Abstract Background Feline lower urinary tract disease (FLUTD) is a common and potentially life‐threatening condition in cats, with obstructive and non‐obstructive presentations. This study aimed to evaluate tubular injury in cats with FLUTD using serum and urinary biomarkers. Methods Forty male cats were enrolled and assigned to three groups: obstructive ( n = 16), non‐obstructive ( n = 15) and healthy controls ( n = 9). Urea nitrogen, creatinine, albumin and ELISA‐based biomarker analyses (retinol‐binding protein RBP, N‐acetyl‐β‐D‐glucosaminidase NAG, neutrophil gelatinase‐associated lipocalin, cystatin‐C Cys‐C, kidney injury molecule‐1 KIM‐1 and interleukin‐18 IL‐18) were performed on serum and urine samples. The data were analysed using Kruskal‒Wallis test and Dunn's post hoc test. Results Obstructive cats exhibited significantly elevated urinary RBP, NAG, KIM‐1, IL‐18 and albumin concentrations and indexes of RBP, NAG, Cys‐C and KIM‐1. Non‐obstructive cats also showed elevations in urinary RBP and KIM‐1. Limitations The small sample size and absence of histopathological or follow‐up data limit interpretation, although post hoc analysis showed strong power for most biomarkers except Cys‐C and NAG. Conclusion Our findings suggest that both obstructive and non‐obstructive FLUTD may involve mild tubular stress. Since only a single time point was evaluated, it remains unclear whether these changes are transient or persistent. Monitoring RBP and KIM‐1 may help identify early tubular alterations and support clinical assessment, but further validation is needed.
BAYENDUR et al. (Thu,) studied this question.