How do flea drops work on dogs? - briefly
Flea drops are topical formulations that deliver insecticidal compounds through the skin into the dog’s bloodstream, where they eliminate feeding fleas. The product spreads across the coat, offering several weeks of protection.
How do flea drops work on dogs? - in detail
Flea spot‑on products for canines contain systemic insecticides that are absorbed through the skin after a single application to the mid‑neck area. The active molecules—commonly imidacloprid, fipronil, selamectin, fluralaner, or a combination—penetrate the epidermis within minutes, enter the bloodstream, and circulate to the skin surface via sebum and hair follicles.
Once in the peripheral tissues, the compounds bind to specific receptors of the insect nervous system. Imidacloprid acts as a nicotinic acetylcholine agonist, causing continuous nerve stimulation and paralysis. Fipronil blocks GABA‑gated chloride channels, leading to uncontrolled neuronal firing. Selamectin opens glutamate‑gated chloride channels, while fluralaner inhibits GABA‑ and glutamate‑gated receptors. In each case, the result is rapid immobilization and death of adult fleas, larvae, and, for some formulations, ticks and mites that feed on the host’s blood.
Efficacy depends on several variables:
- Proper placement of the dose on a shaved or thin‑haired region ensures maximal absorption.
- Body weight determines the volume of product; manufacturers provide dosage charts to maintain therapeutic concentration.
- Hair length and condition affect distribution; extensive grooming or bathing within 24–48 hours can reduce effectiveness.
- Environmental temperature influences skin perfusion; colder conditions may slow systemic uptake.
Typical protection periods range from one month (imidacloprid‑based) to twelve weeks (fluralaner‑based). Continuous exposure maintains lethal levels in the host’s skin and blood, preventing reinfestation after each flea bite.
Safety profile is established through extensive toxicology testing. Systemic absorption limits oral exposure, and the compounds exhibit low toxicity to mammals at recommended doses. Nevertheless, caution is advised for:
- Pregnant or lactating dogs, where certain ingredients may cross the placental barrier.
- Animals with compromised skin integrity, which could allow excessive systemic uptake.
- Concurrent use of other ectoparasitic products containing overlapping active ingredients, risking additive toxicity.
Resistance management involves rotating between products with different modes of action and adhering to label‑specified treatment intervals. Monitoring for reduced efficacy should prompt veterinary consultation and possible adjustment of the control regimen.