In primary care veterinary practice, flea and tick control is an essential component of the preventive healthcare strategy for cats. This is because of the high prevalence of flea infestation, the year-round risk of ticks, the risk of flea allergy dermatitis (FAD), the pathogens that fleas and ticks vector, and the introduction of fleas into the home.1,2
Fleas, particularly Ctenocephalides felis felis, are very common and perhaps the most clinically important ectoparasite of cats and dogs worldwide.3–5 Flea-related diseases could account for more than half of dermatologic cases presented to companion animal veterinarians.5–7 Results of European studies confirm that levels of feline flea infestation are variable, and can exceed 70% in an untreated population.6 A study of free-roaming cats in the central U.S. in 2014 found fleas on 71.6% and ticks on 18.7% of trapped cats.8 A multi-center study conducted at veterinary facilities in nine European countries evaluated 1519 client-owned cats untreated with ectoparasiticides in the preceding month9 found an overall 15.5% flea infestation prevalence. A flea infestation prevalence of 22.9% was reported in feline patients at 13 veterinary practices in Hungary,10 and a 21.1% prevalence at 31 practices in the U.K.11 In both the Hungarian and U.K. studies, the flea infestation prevalence in cats was considerably greater than the prevalence in dogs evaluated concurrently at the same sites. Moreover, in the U.K. study the prevalence of FAD lesions in cats (8.02%) was significantly greater (P < 0.001) than in dogs (6.82%). Approximately half of the pet owners in the U.K. study whose pets harbored fleas were unaware that their animals were infested. Other investigators confirm that asymptomatic cats can harbor low levels of flea infestation, in some cases the lack of flea awareness is apparently a result of overgrooming by the cat.12 Feral cats, untreated rural cats and indoor-outdoor cats may have considerably higher rates of infestation than indoor cats associated with their increased outdoor exposure to fleas.3,10
Fleas and ticks also carry and transmit an assortment of vector-borne pathogens that can affect cats and people, including Bartonella spp., Ehrlichia spp., Rickettsia spp., Mycoplasma spp., as well as cestode, protozoal, and filarial endoparasites.1,2,4,13,14 Investigators have found that as many as 80% of fleas collected from cat populations harbor feline or human pathogens of significance.15
Safe and effective feline flea and tick treatment options are therefore an important component of the companion animal armamentarium. The isoxazoline class of parasiticide compounds were introduced in 2013 for use in dogs and 2 years later for use in cats. Fluralaner (Bravecto®, Merck & Co., Inc.,Madison, NJ, USA) is a long-acting isoxazoline class molecule available in oral and topical formulations for use in dogs and in a topical formulation for use on cats, and is indicated for 12 week control of fleas and up to 12 weeks against a variety of tick species.16− 21 A recent field study found that a single topical dose of fluralaner reduced flea populations on household cats by 96.6% within seven days and by 100% at 12 weeks after treatment.13
Fluralaner kills newly emerging adult fleas on the host before they start laying eggs, which in untreated animals would fall off the host into the environment and develop into flea larvae and pupae. Interrupting on-animal egg production disrupts the flea life cycle, depleting the flea population in the home surroundings and preventing subsequent re-infestation of the host.22 Fluralaner has demonstrated onset of flea adulticidal activity within 2 hours after topical administration.16 As home environment studies have indicated,13,23 a rapid speed of kill and long duration of action prevent re-infestation of the host and home environment by eliminating all flea life stages from the environment.
In an effort to sample the veterinarian recommendations for flea and tick prevention in dogs, approximately 30 veterinarians in each of the US, UK and Australia were surveyed as part of a larger pet owner survey.24 For dogs, veterinarians recommended approximately 12 months of protection against fleas and 9–12 months protection against ticks per year. The Companion Animal Parasite Council recommends year-round ectoparasite control for dogs and cats. 25
Feline flea and tick control before the approval of fluralaner commonly involved ectoparasiticide administration to cats at monthly intervals. Weak owner adherence with recommended flea treatments may lead to a failure or delay in administering follow-on doses at the required time. This lack of adherence leads to persistence of the flea population in the household, and failure to follow recommended treatment recommendations is identified as the most common cause of flea treatment failure.26 Lack of treatment adherence is often followed by a perceived lack of efficacy and is a vital issue in clinical practice because it affects the owners confidence in the prescriber and medication as well as the actual treatment success.
One option for veterinary practitioners to potentially increase adherence to veterinary recommendations for flea and tick protection is through prescription of an extended duration product. This approach requires the cat owner to administer fewer doses over the same period of time. Prior studies across an array of drug classes in human and veterinary medicine have consistently shown an inverse relationship between treatment adherence and the complexity (particularly higher number of doses) and convenience of the therapeutic regimen.27
The objective of the study reported here was to compare the annual duration of flea and tick treatment purchased by cat owners in the United States who were prescribed the long duration treatment of fluralaner with the duration purchased by cat owners prescribed monthly ectoparasiticides.