Seasonal changes in serum leptin of the feral raccoon (Procyon lotor) determined by canine-leptin-specific ELISA

Several reports have been published on blood leptin concentrations in feral animals, including members of the Carnivora, using a commercially available multi‐species radioimmunoassay (RIA) kit with anti‐human leptin antibody. However, we observed weak immunoreactivity between recombinant canine leptin and anti‐human leptin antibody, suggesting a limitation in the applicability of the RIA kit for leptin assays in Carnivora species. We tested the applicability of RIA and sandwich enzyme‐linked immunosorbent assay (ELISA) with anti‐canine leptin antibody to assay blood leptin in the dog (Canis familiaris) and the raccoon (Procyon lotor). When RIA was used for recombinant canine leptin and dog sera, values were much lower than those determined by ELISA at higher concentrations (>10 ng/ml), while rather higher at lower concentrations (