The goal of this study was to measure immunoglobulin G4 (IgG4) concentrations and to evaluate the significance of these values in the management of canine pancreatitis. The medical records of 24 dogs that visited the Veterinary Medical Teaching Hospital between December 2016 and June 2018 were retrospectively reviewed to identify dogs that had been diagnosed with pancreatitis. The serum C-reactive protein and serum IgG4 concentration in the affected dogs were highly increased compared to the healthy group. Particularly, serum IgG4 measured significantly higher in dogs with pancreatitis and concurrent immune-mediated disease (p < 0.05). In conclusion, increased serum IgG4 concentrations are a characteristic finding in dogs with pancreatitis. The results of this research indicate that an elevation in IgG4 has the potential of being used as a tool for the diagnosis of pancreatitis and concurrent immune-mediated disease.