Urinary pH in Cats: Evaluating a Minimally Invasive Method for Testing the Efficacy of Feeds and Supplements Formulated to Modify Urinary Acidity

Abstract

Urolithiasis, or the presence of calculi in the urinary tract, is one of the main causes of feline lower urinary tract disease. These calculi may form when urine is oversaturated with specific calculogenic crystalloids. Urinary pH seems to influence solubility of these crystalloids. A favourable urinary acidity may prevent, or in some cases even reverse, crystal formation. In response, many prescription diets and dietary supplements have been formulated to affect urinary pH, but studies proving the efficacy of these products often are not available. The aim of this pilot study is to test a minimally invasive method for evaluating the effect of oral supplements and prescription diets on urinary pH in the cat. Eight cats were given six subsequent interventions: dietary supplements potassium citrate, Urical, Vétoquinol urinary paste and ascorbic acid, and prescription diets Royal Canin S/O and Hill’s W/D. Spontaneously voided urinary samples were collected using modified litter boxes, and urinary pH was measured using both a benchtop pH meter and commercial test strips. Unfortunately, the current study design proved to be inadequate to test the efficacy of interventions. Urinary pH showed large variations between and within individual cats, likely due a relatively small amount of collected samples and a lack of consistency in the time of voiding. For future research, we strongly recommend creating day curves for urinary pH using a more reliable sample collection method, to allow for a more detailed comparison of changes in pH value over the day with or without interventions.