How many drops are absorbed from flea medication? - briefly
Only a small fraction of the applied solution enters the animal’s bloodstream—typically less than 0.1 mL, which corresponds to about two to three drops per dose.
How many drops are absorbed from flea medication? - in detail
Topical flea treatments for dogs and cats are applied as a specific number of drops to a defined area of skin, usually the back of the neck or along the spine. The actual volume that penetrates the epidermis and enters the bloodstream varies with formulation, species, body weight, and coat condition.
The applied dose is calculated in milliliters; one milliliter equals 20 drops when using a standard dropper. For an average adult dog weighing 20 kg, a common product recommends 1 ml (≈20 drops) applied to the skin. Approximately 10‑15 % of that volume is absorbed systemically within the first hour, reaching peak plasma concentration after 4‑6 hours. The remaining liquid spreads across the skin surface, binds to hair follicles, and is eliminated through normal grooming and shedding.
Key factors that influence the proportion of drops taken up by the animal include:
- Active ingredient concentration – higher percentages of imidacloprid, selamectin, or fipronil increase the gradient for transdermal diffusion.
- Skin integrity – lesions, excessive oil, or thick coats reduce absorption; a clean, dry surface enhances it.
- Temperature – warmer skin raises permeability, potentially increasing uptake by up to 5 % compared to cooler conditions.
- Species differences – cats generally absorb a slightly lower fraction than dogs due to differences in skin thickness and metabolic pathways.
Safety guidelines advise applying the exact number of drops specified on the product label; exceeding the dose does not proportionally increase efficacy but may raise the risk of systemic toxicity. Veterinarians often calculate the required volume based on the animal’s weight, ensuring that the absorbed amount stays within the therapeutic window established during clinical trials.
In summary, a standard application of 20 drops delivers roughly 0.2 ml of medication, of which 10‑15 % enters the bloodstream within the first few hours. Adjustments to the drop count are unnecessary unless the product label dictates a different dosage for the specific weight class or species.