Diagnostic yield of uroendoscopy compared to ultrasonography for evaluating lower urinary tract disorders in dogs

Background: Cystourethroscopy and vaginoscopy (uroendoscopy) is often used in the diagnostic evaluation of dogs with lower urinary tract disorders (LUTD). Objective/Hypothesis: To evaluate if uroendoscopy is warranted in dogs with various LUTD, the agreement between uroendoscopic and ultrasonographic diagnoses were compared. Dogs with recurrent urinary tract infections (rUTI) will have the highest diagnostic agreement between uroendoscopy and ultrasonography (US) compared to dogs presenting for other LUTD. Animals: Two hundred thirty-seven dogs presenting between 2014 and 2019 with lower urinary tract signs (LUTS) that had US within 60 days preceding uroendoscopy. Methods: Retrospective study. Dogs were categorized by primary indication for ultrasound. Pertinent uroendoscopic findings were recorded and agreements (κ analysis) between the final uroendoscopic diagnosis were compared with the final ultrasonographic diagnosis. Results: Pertinent uroendoscopic findings were recorded for 69/237 (29%) cases. For dogs presenting primarily for urinary incontinence (UI), agreement between uroendoscopy and US was 71% (46/65; κ = 0.47, 95% CI 0.28-0.66), for dogs with stranguria, 58% (29/50; κ = 0.47, 95% CI 0.31-0.62) and for dogs with rUTI the agreement was substantial at 87% (26/30; κ = 0.70, 95% CI 0.43-0.98). Urethral strictures were the majority (14/21; 67%) of pertinent uroendoscopic findings for dogs with stranguria, of which 12 were male dogs. Conclusions and Clinical Importance: Agreement between uroendoscopy and US was moderate for all dogs. Based on these data, recommendation for uroendoscopy should be tailored to individual clinical presentation and signalment; transabdominal US is not the preferred modality for urethral lesions.