How do flea and tick drops work for cats? - briefly
The drops deliver neurotoxic agents that distribute over the cat’s skin and enter the bloodstream, killing fleas and ticks on contact. Absorption completes within hours, offering protection for up to a month.
How do flea and tick drops work for cats? - in detail
Flea‑and‑tick spot‑on products for felines are formulated as liquid solutions that are applied directly to the skin at the base of the neck. The active ingredients dissolve in the cat’s oil layer and spread across the surface of the skin through diffusion. This creates a protective zone that extends over the entire body as the animal grooms itself.
The process works in several stages:
- Absorption: The solvent (often alcohol or a light oil) carries the insecticidal compound into the epidermis within minutes.
- Distribution: Lipid‑soluble actives move through the sebaceous secretions, coating hair shafts and reaching the outermost skin layers.
- Contact toxicity: When a flea or tick lands on the treated fur, the chemical contacts its nervous system, binding to specific receptors (e.g., GABA‑gated chloride channels for fipronil, acetylcholinesterase for selamectin). This causes rapid paralysis and death.
- Systemic effect: Some ingredients are absorbed into the bloodstream, allowing the cat’s own circulation to deliver the toxin to feeding parasites, which ingest the compound while sucking blood and are subsequently eliminated.
- Residual activity: The formulation remains effective for weeks because the active molecules are stable in the lipid environment and are not easily washed off by bathing or normal grooming.
Safety is achieved by selecting doses that are lethal to arthropods but far below toxic thresholds for mammals. Manufacturers calculate the concentration based on the average body weight of domestic cats, and the product label specifies the maximum weight range for each dose.
Overall, the spot‑on method provides a rapid, long‑lasting barrier that exploits the biology of ectoparasites, delivering a lethal dose upon contact or ingestion while preserving the health of the host animal.