Bladder stones are collections of mineral crystals that combine together in the urinary tract. They can cause discomfort and lead to more serious problems that require the care of a veterinarian.Hill's nutritionists & veterinarians developed Prescription Diet® s/d clinical nutrition to support your cat's urinary health. In fact, s/d is clinically tested to dissolve struvite stones in as little as 6 days (average 13 days).