This study investigated the use of two commercial products, a deltamethrin-impregnated collar and a fipronil-(S)-methoprene spot-on formulation, in combination to protect dogs against sandflies and fleas when they live in or travel to leishmaniasis-enzootic areas. Interactions, tolerance, and efficacy were evaluated. The combination was well tolerated by the six treated dogs. The antifeeding effect on Phlebotomus perniciosus ranged from 89.6% (day 1) to 99.51% (day 21) and exceeded 95% from day 7 through the end of the study; the mortality effect against P. perniciosus ranged from 87.52% (day 22) to 96.82% (day 15). The combination was 100% effective in controlling Ctenocephalides felis felis infestations for 36 days after treatment. These results suggest that it is feasible and advantageous to combine these two commercial products to protect dogs against sandflies and fleas in leishmaniasis-enzootic areas.