Background - Few studies have investigated the frequency of urinary tract infection (UTI) in dogs receiving long-term ciclosporin therapy. Hypothesis/Objectives - The goal of the study was to investigate the frequency of UTI in dogs receiving ciclosporin with or without glucocorticoids. A secondary goal was to determine whether bacteriuria, pyuria and urine specific gravity were good predictors of UTI, and if ciclosporin dose, concurrent ketoconazole therapy, sex or duration of therapy affected the frequency of UTI. Animals - Eighty-seven dogs with various inflammatory skin disorders and 59 control dogs with inflammatory skin conditions that had not received glucocorticoids or ciclosporin for 6months were enrolled. Methods - This study was retrospective. The first urine culture from dogs receiving ciclosporin was compared with control dogs using Fisher's exact test. A logistic mixed model was used to test for association between a positive bacterial culture and duration of treatment, dose of ciclosporin, concurrent ketoconazole therapy and sex. The sensitivities and specificities for bacteriuria, pyuria and urine specific gravity were determined. Results - Twenty-six of 87 (30%) ciclosporin-treated dogs had at least one positive culture. Compared with 3% positive control samples, 15% were positive in treated dogs (P=0.027). The sensitivity and specificity were, respectively, 64.1 and 98.1% for bacteriuria, 74.4 and 70.9% for pyuria, and 56.4 and 65.3% for urine specific gravity. All other analysed parameters were not significantly different. Conclusions and clinical importance - The results suggest that routine urine cultures and assessment of bacteriuria by cystocentesis should be part of the monitoring for dogs on long-term ciclosporin with and without glucocorticoids.