Cyphenothrin is one of the type II pyrethroid insecticide, in combination with fipronil it used to provide dogs with protection to common topical parasites in dogs. Cyphenothrin primarily affects sodium channels in excitable membranes causing a prolongation of the sodium current during excitation. The prolonged sodium current results in the development of a depolarizing after potential following the action and is responsible for the induction of repetitive activity, which is the most characteristic effect of pyrethroid poisoning in the nervous system. At low concentrations, insects and other arthropods suffer from hyperactivity. At high concentrations, they are paralyzed and die.