How long does the Nexgard medication for ticks work in dogs? - briefly
A single NexGard chew protects dogs from ticks for approximately one month. Efficacy typically lasts up to 30 days after administration.
How long does the Nexgard medication for ticks work in dogs? - in detail
NexGard is an oral chewable tablet that delivers afoxolaner, an insecticide that targets the nervous system of ticks. After ingestion, the compound is absorbed rapidly, reaching peak plasma concentrations within 2–4 hours. Effective concentrations persist in the bloodstream, providing continuous protection against attached ticks for a full month.
The product label guarantees ≥ 90 % efficacy against common tick species for 30 days following a single dose. Field studies report average kill times of 12 hours for adult ticks and 24 hours for nymphs, with larvae eliminated within 48 hours. Because afoxolaner does not accumulate in tissues, the protective window ends when plasma levels fall below the therapeutic threshold, typically at the end of the 4‑week interval.
Factors that may influence the duration of activity include:
- Body weight: dosage is calibrated to weight bands; under‑dosing can shorten the effective period.
- Breed metabolism: rapid hepatic clearance in some breeds may reduce plasma concentration slightly, though clinical impact is minimal.
- Concurrent medications: agents that induce cytochrome P450 enzymes could accelerate afoxolaner elimination.
To maintain uninterrupted tick control, the tablet should be administered once every 30 days, regardless of the dog's age after eight weeks and a minimum weight of 4 lb (1.8 kg). Missed doses should be given as soon as possible; the next dose must follow the regular 30‑day schedule, not the interval since the missed administration.
In summary, a single oral dose of NexGard provides continuous tick protection for approximately one month, with rapid onset and sustained activity that meets or exceeds the 90 % efficacy benchmark throughout that period. Regular monthly dosing is essential to prevent gaps in coverage.