How long does a tick injection remain effective after a dog is bitten? - briefly
A tick medication typically stays effective for about 30 days after a dog has been bitten, though the exact period depends on the specific product used.
How long does a tick injection remain effective after a dog is bitten? - in detail
The effectiveness of a tick‑preventive injection depends on the active ingredient, the formulation approved for canine use, and the timing of administration relative to the bite.
Injectable products such as moxidectin‑based solutions (e.g., ProHeart 6) achieve therapeutic blood levels within 24 hours. Once peak concentrations are reached, they maintain concentrations sufficient to kill or impair attached ticks for the labeled interval, typically 30 to 60 days. For a single dose administered after a bite, the drug begins to affect the tick within a few hours, but full efficacy is realized only after the systemic level stabilizes, usually after one day.
Key factors influencing the duration of protection:
- Product label – most injectable tick preventatives are marketed for a 4‑week or 8‑week protection period; the label specifies the maximum interval between doses.
- Dosage relative to body weight – under‑dosing shortens the active window, while correct dosing sustains the expected duration.
- Tick species – some species (e.g., Ixodes spp.) are more susceptible to the drug than others; resistance can reduce the effective period.
- Time of bite – if the injection is given after the tick has attached for several days, the parasite may have already transmitted pathogens; the injection will not reverse that risk.
- Metabolic rate – younger or highly active dogs may clear the drug faster, marginally decreasing the protective window.
In practice, a veterinarian will advise re‑administration at the end of the labeled interval to ensure continuous protection. If a bite occurs near the end of the dosing cycle, an additional injection may be recommended to restore systemic levels promptly. Monitoring for signs of tick‑borne disease remains essential, as the injection does not guarantee 100 % prevention of pathogen transmission once a tick has been attached.