stone risk.