Perineal findings associated with urethral ruptures on plain lateral radiographs in cats

ObjectivesThe aim of this study was to determine if there were any characteristic features of urethral ruptures (URs) on plain radiographs of cats.MethodsA retrospective, multicentre, case-control study was conducted. Radiographs including the perineum of 22 cats with UR and 70 cats without UR were blindly assessed by two reviewers, scrutinising for features including a perineal bulge, heterogeneous perineal tissue and visibility of the urinary bladder.ResultsA significant association was identified between URs and a perineal bulge (P ⩽0.003), resulting in a sensitivity of 95.5% and a specificity in the range of 38.6-47.1%, and between the presence of URs and a larger perineal bulge size (P <0.001). URs secondary to traumatic accidents were associated with a larger perineal bulge than those secondary to iatrogenic rupture. Cats with URs were more likely to have heterogeneous perineal tissue (P <0.001). There was a significant association between pelvic fractures and a perineal bulge (P ⩽0.001), but not between pelvic fractures and URs (P = 0.783). Binary logistic regression revealed associations between the reviewers' suspicion for a UR and the reviewers' recommendation for a lower urinary tract contrast study (LUTS) and a confirmed UR (P <0.001). There was no significant association between an invisible urinary bladder and the presence of a UR (P ⩾0.243).Conclusions and relevanceIdentification of a perineal bulge or heterogeneous perineal tissue in a cat may raise suspicion for a UR, especially in the absence of musculoskeletal injury, which is crucial in reducing time to diagnosis and, therefore, treatment. However, because of the low specificity, correlation with the clinical findings and confirmation or exclusion via a LUTS remains necessary. Visibility of a urinary bladder does not exclude UR.