Influence of water content and the digestibility of pet foods on the water balance of cats

Abstract

Dietary adjustment has been studied for the control and prevention of the Feline Lower Urinary Tract Disease. This work studied the influence of the amount of water and food digestibility on water intake and excretion (urinary and fecal). Ten adult female cats housed in metabolic cages were used. Four treatments were tested: low price dry food, low price dry food with 50% added water, super-premium dry food and canned food. Water intake with food and by drinking, fecal and urinary water excretion and food's digestibility coefficient were determined, in a Latin square experimental design with repetitions over time. The results were submitted to variance analysis; to Tukey's test to compare means and to Pearson's Correlation to test the association between variables (p<0.05). Moist food led to the highest water intake and the largest urine volume with the lowest density. The cats balanced the higher water intake with food by drinking less water. Adding 50% water to the food did not result in a higher total water intake and urine excretion. The lowest consumption of dry matter and highest food digestibility resulted in lower fecal water excretion. Dry foods with high and low digestibility had a urine:feces water excretion rate of 0.7:1 and 1.6:1, respectively. Among the nutrients, fat intake had a positive correlation with the urine volume. Foods with higher digestibility resulted in lower fecal water loss. Canned food (high water:dry matter ratio) led to the highest total water intake and urinary volume excretion, and lower urinary density.