Lower urinary tract disease (LUTD) refers to a group of disorders that commonly leads to irritation of the urinary tract and corresponding undesirable clinical signs. What causes Lower Urinary Tract Disease? In dogs, bacterial infections of the urinary tract and the presence of stones (uroliths) in the urinary tract are the most common causes. This diet promotes a urinary environment unfavorable to the development of both struvite and calcium oxalate crystals.Royal Canin