ShieldTec Plus for Dogs provides superior protection against flea, tick, and mosquito at an affordable price. ShieldTec Plus for Dogs harnesses the power of two active ingredients. The primary ingredient kills and repels adult fleas, ticks, mosquitoes, and lice, while the other ingredient, an insect growth regulator prevents new infestations by destroying eggs and larvae. ShieldTec Plus for Dogs also protects against blood-feeding mosquitoes, a vector of heartworm. Each package contains four- dose, each dose lasts for up to four weeks for a total of four months of protection.