OBJECTIVE To evaluate different methods of monitoring body temperature in anesthetized dogs with comparison to core temperature obtained via esophageal probe. METHODS Client-owned dogs undergoing general anesthesia for various procedures were included in this observational study. The temperature was taken sequentially every 10 minutes from the rectum, axilla, and nasal cavity with a digital thermistor thermometer, and compared to esophageal core temperature via paired t-tests. Differences from the gold standard esophageal temperature were assessed via Bland-Altman plots and further evaluated for factors like time under anesthesia and presence of Hypo-/Normo- or Hyperthermia. In addition, it was analyzed whether a correction factor for peripheral measurement sites (nasal cavity and axilla) would be applicable in a reliable representation of the body temperature. The level of significance in all tests was set at p<0.05. RESULTS In this study, 95 simultaneous temperature measurements at the 4 different sites were obtained from 30 dogs. Mean difference and limits of agreement from esophageal temperature for the different measurement methods were 0.0±0.72°C for rectal temperature, -1.2±1.42°C for axillary and -1.0±2.02°C for nasal temperature. Axillary and nasal temperatures were not significantly different (p=0.5721 and p=0.9287, respectively) from esophageal temperature with a +1.2°C and +1°C correction factor, respectively. CONCLUSIONS During perioperative temperature measurement in anesthetized patients, rectal and esophageal measurements can be used interchangeable. However, if these are not available, the use of axillary or nasal sites is only reliable after applying a correction factor.