BackgroundAcute pancreatitis (AP) occurs frequently in dogs, but most previous studies examining the diagnosis of AP have used data from secondary care hospitals.Hypothesis/ObjectivesThe aim of this study was to investigate the clinical utility of diagnostic laboratory tests in dogs with AP in a primary care hospital.AnimalsSixty‐four dogs with clinical signs suggestive of AP diagnosed with nonpancreatic disease (NP) or AP.MethodsMedical records were retrospectively reviewed, including diagnostic laboratory tests considered potentially useful in the diagnosis of AP. The diagnostic accuracy of amylase and FUJI DRI‐CHEM lipase (FDC lip) were investigated using receiver operating characteristics (ROC). In addition, we verified whether diagnostic laboratory tests were useful for evaluating duration of hospitalization and as biomarkers for monitoring recovery.ResultsActivities of amylase and FDC lip were significantly higher in the AP group than in the NP group (P = .001, P < .001, respectively). The sensitivity of FDP lip activity for diagnosing AP was 100% (95% confidence interval [CI], 87.7–100%); the specificity was 89.5% (95% CI, 66.9–98.7%). Area under the ROC curve for FDC lip activity was 0.98 (95% CI, 0.93–1). High alanine aminotransferase (ALT) activity was associated with extended duration of hospitalization (P = .04). A significant difference in C‐reactive protein (CRP) concentration before and 5 days after treatment was found (P = .001).Conclusions and clinical importanceMeasurement of FDC lip activity appears useful for diagnosing AP. High ALT activity might be associated with prolonged duration of hospitalization, and CRP might be useful as a biomarker for monitoring recovery from AP.