Efficacy of Spinosad Tablets Administered to a Colony of 15 Indoor Cats Naturally Infested with Fleas

The aims of the study were (i) to describe adult fleas distribution in a strictly indoor cat colony composed of cats with flea allergy dermatitis (FAD) and non-FAD cats and (ii) to evaluate the efficacy of spinosad used alone. Skin lesions were scored according to the SCORing Feline Allergic Dermatitis lesion severity scale (SCORFAD) on days 0, 15, 30, 45, 60, and 90. Cats were combed prior to the treatment (days 0, 30, and 60) and on days 15, 45, and 90; collected fleas were replaced on the animals. All cats received flavored spinosad tablets (Comfortis) at a dosage of 50–75？mg/kg on days 0, 30, and 60. Cats were fed immediately afterwards. On day 0, a total of 60 fleas were collected (mean: ). Cats with FAD had a SCORFAD of 6, 8, 12, and 13 and harbored 0, 2, 1, and 0 fleas, respectively. Tablets were taken voluntarily by 8, 11, and 12 cats on days 0, 30, and 60, respectively. No adverse event was recorded. From day 15 to day 90, no fleas could be collected. SCORFAD was reduced by 40%, 71%, 80%, 89%, and 98% on days 15, 30, 45, 60, and 90, respectively. 1. Introduction Fleas remain the most common parasites in cats [1–4]. In addition to potentially carry zoonotic diseases [5], fleas cause skin irritations due to their bites, including in some animals an allergic dermatitis (the so-called flea allergic dermatitis or FAD) [6, 7]. FAD is the most common allergic skin disease of dogs and cats, although its frequency varies according to geographical location. The past twenty years have brought important advances in flea biology as well as better insecticides [8]. Nevertheless, flea control in general, and more specifically in cats with FAD, remains a real challenge for veterinarians and owners. The goal is to minimize flea bites, that is, to minimize the amount of saliva injected by fleas in order to be under the allergic threshold. Spinosad is an aerobic fermentation product of the soil bacterium, Saccharopolyspora spinosa. Spinosad kills insects through activation of the acetylcholine nervous system through nicotinic receptors. A chewable tablet is indicated for the treatment and prevention of flea infestations caused by Ctenocephalides felis; it was first introduced for dogs to the USA market in 2007 after approval by the Food and Drug Administration. The European Commission granted a marketing authorisation valid throughout the European Union in 2011 after approval by the European Medicines Agency. Subsequently, it was approved for cats in USA, Canada, and Japan in 2012 and in the European Union in 2013. Its excellent efficacy against fleas and its