Rufus & Coco Wee Kitty pH Health Check Litter is crafted using natural tofu and pH indicator pellets. The pH indicator pellets will only change to a blue hue when elevated pH levels are detected in your cats urine. Elevated pH levels may indicate the presence of bacteria, potentially leading to urinary tract infections. For the well-being of your cat, we strongly advise consulting your veterinarian if you observe any change in the pellet colour.