OBJECTIVE To describe the ultrasonographic appearance of the urinary bladder incision site in dogs that underwent cystotomy for treatment of urolithiasis. DESIGN Prospective, longitudinal study. ANIMALS 18 client-owned dogs. PROCEDURES Dogs underwent urinary bladder ultrasonography at baseline (≤ 1 day before surgery) and at 1 day and approximately 2, 6, and 12 weeks after cystotomy for urocystolith removal. A baseline ratio between ventral (cystotomy site) and corresponding dorsal midline wall thickness was calculated and used to account for measurement variations attributable to bladder distension at subsequent visits. Patient signalment, weight, medications administered, urocystolith composition, and culture results were recorded. Clinical signs, reoccurrence of hyperechoic foci, and suture visualization were recorded at follow-up examinations. Variables were evaluated for association with cystotomy site thickening and resolution of thickening. RESULTS Median wall thickness at the ventral aspect of the bladder was significantly greater than that of the corresponding dorsal aspect at baseline. Cystotomy site thickening peaked 1 day after surgery and decreased at subsequent visits in a linear manner. Twelve weeks after surgery, 5 of 10 clinically normal dogs evaluated had persistent cystotomy site thickening. Eleven of 18 dogs had reoccurrence of hyperechoic foci within the bladder at some time during the study (median time to first detection, 17 days after surgery). CONCLUSIONS AND CLINICAL RELEVANCE Persistent cystotomy site thickening can be present up to 3 months after cystotomy for urolithiasis in dogs without lower urinary tract signs. Reoccurrence of hyperechoic foci in the bladder, although subclinical, was detected earlier and at a higher rate than anticipated.