How do the major flea and tick preventive classes compare in efficacy and safety in dogs?

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The isoxazoline class (fluralaner, sarolaner, lotilaner, afoxolaner) delivers the highest and most consistent flea and tick efficacy in dogs, with mean reductions exceeding 97% sustained across full label intervals. The imidacloprid/flumethrin collar (Seresto) provides comparable long-term control over 7–8 months, while topical fipronil-based products are effective but show greater variability, particularly against ticks. --- Oral Isoxazolines Fluralaner (Bravecto) oral chew achieves flea-control efficacy of 99.2%, 99.8%, 99.8%, and 99.9% at weeks 2, 4, 8, and 12 from a single dose, compared to 94.1%, 93.0%, 96.0%, and 97.3% for topical fipronil over the same period.1 Tick-control efficacy for fluralaner was 99.9%, 99.9%, 99.7%, and 100% at those same time points.1 Of dogs with flea allergy dermatitis (FAD) at enrollment, 85.7% in the fluralaner group showed no clinical FAD signs through study completion, versus 55.6% in the fipronil group.1 Injectable fluralaner (Bravecto injectable, 15 mg/kg SC) provides year-long flea and tick control equivalent to 12 monthly afoxolaner doses. From visits 2 through 10, ≥95% of fluralaner-treated dogs were tick-free and ≥93% were flea-free; tick and flea counts were reduced by >99% from baseline.6 Afoxolaner achieved >98% tick reduction and >97% flea reduction over the same period, with non-inferiority confirmed at all visits.6 No unexpected adverse events occurred in either group, and no interactions with concomitantly administered vaccines or medications were observed.6 Topical fluralaner controls fleas for 12 weeks from a single application. Flea-count reductions at weeks 4, 8, and 12 met the ≥90% efficacy threshold required for the study endpoint.14 Sarolaner (Simparica, minimum 2.0 mg/kg PO q30d) achieves flea efficacy of 98.8%, 99.4%, >99.9%, and >99.9% on days 14, 30, 60, and 90, and tick efficacy of 97.4%, 97.6%, 99.8%, and 100% at those same time points.3 Sarolaner was superior to fipronil spot-on for tick control on day