REG3A and alkaline phosphatase measurement: Serum PAP-1 concentration (PAP-1) has not been measured prospectively in dogs.<h4>Objectives</h4>Evaluate whether PAP-1 differentiates suspected AP (sAP) diagnosed by abnormal DGGR-lipase activity from non-pancreatic acute gastrointestinal disease (aGId) diagnosed by normal DGGR-lipase activity.<h4>Animals</h4>Twenty-six dogs with sAP, 48 dogs with aGId based on signs of acute gastrointestinal disease, lipase activity > 450 U/L (reference interval [RI],17-156 U/L) and maximally 20 U/L > RI, respectively.