Raccoon dogs are canines that undergo excessive fattening in the autumn while during winter they endure a long fasting period. Understanding the signals regulating energy homeostasis in these animals might offer a novel perspective on the investigation of metabolic control. Five juvenile female farm-bred raccoon dogs were fasted for 10 weeks during wintertime. The six fed group (FED) animals had ad libitum access to food, but were otherwise in similar environmental conditions as fasting group (FAST). Blood samples were collected in March. Plasma cytokines, adipokines and gastrointestinal peptides were determined with canine ELISA (Enzyme-linked immunosorbent assay). FAST (9,010,44kg) had significantly lower weight compared to FED (11,190,41kg), but both groups lost weight in wintertime as FED lowered voluntarily energy intake. The plasma insulin showed a decreasing trend in FAST when compared to FED (p=0,054). Glucose-dependent insulinotropic peptide (GIP) plasma levels showed an increasing trend in FED in comparison to FAST (p=0,077). Monocyte chemoattractant protein-1 (MCP-1) is a pro-inflammatory cytokine, stimulated by plasma free fatty acid, and its levels were elevated in FAST (p=0,046). Interestingly, many established signaling molecules that affect metabolism in other species, such as adiponectin, leptin and ghrelin did not show any changes in plasma levels. The results indicate that raccoon dog is well adapted to long periods of fasting. The endocrine signals that normally affect human energy control were not changed in the raccoon dogs even after the prolonged fasting time. In conclusion, the seasonally adaptive raccoon dog has unique regulatory mechanisms to control body weight and metabolism. Supported in part by the Academy of Finland.