Dogs with a portosystemic shunt (PSS) often have urinary abnormalities. In this retrospective study, the prevalence of urolithiasis and other urinary abnormalities secondary to extrahepatic (EH)PSS was determined from the onset of the clinical signs until the day of surgical correction of the PSS. About 67% of all dogs were presented with urinary complaints that were directly (39%) or probably (28%) related to the EHPSS. Some dogs had surgery for urolithiasis and subsequent quantitative stone analysis revealed ammonium biurate uroliths, suggesting the presence of an underlying PSS. Additionally, 77% of the dogs that did not have any urinary complaints appeared to have urinary abnormalities based on medical imaging and/or urinalysis. Overall, 70.4% of the dogs had urolithiasis. In this study, the importance of performing a complete urinalysis, supplemented with medical imaging of the urinary system in all dogs with an EHPSS is demonstrated. In addition, the importance of quantitative analysis of uroliths is stressed, as the presence of ammonium biurate may be suggestive of a PSS.