Findings of canid remains in graves at different sites in the northeast of the Iberian Peninsula are evidence of a widespread funerary practice that proliferated between the end of the 3rd and the 2nd millennium BC, in particular, in the Early-Middle Bronze Age contexts. The discovery of four foxes and a large number of dogs at the sites of Can Roqueta (Barcelona) and Minferri (Lleida) respectively, stand out among the many examples of these types of grave goods. In this work, we have made an approximation of the relationship between humans and canids through the study of their diet by analysis of stable isotopes of carbon and nitrogen in bone collagen. These analyses were complemented by archaeozoological, anthropological and archaeobotanical studies. The comparison of human and animal diets comprised a total of 37 canids, 19 domestic ungulates and 64 humans. The results indicate that the diet of the dogs was similar to that of humans, although delta N-15 values of dogs in Can Roqueta and Minferri are, on the average, 1.4 parts per thousand and 1.1 parts per thousand, respectively, lower than those of humans. The offset between canids and the herbivorous ungulates of each site is not up to the established minimum for a trophic level, which implies an input of C3 plants and human intervention in the feeding of dogs and some of the foxes. Some particular cases in Can Roqueta suggest a specific food preparation, richer in cereals, for larger dogs (probably devoted to carrying loads), and possibly for at least one of the foxes.