The radiographic appearance of the urinary bladder in guinea pigs (Cavia porcellus) affected by cystitis is poorly characterized. This retrospective case–control study assessed the radiographic characteristics of the urinary bladder (digital abdominal and whole-body radiographs) in 24 healthy guinea pigs and 24 guinea pigs diagnosed with cystitis. Inclusion criteria for the cystitis cohort included presence of clinical signs (hematuria, incontinence, stranguria, abdominal discomfort, apathy, and inappetence), leukocyturia and/or bacteriuria, complemented by right lateral radiographs and either ultrasound or a positive urine culture. Radiographic criteria indicative of cystitis were systematically evaluated using a vertebral bladder score (VBS) expressed in lumbar vertebral units (LVU) and reference marker lines on lateral radiographs to assess urinary bladder distension. Compared to the control group, radiographs of guinea pigs with cystitis demonstrated increased bladder opacity (46% of cases) and solitary uroliths (25%). Bladder height in patients with cystitis exceeded that of healthy counterparts (median: 16.6 vs. 13.0 mm). The VBS in the cystitis group was significantly elevated (median: 1.50 vs. 1.20 LVU). This investigation revealed that enhanced bladder distension and increased bladder opacity, with a VBS surpassing 1.3 LVU, correlated with the presence of cystitis.
