The Montenegro skin test is widely used as a diagnostic method for American cutaneous leishmaniasis (ACL). However, there is little information about the histological changes that occur after administration of the antigen, especially in dogs. Two intradermal reactions were used in mongrel dogs during a clinical and epidemiological study as a diagnostic method for canine cutaneous leishmaniasis at Virginópolis, Minas Gerais, Brazil. Leishvacin and P10,000G were used as antigens. The inflammatory reaction was more intense and diffuse in dogs tested with P10,000G than Leishvacin.