RETN and obesity due to melanocortin 4 receptor deficiency: The data obtained in the present study indicate that obesity in female dogs was also associated with the malignancy potential of tumors, as evidenced by a pronounced cell proliferation, since a larger number of Ki-67 marked cells was observed in the group of obese dogs, the same group that presented higher concentrations of resistin and a larger number of cases with histopathological graduation II.