NGF and interstitial cystitis: Following FIC, urolithiasis is the second most common cause of feline lower urinary tract disease (FLUTD), often producing clinical signs that mimic those of obstructive FIC.<h4>Objectives</h4>This study aimed to assess the diagnostic utility of serum and urine concentrations of nerve growth factor (NGF) and glycosaminoglycans (GAGs) in cats with urolithiasis or interstitial cystitis, under both obstructive and non-obstructive conditions.<h4>Methods</h4>The study included 90 cats, comprising 80 cats with clinical signs of FLUTD and 10 healthy controls.