VetMedFlea & tick prevention in cats: does monthly selamectin + sarolaner reduce flea and tick counts in field and laboratory studies? — LIKELY
In cats, does monthly topical selamectin plus sarolaner (Stronghold Plus / Revolution Plus) prevent flea and tick infestations — in European field conditions and in laboratory challenge?
Shelf #61 · gate-verified and displayed under the developer's blinded-trial rule
LIKELY: In two randomised, blinded European field studies, three monthly doses of selamectin plus sarolaner held flea efficacy at 97.4%, 97.3%, 98.8% and 99.4% on days 14, 30, 60 and 90 (non-inferior to imidacloprid/moxidectin at every time-point; 277 cats in the flea study) and overall tick efficacy at 96.7%, 92.6%, 98.8% and 99.5% (non-inferior to fipronil at every time-point and superior on days 30 and 60; 200 cats in the tick study). Placebo-controlled laboratory studies agree: in the blinded flea studies (Becskei 2017), one dose killed fleas at 100% for 5 weeks in one study and at 97.7–100% after re-infestation in another, and in the tick programme (placebo-controlled, randomly allocated, blinding not stated), a single dose held efficacy at 97.2% or higher against Ixodes species (I. ricinus / I. hexagonus) for at least 5 weeks, at 95.8% or higher against R. sanguineus for at least 4 weeks (100% against existing infestations), and at 94.4% or higher against D. reticulatus for at least 4 weeks — an across-species floor of 94.4%. Design class (a): randomisation and blinding are both established by carded records (Geurden 2017 field studies, randomised and blinded; Becskei 2017, placebo-controlled and blinded). The honest limits: field trials compare against active products, not placebo, and nearly all of this programme is the manufacturer's — the consistency across field and laboratory designs is what carries LIKELY. Drafted Nov 10, 2026 (VetMed build, topic #61); all figures from abstracts fetched and verified at drafting.
Geurden 2017: in 277 cats in the flea study, selamectin/sarolaner flea efficacy was 97.3–99.4% on days 14–90 and non-inferior to imidacloprid/moxidectin; in 200 cats in the tick study, tick efficacy was 92.6–99.5% and superior to fipronil on days 30 and 60
Randomised, blinded, multi-centre field studies (two) — record's own wording: 'Two randomised, blinded, multi-centre field studies'; publication types include Randomized Controlled Trial
Who: Cats: cats presented as veterinary patients in Europe (Germany, Italy, France, Hungary) with natural flea or tick infestations, enrolled 2:1 (selamectin/sarolaner : comparator) and treated on days 0, 30 and 60 with spot-on selamectin plus sarolaner at 6.0–12.0 mg selamectin and 1.0–2.0 mg sarolaner per kg. Flea study: 277 cats assessed for efficacy and safety (a further 170 for safety only), comparator imidacloprid plus moxidectin; 16 cats had flea allergy dermatitis (FAD) at enrolment. Tick study: 200 cats assessed for efficacy and safety (a further 70 for safety only), comparator fipronil; four tick species identified.
Result: Flea efficacy in the selamectin/sarolaner group was 97.4%, 97.3%, 98.8% and 99.4% on days 14, 30, 60 and 90, versus 90.0%, 83.6%, 87.7% and 96.3% for imidacloprid/moxidectin; selamectin/sarolaner was non-inferior at all time-points, and clinical signs improved in the 16 cats with FAD. Overall tick efficacy was 96.7%, 92.6%, 98.8% and 99.5% versus 90.2%, 74.6%, 83.0% and 93.4% for fipronil; selamectin/sarolaner was non-inferior at all time-points and superior on days 30 and 60. There were no serious treatment-related adverse events in any study.
Watch out: Both comparators are active licensed products, not placebo — field prevention trials are built this way — and efficacy is calculated as percent reduction from each cat's own pre-treatment count, not as parasite-free proportions. This is the manufacturer's (Zoetis) development programme; the FAD finding rests on 16 cats.
Geurden T, Becskei C, Farkas R, Lin D, Rugg D. Efficacy and safety of a new spot-on formulation of selamectin plus sarolaner in the treatment of naturally occurring flea and tick infestations in cats presented as veterinary patients in Europe. Veterinary parasitology. 2017;238 Suppl 1:S12-S17. PMID: 28395750. Registry ID: none in the record. MeSH: Administration, Topical · Animals · Antiparasitic Agents/administration & dosage · Cat Diseases/drug therapy · Cats · Europe · Female · Flea Infestations/drug therapy · Flea Infestations/veterinary · Imidazoles/administration & dosage · Isoxazoles/administration & dosage · Ivermectin/administration & dosage · Ivermectin/analogs & derivatives · Macrolides/administration & dosage · Male · Neonicotinoids · Nitro Compounds/administration & dosage · Pyrazoles/administration & dosage · Tick Infestations/drug therapy · Tick Infestations/veterinary · Treatment Outcome
Becskei 2017: one selamectin/sarolaner dose gave 100% flea efficacy for 5 weeks in one blinded placebo-controlled study of cats, and 97.7–100% after weekly re-infestation in a second
Three placebo-controlled, blinded laboratory studies (record's own wording: 'three placebo-controlled, blinded studies'); cats randomly allocated after blocking by pre-treatment flea counts
Who: Cats: purpose-bred adult cats (n = 8 per group), blocked by pre-treatment flea counts and randomly allocated to placebo or to spot-on selamectin plus sarolaner at the minimum dose of 6.0 mg selamectin and 1.0 mg sarolaner per kg, applied once on day 0. All cats were infested with approximately 100 unfed adult Ctenocephalides felis before treatment and at weekly intervals for 5 weeks; comb counts at 24 hours (studies 1 and 2) or at timed intervals for speed of kill (study 3).
Result: Placebo-treated cats maintained flea infestations throughout all studies. In study 1, no live fleas were found on any treated cat — 100% efficacy for 5 weeks after a single treatment (P ≤ 0.0001). In study 2, selamectin/sarolaner reduced flea counts by 92.4% immediately after treatment and by 97.7%–100% after re-infestations for five weeks (P ≤ 0.0001). In the speed-of-kill study, killing started within 12 hours after treatment and within 6 hours after re-infestation for at least 28 days; efficacy was 98.1% by 24 hours after treatment and 100% within 24 hours after re-infestations for 5 weeks.
Watch out: The shorthand '100% flea kill in all three studies' overstates two of them: study 2 was 92.4% immediately after treatment and study 3 was 98.1% at 24 hours, reaching 100% only after re-infestations. These are small groups (8 per group) of purpose-bred cats under induced infestation — precision comes from the field studies, not from these.
Becskei C, Cherni JA, Vatta AF, King VL, Lin D, Rugg D. Efficacy and speed of kill of a new spot-on formulation of selamectin plus sarolaner against flea infestations in cats. Veterinary parasitology. 2017;238 Suppl 1:S18-S21. PMID: 28395751. Registry ID: none in the record. MeSH: Administration, Topical · Animals · Antiparasitic Agents/administration & dosage · Cat Diseases/drug therapy · Cats · Female · Flea Infestations/drug therapy · Flea Infestations/veterinary · Isoxazoles/administration & dosage · Ivermectin/administration & dosage · Ivermectin/analogs & derivatives · Male · Random Allocation · Time Factors · Treatment Outcome
Geurden 2017 (tick laboratory studies): a single selamectin/sarolaner dose in cats was at least 97.2% effective against existing Ixodes infestations and at least 94.4% against Dermacentor reticulatus for at least 4 weeks across seven studies
Seven laboratory studies — cats randomly allocated, placebo-controlled (record states random allocation and placebo treatment; blinding not stated in the record)
Who: Cats: 16 adult purpose-bred cats in each of seven laboratory studies, randomly allocated to one of two treatment groups based on pre-treatment tick counts and treated on day 0 with selamectin plus sarolaner at the minimum label dose (6.0 mg selamectin and 1.0 mg sarolaner per kg) or with placebo. Weekly infestations with 50 unfed adult ticks: Ixodes ricinus (2 studies), Ixodes hexagonus (1 study), Dermacentor reticulatus (2 studies) or Rhipicephalus sanguineus (2 studies); ticks counted 48 hours after treatment and after each re-infestation.
Result: Geometric mean live tick counts were significantly lower in the selamectin/sarolaner group than the placebo group at all time-points (P ≤ 0.0012). Against I. ricinus and I. hexagonus, efficacy was 97.2% or higher against existing infestations and 97.4% or higher against weekly re-infestations for at least 5 weeks. Treatment was 100% effective against existing R. sanguineus infestations and 95.8% or higher for at least 4 weeks, and gave 94.4% or higher efficacy against D. reticulatus for at least 4 weeks. No treatment-related adverse reactions were recorded in any study.
Watch out: Blinding is not stated in this record (the companion flea laboratory studies were blinded; this one is carded on what its own record says). Induced infestations of purpose-bred cats at the minimum dose — the result supports the monthly label interval, not longer gaps between doses.
Geurden T, Becskei C, Vatta AF, Slootmans N, von Reitzenstein M, King VL, Lin D, Rugg D. Efficacy of a new spot-on formulation of selamectin plus sarolaner against four common tick species infesting cats in Europe. Veterinary parasitology. 2017;238 Suppl 1:S3-S7. PMID: 28395754. Registry ID: none in the record. MeSH: Acaricides/administration & dosage · Administration, Topical · Animals · Cat Diseases/drug therapy · Cats · Europe · Female · Isoxazoles/administration & dosage · Ivermectin/administration & dosage · Ivermectin/analogs & derivatives · Male · Random Allocation · Tick Control/standards · Tick Infestations/drug therapy · Tick Infestations/veterinary · Ticks · Time Factors · Treatment Outcome
Synthesis: monthly selamectin plus sarolaner reduces flea and tick counts throughout the dosing interval — LIKELY
Synthesis
Who: Synthesis of the cards above: Geurden 2017 field studies (277 cats, flea study; 200 cats, tick study; randomised and blinded, active comparators), Becskei 2017 (three placebo-controlled blinded laboratory flea studies in cats) and Geurden 2017 tick laboratory programme (seven placebo-controlled studies in cats, four European tick species).
Result: (1) Field fleas: 97.3–99.4% efficacy across days 14–90 over three monthly doses, non-inferior to imidacloprid/moxidectin, with FAD signs improving. (2) Field ticks: 92.6–99.5% efficacy, non-inferior to fipronil throughout and superior on days 30 and 60. (3) Laboratory fleas: a single minimum dose reached 100% efficacy in one study and 97.7–100% after weekly re-infestation in another, with kill starting within 6–12 hours. (4) Laboratory ticks: 94.4% or higher efficacy for at least 4 weeks against all four common European species. Field and laboratory evidence point the same way within one manufacturer's (Zoetis) programme — randomised, blinded designs with large, consistent effects across field and laboratory settings support LIKELY, and that single-programme basis is why the stamp is LIKELY and not PROBABLE.
Watch out: This shelf is about the selamectin/sarolaner combination only; it does not rank it against other feline preventives, and it says nothing about tick-borne disease prevention, which depends on speed of kill relative to pathogen transmission and is a separate question. Distinct from Shelf #7 (flea and tick prevention in dogs) and Shelf #29 (heartworm prevention in cats — the McTier selamectin records are heartworm records and are not carded here).
Synthesis of Geurden T et al. PMID: 28395750; Becskei C et al. PMID: 28395751; Geurden T et al. PMID: 28395754. Registry IDs as on the individual cards.
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