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 cats, bacterial infections are far less common. Urinary crystals and stones are often linked to this disease. The most common cause of Lower Urinary Tract Disease in cats is idiopathic cystitis. This diet promotes a urinary environment unfavorable to the development of both struvite and calcium oxalate crystals.Royal Canin