Overall, our results may suggest that the upstream signaling events leading to the production of IFN-γ are expressed in the lymph nodes of dogs with CanL, but we did not find any significant variations in the expression of inducible nitric oxide synthase (iNOS) or arginase 1 (Arg1), the two main enzymes involved in NO metabolism during the infection of macrophages by Leishmania spp. This evidence concerns the gene NOS2 and infection.