Pyrethrins and pyrethroids

Safety of Permethrin and Pyriproxyfen in Dogs Treated With VetGuard Plus®

“…Pyrethroids, such as permethrin, exert neurotoxicity by targeting primarily the voltage-gated sodium channels of nerve cell membranes [18,19]. By binding to specific sodium channel proteins, pyrethroids slow down the closing and opening of these channels, which causes the nervous system to become hyper-excited due to the increased amount of sodium entering the channels [18,20,21].…”

“…By binding to specific sodium channel proteins, pyrethroids slow down the closing and opening of these channels, which causes the nervous system to become hyper-excited due to the increased amount of sodium entering the channels [18,20,21]. Gamma aminobutyric acid (GABA)-gated chloride channels and calcium channels have been implicated as additional sites of action [22].…”

“…The main mechanism of action of Type I pyrethroids (such as permethrin) is primarily axonal sodium channel depolarization causing repetitive nerve impulses [22]. Type II pyrethroids work by depolarizing the cell membrane [18,19,22,23]. Evidence suggests that the mechanism of action differs in toxicity of type I and type II pyrethroids [22,24].…”

“…In humans, dermal exposure to permethrin can cause irritation, itching, and paresthesia, while ingestion may cause nausea, vomiting, sore throat, abdominal pain, coma, convulsions and death [25][26][27]. Studies have shown that dermal exposure of permethrin has caused irritation in rabbits, and ingestion of the product has caused transient signs in dogs, including tremors [18,28]. Permethrin is highly toxic to cats and the toxicity often occurs following exposure to a highly concentrated (45-65%) spoton permethrin product designed for canines, either by direct application, grooming, or being in close contact with recently treated dogs [18,29].…”

“…Studies have shown that dermal exposure of permethrin has caused irritation in rabbits, and ingestion of the product has caused transient signs in dogs, including tremors [18,28]. Permethrin is highly toxic to cats and the toxicity often occurs following exposure to a highly concentrated (45-65%) spoton permethrin product designed for canines, either by direct application, grooming, or being in close contact with recently treated dogs [18,29]. Clinical signs may include tremors, muscle fasciculations, twitches, seizures, ataxia, mydriasis, temporary blindness, and death [30].…”