As summer is approaching, dogs can develop more and more flea problems. Since such problems often occur in the home environment, there will be more requirements in the solutions for easy operation and low toxicity. To answer the call, pyrethroid insecticides can solve the problem.
Similar to pyrethrins extracted from natural pyrethrums, pyrethroids are essentially chemically stable forms of natural pyrethrums. With decades of research, pyrethroids developed from bioallethrin, tetramethrin, resmethrin, bioresmethrin to permethrin, cypermethrin, deltamethrin, etc. Different from natural pyrethrins, they are more resistant to degradation caused by light and air. That’s why pyrethroid insecticides are commonly used in agricultural, commercial and family environments.
Pyrethroid insecticides for home use are basically at low concentrations in case of any harm to humans. They work well for the control of a variety of pests including fleas on pets.
Mechanism of Action of Pyrethroid Insecticides
To kill pests, pyrethroid insecticides function by preventing the closure of the voltage-gated sodium channels in the axonal membranes. Sodium channel is a membrane protein with hydrophilic interior. This structure allows sodium ions to cross the membrane, enter the axon, and propagate an action potential. When the active ingredient of pyrethroid insecticides acts on a sodium channel, the nerve cannot repolarize, and the axonal membrane will be permanently depolarized. In this way, an insect will be paralyzed.
Among some types of pyrethroid insecticides, pyrethroids can also be used in combination with synergist piperonyl butoxide. Piperonyl butoxide is important for the metabolism of pyrethroid insecticides. The efficacy of pyrethroid insecticides can be multiplied with the addition.
Features of Pyrethroid Insecticides
Not all pyrethroid insecticides in the same category are equally effective for different pest species. However, most pyrethroid insecticides share the common features in the following:
- Low toxic to mammals and birds.
- Highly toxic to fish if used in water.
- Can kill insects with a low dose.
- Particularly effective for killing chewing insects. The dried remains of many pyrethroids can be well absorbed by pests.
- Can bind closely to soil particles and organic matters.
When used for flea control, pyrethroid insecticides, such as cypermethrin and deltamethrin, has a strong stomach toxicity. It will rapidly kill fleas within the environment. When used for killing fleas in the fur near the skin of a dog, pyrethroid insecticides are usually made in the form of water emulsion with low concentrations. They often needs to be further diluted according to instructions before actual use.
Application of Pyrethroid Insecticides
For flea infections in dogs, when using pyrethroid type water emulsions, users should carefully check the product label to determine the best application methods, e.g. shampooing or water immersion. After being applied onto the skin of a dog, ingredients will be distributed evenly, which can even be found in hair follicles, shed hair, and sebum.
Security and Applicability
Ingredients of pyrethroid insecticides can be absorbed through the skin, inhalation and ingestion. Pyrethroids do not bind to sodium channels in mammals and are difficult to absorb through the skin. They can also be metabolized by human liver efficiently. Therefore, pyrethroids are much less toxic to humans than they are to insects. Whether human exposure to small amounts of pyrethroid insecticides is harmful has not been exactly determined. What is certain is that a large dose of pyrethroids can also cause a toxic reaction, with itching and burning feeling, dizziness, nausea and muscle twitching.
It is important to note that pyrethroid insecticides often show completely different effects on dogs and cats. Pyrethroid insecticides can be used for pest control in dogs, including fleas, but not in cats. This is because cats’ livers metabolize pyrethroids through glucuronidation much less effectively than that of dogs. When pyrethroids are used onto a cat, it can be poisoned, with the symptoms of seizures, fever, ataxia, and even death.
