How long do Barss flea drops for cats work? - briefly
Barss flea drops provide continuous protection for approximately 30 days after a single application. Re‑application is required each month to maintain efficacy.
How long do Barss flea drops for cats work? - in detail
Barss flea drops for cats provide systemic protection that begins within a few hours after application and persists for approximately four weeks. The product contains a single dose of fipronil, which spreads across the skin and is absorbed into the bloodstream, targeting fleas that feed on the animal.
- Onset of activity: 4–6 hours for adult fleas; 24 hours for eggs and larvae.
- Duration of efficacy: 30 days under normal conditions; efficacy may decline after 28 days if the cat is frequently bathed, swims, or is heavily groomed.
- Weight‑based dosing: Each pipette is calibrated for cats weighing 2.5–5 kg; larger cats require a higher‑volume dose to maintain the 30‑day protection window.
- Environmental influence: High humidity and temperature accelerate fipronil degradation on the skin surface, potentially shortening the residual period by 2–3 days.
- Resistance considerations: Flea populations with documented fipronil resistance may show reduced mortality; in such cases, efficacy may fall below 80 % after the first two weeks.
Reapplication should occur on the same calendar date each month to sustain uninterrupted control. If a cat experiences excessive bathing or exposure to water, a supplemental dose may be administered after 21 days, provided the total monthly limit is not exceeded. Monitoring for flea presence after the third week can confirm whether the protective window remains intact.