How does a flea tablet work in dogs? - briefly
Flea tablets for dogs typically contain active ingredients such as spinosad or nitenpyram that target and kill fleas at various stages of their life cycle. Once ingested by the dog, these compounds are absorbed into the bloodstream, which then passes through the flea when it feeds on the dog's blood, effectively killing the parasite.
How does a flea tablet work in dogs? - in detail
Flea tablets, also known as oral flea preventatives or systemic insecticides, are highly effective tools for controlling and preventing flea infestations in dogs. The active ingredients in these tablets typically belong to a class of compounds called isoxazolines, which include fluralaner (Bravecto), sarolaner (Simparica), and afoxolaner (NexGard). Understanding how these tablets work involves examining their mechanism of action and the pharmacokinetics involved.
When a flea tablet is administered to a dog, it is rapidly absorbed into the bloodstream through the gastrointestinal tract. The active ingredient then distributes throughout the body, including the skin and hair follicles where fleas are most likely to feed. Fleas ingest this substance when they bite the dog, as the blood meal contains a small amount of the active ingredient.
The primary mode of action for these isoxazolines involves targeting the nervous system of the flea. Specifically, they act on GABA-gated chloride channels and glutamate-gated chloride channels in the flea's nerve cells. By binding to these receptors, the active ingredient blocks the normal flow of chloride ions through the channels, leading to a state of hyperpolarization. This prevents the transmission of signals between neurons, causing uncontrolled activity and eventually paralysis and death of the flea.
The potent effect of these tablets on fleas is due to their high selectivity for insects compared to mammals. While dogs may experience minor side effects such as gastrointestinal upset or transient ataxia (loss of balance), the active ingredients have a much higher affinity for insect receptors, making them safer for use in pets than traditional topical treatments.
Another important aspect of flea tablets is their long-lasting efficacy. Depending on the specific product, these tablets can provide continuous protection against fleas for up to 12 weeks. This prolonged effect is achieved through the slow release and sustained distribution of the active ingredient in the dog's body. As the substance is gradually metabolized and excreted, new fleas that attempt to feed on the dog are exposed to a lethal dose, ensuring ongoing protection.
In summary, flea tablets work by administering an active ingredient that is absorbed into the dog's bloodstream and subsequently ingested by feeding fleas. The active ingredient targets the nervous system of the flea, leading to paralysis and death. This mechanism, combined with the selectivity for insect receptors and long-lasting efficacy, makes flea tablets a highly effective and safe choice for controlling and preventing flea infestations in dogs.