FRONTLINE Plus for Large Dogs (45-88 lbs) Flea and Tick Treatment 3 DosesFRONTLINE Plus for Large Dogs (45 88 lbs) Flea and Tick Treatment 3 Doses. Give your four legged friend the relief that they need with FRONTLINE Plus for Large Dogs Treatment 3 Doses. It s highly trusted by veterinarians for nearly 20 years. Made with two tough killing ingredients fipronil and (S) methoprene this flea and tick prevention for large dogs is highly effective. The first one works to eliminate the adults and the second works to destroy the