title: Comparative speed of kill of sarolaner (Simparica) and afoxolaner (NexGard) against induced infestations of Ctenocephalides felis on dogs.
abstract: BACKGROUND
  Fleas are the most common ectoparasite infesting dogs globally. The many possible sequellae of infestation include: direct discomfort; allergic reactions; and the transmission of pathogens. Rapid speed of kill is an important characteristic for a parasiticide in order to alleviate the direct deleterious effects of fleas, reduce the impact of allergic responses, and break the flea infestation cycle. In this study, the speed of kill of a novel orally administered isoxazoline parasiticide, sarolaner (Simparica) against fleas on dogs was evaluated and compared with afoxolaner (NexGard) for 5 weeks after a single oral dose.
  
  
  METHODS
  Twenty-four dogs were randomly allocated to treatment with a single oral dose at label rate of either sarolaner (2 to 4 mg/kg) or afoxolaner (2.5 to 6.8 mg/kg) or placebo, based on pretreatment flea counts. Dogs were combed and live fleas counted at 8, 12 and 24 h after treatment and subsequent re-infestations on Days 7, 14, 21, 28 and 35. Efficacy was determined at each time point relative to counts for placebo dogs.
  
  
  RESULTS
  There were no adverse reactions to treatment. A single oral dose of sarolaner provided ≥98.8% efficacy (based on geometric means) within 8 h of treatment or subsequent weekly re-infestations of fleas to Day 35. By 12 h, fleas were virtually eradicated from all dogs, with only two fleas recovered from a single sarolaner-treated dog on Day 7; efficacy was 100% at all other time points. Significantly greater numbers of live fleas were recovered from afoxolaner-treated dogs at 8 h on all days and at 12 h on Days 28 and 35 (P < 0.05).
  
  
  CONCLUSIONS
  In this controlled laboratory evaluation, sarolaner had a significantly faster speed of kill against fleas than afoxolaner. This was noticeably more evident towards the end of the treatment period. The rapid and consistent kill of fleas within 8 to 12 h after a single oral dose of sarolaner over 35 days indicates that this treatment will provide highly effective control of flea infestations, relief for dogs afflicted with flea allergy dermatitis, and should reduce the risk of flea-borne pathogen transmission.
authors.affiliation: Zoetis, Veterinary Medicine Research and Development, 333 Portage St., Kalamazoo, MI, 49007, USA. robert.six@Zoetis.com.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Six
authors.affiliation: ClinVet International (pty) Ltd, Uitsigweg, Bainsvlei, 9338, Bloemfontein, Republic of South Africa. julian.liebenberg@clinvet.com.
authors.forename: Julian
authors.initials: J
authors.lastname: Liebenberg
authors.affiliation: Zoetis, Veterinary Medicine Research and Development, 333 Portage St., Kalamazoo, MI, 49007, USA. nicole.a.honsberger@zoetis.com.
authors.forename: Nicole A
authors.initials: NA
authors.lastname: Honsberger
authors.affiliation: Zoetis, Veterinary Medicine Research and Development, 333 Portage St., Kalamazoo, MI, 49007, USA. sean.mahabir@zoetis.com.
authors.forename: Sean P
authors.initials: SP
authors.lastname: Mahabir
mesh_terms: D000284:Administration, Oral; D000818:Animals; D058251:Ctenocephalides / Q000187:drug effects* / Q000502:physiology*; D004283:Dog Diseases / Q000188:drug therapy* / Q000469:parasitology; D004285:Dogs; D058267:Flea Infestations / Q000188:drug therapy / Q000662:veterinary*; D007306:Insecticides / Q000008:administration & dosage*; D007555:Isoxazoles / Q000008:administration & dosage*; D059208:Parasite Load; D010919:Placebos / Q000008:administration & dosage; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D007306:Insecticides; D007555:Isoxazoles; D010919:Placebos