Genotyping USA laboratory-maintained isolates and European clinical isolates of Dirofilaria immitis to assess macrocyclic lactone susceptibility or resistance at predictive SNP sites using droplet digital PCR.

Dirofilaria immitis is a parasitic nematode that causes cardiovascular dirofilariosis ("heartworm disease") primarily in canids. The principal approach for mitigating heartworm infection involves the use of macrocyclic lactone (ML) for prophylaxis. Recent research has substantiated the emergence of D. immitis displaying resistance to MLs in the USA. Numerous factors, such as the mobility of companion animals and competent vectors could impact the spread of drug resistance. Genomic analysis has unveiled that isolates resistant to ML exhibit unique genetic profiles when compared to their wild-type (susceptible) counterparts. Out of the ten single nucleotide polymorphism (SNP) markers validated in clinical samples of D. immitis from the USA, four have demonstrated their effectiveness in distinguishing between isolates with varying ML efficacy phenotypes. This study explores the potential of these confirmed SNPs for conducting surveillance studies. Genotypic analysis using SNP markers emerges as a valuable tool for carrying out surveys and evaluating individual clinical isolates. Two USA laboratory-maintained isolates (Berkeley, WildCat) and twenty-five random European clinical samples of either adult worms or microfilariae (mf) pools isolated from domestic dogs, were tested by droplet digital PCR (ddPCR)-based duplex assay. This approach elucidates genetic evidence pertaining to the development of drug resistance and provides baseline data on resistance related genotypes in Europe. The data on these clinical samples suggests genotypes consistent with the continued efficacy of ML treatment regimens in Europe. In addition, this assay can be significant in discriminating cases of drug-resistance from those possibly due to non-compliance to the recommended preventive protocols.

Year-round efficacy of a single treatment of fluralaner injectable suspension (Bravecto QuantumTM) against repeated infestations with Ixodes holocyclus in dogs.

BACKGROUND: The longer the duration of protection of an acaricide against canine infestation with Ixodes holocyclus, the lower the risk of gaps in tick control programs that will place dogs at risk of potentially fatal tick-induced paralysis. Two studies investigated the duration of efficacy provided by a novel injectable suspension of fluralaner (Bravecto QuantumTM) against this tick species. METHODS: In both studies, 20 clinically healthy dogs were randomized to an untreated control group or to a group treated once, on Day 0, with the injectable fluralaner suspension (15 mg/kg). Dogs were infested with up to 25 unfed adult female I. holocyclus ticks on Day -1, during Weeks 1 and 2, and then at intervals no greater than approximately 3 months for the 13 months following treatment. Ticks were assessed in situ at 24 and 48 h and assessed and removed at 72 h following treatment and each subsequent infestation. Efficacy was determined by comparing arithmetic mean live tick (attached or free) counts in the treated group with the control group. RESULTS: The untreated control dogs maintained adequate infestations for efficacy evaluations at all assessment weeks, with mean tick counts ranging from 16.2 to 21.6 in Study 1 and 14.0 to 23.5 in Study 2. The efficacy of fluralaner injectable suspension against existing infestations, determined 72 h following treatment administration, was 64.1% in Study 1 and 42.7% in Study 2. Efficacy against post-treatment infestations in Study 1 ranged from 95.7 to 100% from Week 1 through Week 57; in Study 2 efficacy was 100% at every assessment from Week 1 through Week 57. No treatment-related adverse events were recorded in either study. CONCLUSION: The injectable fluralaner suspension was highly effective against I. holocyclus infestations of dogs from one week through 13 months following a single treatment. By placing treatment with the veterinarian, killing ticks within 72 h of attachment, and providing a full year of protection, fluralaner injectable suspension can help facilitate owner compliance with tick control treatment recommendations, thus reducing the risk of canine tick paralysis.

Year-round efficacy of a single treatment of fluralaner injectable suspension (Bravecto Quantum™) against repeated infestations with Rhipicephalus sanguineus (sensu lato) and Ctenocephalides felis in dogs.

BACKGROUND: Poor owner compliance with monthly control measures means that dogs in Australia can remain susceptible to infestations with fleas, present throughout the whole year, and brown dog ticks, which thrive in tropical and subtropical areas. A 150 mg/ml injectable fluralaner suspension (Bravecto Quantum™) was developed to help ensure year-round protection against these parasites. A study investigated the persistent efficacy of this formulation against repeated challenges with Rhipicephalus sanguineus (sensu lato) and Ctenocephalides felis throughout 12 months following a single subcutaneous treatment. METHODS: Twenty dogs were blocked by pre-treatment R. sanguineus s.l. counts and randomized to an untreated control group or to a group treated once, on day 0, with the fluralaner injection (15 mg/kg). Infestations of 50 mixed-sex, unfed adult R. sanguineus s.l. and up to 100 C. felis were done on days 7, 14, 35, 63, 91, 126, 154, 182, 210, 245, 273, 301, 336 and 365. Live flea and tick counts were completed 48 h post-infestation. Flea infestations were also done on day -1, with counts on day 2. Infestations were considered adequate if at each evaluation, at least six dogs in the control group retained at least 20% of tick challenges and 25% of flea challenges. RESULTS: The fluralaner injectable suspension was well tolerated. Efficacy against existing flea infestations was > 99% (arithmetic and geometric means) at 48 h post-treatment. At all subsequent assessments throughout the year following treatment, efficacy against fleas remained at 100%. Arithmetic mean tick count reductions relative to the control group ranged from 97.6% to 100% from day 7 through 11 months and was 92.6% at 12 months (geometric means 95.2% to 100% through 12 months). CONCLUSION: The injectable fluralaner suspension was effective against fleas and brown dog ticks for 12 months following a single treatment. Compared with more frequently administered products where compliance may be suboptimal, the year-round efficacy of this veterinarian-administered fluralaner formulation has the potential to improve owner compliance for control of fleas and ticks. In turn, by reducing the detrimental effects of flea and tick infestations and risk of transmission of flea- and tick-borne pathogens, canine health can be enhanced.

Fluralaner (Bravecto®) treatment kills Aedes aegypti after feeding on Dirofilaria immitis-infected dogs.

BACKGROUND: Transmission of canine heartworm (Dirofilaria immitis) from infected to naïve dogs is dependent on successful mosquito feeding and survival. METHODS: To determine whether treating heartworm-infected dogs with fluralaner (Bravecto®) limits the survival of infected mosquitoes, and potentially the transmission of D. immitis, we allowed female mosquitoes to feed on microfilaremic dogs and evaluated mosquito survival and infection with D. immitis. Eight dogs were experimentally infected with D. immitis. On day 0 (~ 11 months post-infection), four microfilaremic dogs were treated with fluralaner according to label directions while the other four were non-treated controls. Mosquitoes (Aedes aegypti Liverpool) were allowed to feed on each dog on days -7, 2, 30, 56, and 84. Fed mosquitoes were collected, and the number of live mosquitoes determined at 6 h, 24 h, 48 h, and 72 h post-feeding. Surviving mosquitoes held for 2 weeks were dissected to confirm third-stage D. immitis larvae; PCR (12S rRNA gene) was performed post-dissection to identify D. immitis in mosquitoes. RESULTS: Prior to treatment, 98.4%, 85.1%, 60.7%, and 40.3% of mosquitoes fed on microfilaremic dogs were alive at 6 h, 24 h, 48 h, and 72 h post-feeding, respectively. Similarly, mosquitoes fed on microfilaremic, non-treated dogs were alive 6 h post-feeding (98.5-100%) throughout the study. In contrast, mosquitoes fed on fluralaner-treated dogs 2 days after treatment were dead or severely moribund by 6 h post-feeding. At 30 and 56 days post-treatment, > 99% of mosquitoes fed on treated dogs were dead by 24 h. At 84 days post-treatment, 98.4% of mosquitoes fed on treated dogs were dead by 24 h. Before treatment, third-stage larvae of D. immitis were recovered from 15.5% of Ae. aegypti 2 weeks after feeding, and 72.4% were positive for D. immitis by PCR. Similarly, 17.7% of mosquitoes fed on non-treated dogs had D. immitis third-stage larvae 2 weeks after feeding, and 88.2% were positive by PCR. Five mosquitoes fed on fluralaner-treated dogs survived 2 weeks post-feeding, and 4/5 were from day 84. None had third-stage larvae at dissection, and all were PCR-negative. CONCLUSION: The data indicate that fluralaner treatment of dogs kills mosquitoes and thus would be expected to reduce transmission of heartworm in the surrounding community.

Treatment of dogs with Bravecto® (fluralaner) reduces mosquito survival and fecundity.

BACKGROUND: Mosquitoes serve as the vector of canine heartworm (Dirofilaria immitis), which represents a significant and persistent threat to canine health. A reduction in the longevity and/or reproductive success of mosquitoes that take a blood meal from fluralaner-treated dogs may consequently reduce the local transmission of heartworm and prevent new infections. A novel secondary effect of an oral formulation of the ectoparasiticide fluralaner (Bravecto®) against a laboratory strain of the mosquito Aedes aegypti, a potential major vector of canine heartworm, was investigated in this study. METHODS: Six dogs were administered a single dose of fluralaner orally in the form of Bravecto® Chews (at the labeled fluralaner dose of 25 mg/kg body weight), while six control dogs received no treatment. Mosquitoes were fed on blood that was collected from each dog prior to treatment and weekly for 15 weeks post-treatment to assess the continued effects of fluralaner as its serum level decreased. Mosquito fitness was assessed by three parameters: rate of successful blood-feeding, survival, and egg laying. RESULTS: Successful blood-feeding rate was similar between control and treatment groups. In the fluralaner treatment, mosquito survival was significantly reduced within the first 24 h after blood-feeding, for the first 12 weeks post-treatment of the dogs (efficacy range = 33.2-73.3%). Survival of mosquitoes up until a potentially heartworm-infective timepoint (14 days post-blood-feeding) was significantly reduced in the fluralaner-treated group at several timepoints (1, 2, 5, 11, 12, 13, 14, and 15 weeks post-treatment; efficacy range = 49.4-91.4%), but was less consistently reduced at the other timepoints. Egg laying by mosquitoes was almost completely suppressed for the first 13 weeks following treatment of the dogs with fluralaner (treatment efficacy ≥ 99.8%). CONCLUSIONS: Mosquitoes fed blood from fluralaner-treated dogs experienced a significant reduction in survival and fecundity. These findings support the potential for a reduction in heartworm transmission directly by lethal effects on the vector and indirectly through a reduction of the local vector population when mosquitoes are exposed to animals treated with fluralaner.

Efficacy of fluralaner chewable tablets (Bravecto®) against Asian longhorned tick (Haemaphysalis longicornis) infestations of dogs.

BACKGROUND: The parthenogenic reproductive ability of Haemaphysalis longicornis, facilitating quick life cycle completion and rapid geographic spread and its pathogen vector potential make infestations a risk to human and canine health. Two 90-day studies were initiated to evaluate the efficacy of a single fluralaner administration for the treatment and prevention of H. longicornis infestations on dogs. METHODS: Dogs were randomly assigned (10 dogs/group) to either an untreated control group or a group treated once (Day 0) with 13.64% w/w fluralaner chewable tablets (Bravecto®) at the minimum label dose rate of 25 mg/kg. Each dog was infested with approximately 50 H. longicornis ticks on Days -9 or -6 and on Days -2, 28, 58 and 88. A different US tick isolate was used in each study. Tick counts were completed on Days -7 or -4, 2, 30, 60 and 90. The primary efficacy criterion was a 90% reduction in arithmetic mean tick counts between the treated and control groups. For between-group comparisons at any assessment, at least six control dogs were required to retain at least 25% of the infestation dose (13 live ticks). RESULTS: Pre-study infestations demonstrated susceptibility of all study dogs to challenge with H. longicornis. At each subsequent assessment in both studies, at least seven untreated control dogs retained ≥ 25% of the challenge, demonstrating adequate infestations for each efficacy calculation. On Days 2, 30, 60 and 90 the mean live tick infestation rate (number of ticks recovered from each dog/infesting challenge of each dog) of untreated control dogs ranged from 27.8 to 60.8%. No live ticks, free or attached, were found on any fluralaner-treated dog in either study. Between-group differences were statistically significant (P ≤ 0.0002) at each assessment. CONCLUSION: At the minimum recommended label dose rate of 25 mg/kg, fluralaner chewable tablets were 100% effective in eliminating H. longicornis ticks from dogs infested at the time of treatment. Complete efficacy against both US isolates of this tick was maintained through 90 days following a single treatment. Therefore, fluralaner is a treatment of choice for protecting dogs against this invasive tick species.

Efficacy of two topical fluralaner formulations (Bravecto®; Bravecto® Plus) against Asian longhorned tick (Haemaphysalis longicornis) infestations of cats.

BACKGROUND: The invasive tick species, Haemaphysalis longicornis, is becoming established in the USA, presenting a growing threat to dogs and cats. Two 90-day studies were initiated, the same protocol in each, to confirm the efficacy of a single application of two fluralaner formulations against H. longicornis infestations of cats. METHODS: Cats were randomized among three groups in a 1:1:1 ratio (10 cats/group). Group 1 cats were untreated controls; Group 2 cats were treated with a topical fluralaner formulation (Bravecto®); Group 3 cats received a topical formulation containing fluralaner and moxidectin (Bravecto® Plus). Treatments were administered once (Day 0) at the label dose rates. Each cat was infested with 50 H. longicornis ticks on Day 7 for study qualification and also infested with 50 ticks on Days 2, 28, 58 and 88. Tick counts were completed on Days 5, 2, 30, 60 and 90. The primary objective was based on percentage reductions in arithmetic mean tick counts. RESULTS: Pre-study infestations showed all study cats were susceptible to tick challenge. Except for Day 2 in one study, at least six control cats retained ≥ 25% of each challenge, demonstrating an adequate infestation for efficacy assessments. Across studies on Days 2, 30, 60 and 90, the mean live tick infestation rate (number of ticks recovered from each cat/infesting challenge to each cat) of Group 1 cats ranged from 25.0 to 69.6%. Efficacy of each formulation, based on live tick counts, was 100% on Day 2 and > 95 to 100% at each subsequent assessment. Between-group differences were statistically significant (P < 0.0001) for each treatment versus control comparison. CONCLUSION: At the label dose rate, both topical fluralaner formulations were 100% effective in eliminating H. longicornis ticks from cats infested at the time of treatment. Efficacy of > 95 to 100% was then maintained through 90 days following a single application. Fluralaner is therefore a treatment of choice for protecting cats against this invasive tick species.

Fluralaner 5.46% (w/w) flavored chewable tablet (Bravecto® 1-Month) is effective for treatment of canine generalized demodicosis.

BACKGROUND: Orally administered fluralaner (13.64% w/w) is effective for treating canine generalized demodicosis. A study was initiated to assess the efficacy of a novel 5.46% w/w fluralaner chewable tablet formulation for monthly administration in the treatment of this disease. METHODS: Client-owned dogs diagnosed with generalized demodicosis were acclimatized to laboratory conditions and randomized to receive either orally administered fluralaner (Bravecto® 1-Month) (10.0 to 14.4 mg/kg body weight) (n = 8) or topical imidacloprid-moxidectin (Advocate® for dogs, Elanco) applied per label on days 0, 28, and 56 (n = 8), or more frequently for ongoing severe demodicosis. On days -2, 28, 56, and 84, deep skin scrapings were taken from five sites on each dog for mite identification and counting, and semiquantitative clinical assessments of generalized demodicosis were recorded. Primary efficacy was based upon arithmetic mean mite count reductions relative to pre-treatment. RESULTS: By day 28, mean pre-treatment mite counts, > 600 in both groups, were significantly reduced by 99.7% and 89.5% (both P < 0.001) in the fluralaner and imidacloprid-moxidectin groups, respectively. Parasitological cure (100% reduction in mite counts on days 56 and 84) was achieved in all fluralaner-treated dogs (100%) and in two imidacloprid-moxidectin-treated dogs (25%). In the imidacloprid-moxidectin group, the reduction in mean mite counts was 89.5% (day 28), 94.4% (day 56), and 97.5% (day 84). All study dogs were free of crusts on days 56 and 84. Scales resolved by day 84 in all fluralaner-treated dogs and in three imidacloprid-moxidectin-treated dogs. All fluralaner-treated dogs and five imidacloprid-moxidectin-treated dogs had > 90% hair regrowth on day 84. CONCLUSION: Three consecutive monthly orally administered treatments with fluralaner (5.46% w/w) flavored chewable tablets (minimum dose rate 10 mg/kg body weight) eliminated Demodex canis mites from dogs diagnosed with generalized demodicosis.

Evaluation of oral fluralaner (Bravecto®) for efficacy against nymphs of Amblyomma americanum and Rhipicephalus sanguineus (sensu lato).

BACKGROUND: Amblyomma americanum and Rhipicephalus sanguineus (sensu lato) nymphs commonly feed on and transmit pathogens to dogs (Canis familiaris). Control of immature and adult tick life stages is necessary to fully protect animals. We evaluated efficacy of oral fluralaner (Bravecto®) against induced infestations with A. americanum and R. sanguineus (s.l.) nymphs on dogs in two experiments. METHODS: In each experiment, 10 dogs were administered oral fluralaner chewable tablets one time on Day 0 at a targeted minimum dose of 25 mg/kg body weight and 10 dogs remained non-treated controls. Dogs were infested with two groups of 50 A. americanum nymphs and two groups of 50 R. sanguineus (s.l.) nymphs on Days -1, 6, 28, 56 and 84. At 48 h and 72 h post-infestation, nymphs were collected from dogs, assessed as live or dead, and enumerated into categories defining attachment and engorgement status. Fluralaner efficacy was determined in separate analyses against all live nymphs and against live-fed nymphs, i.e. live nymphs that were attached to dogs at the time of collection and/or were engorged. Fluralaner was considered effective when mean numbers of live ticks were reduced in fluralaner-treated dogs by ≥ 90%. RESULTS: Fluralaner efficacy against all live and live-fed A. americanum nymphs in the first experiment was > 94% on all collection days. Efficacy against all live R. sanguineus (s.l.) nymphs in the first experiment was > 96% on all collection days  excluding the 48 h counts for infestations on Days 28 (83.7%), 56 (82.9%) and 84 (86.7%); efficacy against live-fed R. sanguineus (s.l.) nymphs was > 95% on all 48 h/72 h count days. Fluralaner efficacy against all live A. americanum nymphs in the second experiment was > 93% on all collection days for 8 weeks excluding the 48 h count for infestation on Day 56 (87.8%); efficacy against live-fed A. americanum nymphs was > 91% on all count days for 8 weeks. Efficacy against all live R. sanguineus (s.l.) nymphs in the  second experiment was > 91% on all 72 h collection days  except for infestations on Days 28 (76.8%) and 56 (86.3%); efficacy against live-fed R. sanguineus (s.l.) nymphs was 100% on all 72 h count days. CONCLUSIONS: A single administration of oral fluralaner to dogs is effective against A. americanum and R. sanguineus (s.l.) nymphs for up to 12 weeks.

Nanoencapsulated deltamethrin as synergistic agent potentiates insecticide effect of indoxacarb through an unusual neuronal calcium-dependent mechanism.

The use of neurotoxic chemical insecticides has led to consequences against the environment, insect resistances and side-effects on non-target organisms. In this context, we developed a novel strategy to optimize insecticide efficacy while reducing doses. It is based on nanoencapsulation of a pyrethroid insecticide, deltamethrin, used as synergistic agent, combined with a non-encapsulated oxadiazine (indoxacarb). In this case, the synergistic agent is used to increase insecticide efficacy by activation of calcium-dependant intracellular signaling pathways involved in the regulation of the membrane target of insecticides. In contrast to permethrin (pyrethroid type I), we report that deltamethrin (pyrethroid type II) produces an increase in intracellular calcium concentration in insect neurons through the reverse Na/Ca exchanger. The resulting intracellular calcium rise rendered voltage-gated sodium channels more sensitive to lower concentration of the indoxacarb metabolite DCJW. Based on these findings, in vivo studies were performed on the cockroach Periplaneta americana and mortality rates were measured at 24 h, 48 h and 72 h after treatments. Comparative studies of the toxicity between indoxacarb alone and indoxacarb combined with deltamethrin or nanoencapsulated deltamethrin (LNC-deltamethrin), indicated that LNC-deltamethrin potentiated the effect of indoxacarb. We also demonstrated that nanoencapsulation protected deltamethrin from esterase-induced enzymatic degradation and led to optimize indoxacarb efficacy while reducing doses. Moreover, our results clearly showed the benefit of using LNC-deltamethrin rather than piperonyl butoxide and deltamethrin in combination commonly used in formulation. This innovative strategy offers promise for increasing insecticide efficacy while reducing both doses and side effects on non-target organisms.

Efficacy of a spot-on combination of fluralaner plus moxidectin (Bravecto® Plus) in cats following repeated experimental challenge with a field isolate of Ctenocephalides felis.

BACKGROUND: A spot-on formulation of fluralaner plus moxidectin has been designed to provide long-term protection against fleas and ticks, prevent heartworm disease and treat gastrointestinal nematode infections in cats. The objective of this study was to determine the efficacy of this product against fleas collected from a household with repeated fipronil failures following owner-administered treatments. METHODS: Thirty cats were randomized to three equal groups: (A) untreated controls; (B) to receive a single application of fluralaner plus moxidectin (Bravecto® Plus) at 40 mg/kg and 2 mg/kg body weight, respectively; and (C) three applications at one month intervals with a spot-on formulation of fipronil and (S)-methoprene (Frontline® Plus) at 0.5 ml manufacturer recommended dose. Flea challenges were completed on Days -6 (for randomization), -1, 7, 14, 28, 42, 56, 70, 77, 84 and 91. Flea counts were completed 48 hours after initial treatment and 48 hours following each subsequent challenge. RESULTS: Fleas were found on all control and all fipronil and (S)-methoprene treated cats at every assessment. From Day 2 to Day 93, all cats in the fluralaner plus moxidectin group were flea-free, with one exception (Day 58; three fleas counted on one cat); control group flea counts ranged between 34-109, and fipronil and (S)-methoprene group counts ranged between 1-79. At each assessment after Day 0, compared to the control group, geometric mean flea counts were significantly lower in the fipronil and (S)-methoprene group (P ≤ 0.04) and in the fluralaner plus moxidectin group (P < 0.001), and mean flea counts in the fluralaner plus moxidectin group were significantly lower than those of the fipronil and (S)-methoprene group (P < 0.001). The efficacy of fluralaner plus moxidectin, based on geometric means, was 100% at each assessment post-Day 0 except on Day 58 when efficacy was 99.7%. In the fipronil and (S)-methoprene group efficacy ranged between 30.6-65.6%. CONCLUSIONS: These findings demonstrate complete efficacy of fluralaner plus moxidectin against a flea isolate that was not controlled by fipronil and (S)-methoprene. This study provides confirmation of the consistent, sustained efficacy of topically applied fluralaner in the treatment and control of flea infestations in cats.

Investigation of the efficacy of fluralaner spot-on (Bravecto®) against infestations of Ixodes holocyclus on cats.

BACKGROUND: Infestation of cats with the Australian paralysis tick, Ixodes holocyclus continues to be a threat because of the paralysis that can result from attachment of just a single tick. The outcome can be fatal, particularly if tick removal and treatment is not initiated soon after the onset of paralysis. However, there are no published studies to guide veterinarians and owners on preventive measures. A study was therefore initiated to determine the efficacy of a systemically-acting, spot-on formulation of fluralaner (Bravecto®) for cats against existing I. holocyclus infestations, and to investigate the duration of protection following a single administration. METHODS: Healthy domestic cats, short or long-hair, immunized against holocyclotoxin, were randomly allocated to two groups of 10 cats per group, to receive either a single topically applied fluralaner treatment or no treatment. Fluralaner treatments were administered on Day 0 at a dose rate of 40 mg/kg. All cats were infested with 10 adult unfed female I. holocyclus on Day -1 and on Days 14, 28, 42, 56, 70 and 84. Ticks were assessed at 24 and 48 h after fluralaner treatment and 24, 48 and 72 hours after each subsequent re-infestation. Ticks were counted but not removed at the 24- and 48-h post-challenge assessments and were removed following the 72-h counts. RESULTS: The efficacy of fluralaner spot-on against an existing I. holocyclus infestation was 100% at 48 h post treatment. Following re-infestations, efficacy remained at 100% at the 72-h assessments for all challenges from Day 14 to Day 84. Differences between mean live tick counts on treated versus control cats were significant at all time points from the first post-treatment assessment (t-test: t(18) = 23.162; P < 0.0001) through the final challenge on Day 84 (t-test: t(18) = 21.153; P < 0.0001). No treatment-related adverse events were observed and there were no abnormal observations at the product application sites. CONCLUSIONS: A single treatment of fluralaner spot-on was well tolerated and provided 100% efficacy against I. holocyclus ticks for at least 84 days. Fluralaner spot-on can be a valuable tool to prevent tick infestation in cats, and to control the risk of I. holocyclus-induced paralysis.

A randomized, blinded, controlled USA field study to assess the use of fluralaner topical solution in controlling feline flea infestations.

BACKGROUND: Fleas are a common ectoparasite of domestic cats and there is a need for novel treatments that improve feline flea control. METHODS: This investigator-blinded, multi-center randomized, positive-controlled study evaluated the flea control in cats provided by a single owner-applied treatment with a fluralaner topical formulation compared with a positive control. Households with up to five healthy cats, all at least 12 weeks of age and weighing at least 1.2 kg (2.6 lb), were randomized in an approximate 3:1 ratio of fluralaner to positive control. All cats in households randomized to the positive control group were dispensed three treatments, at 4-week intervals, of a commercial formulation of fipronil/(S)-methoprene. All cats in households randomized to the fluralaner group were dispensed an initial treatment at enrollment and a second treatment at week 12 for an additional 3-week observation of treatment safety. One primary cat with at least five live fleas at enrollment was randomly selected within each household. Flea counts were performed on all primary cats at 4-week intervals through week 12. Efficacy measurement was based on reduction in flea counts from baseline. Treatment was considered effective at weeks 4, 8 and 12 if mean live flea count reductions were 90% or greater and statistically significantly different (P ≤ 0.05) from counts at enrollment. RESULTS: In 18 investigational veterinary clinics across 11 USA states, 116 households (224 cats) were randomized to receive topical fluralaner and 45 households (87 cats) were randomized to the fipronil-methoprene combination. Fluralaner was demonstrated to be effective at 4 weeks (99.1% flea count reduction), 8 weeks (99.5%), and 12 weeks (99.0%), and all reductions were significantly different from the enrollment count (all P < 0.0001). The fipronil-methoprene combination was < 90% effective at each post-treatment assessment, with peak efficacy of 75.4% at 12 weeks (all P < 0.0001). No treatment-related serious adverse events were reported in either group. CONCLUSIONS: Owner-applied fluralaner topical treatment was safe in cats and was highly effective in killing fleas over the subsequent 12 weeks.

A randomized, blinded, controlled USA field study to assess the use of fluralaner topical solution in controlling canine flea infestations.

BACKGROUND: Orally administered fluralaner effectively controls fleas and ticks on dogs for 12 weeks. This study evaluates the flea control efficacy achieved with topically applied fluralaner in dogs. METHODS: This investigator-blinded, multi-center randomized, positive controlled study evaluated flea control efficacy in dogs following a single owner-applied treatment of topical fluralaner. A positive control group received three treatments, at 4-week intervals, of a commercial formulation of fipronil/(S)-methoprene. All dogs in households randomized to the fluralaner group were dispensed an initial treatment at enrollment and a second treatment at week 12 for an additional 3-week observation of treatment safety. Households with up to five healthy dogs, all at least 12 weeks of age and weighing at least 2 kg (4.4 lb), were randomized in a ratio of 3:1 of fluralaner to positive control. Within households, one primary dog with at least 10 live fleas at enrollment was randomly selected. Flea counts were performed on all primary dogs every 4 weeks through week 12. Efficacy measurement was based on reduction from baseline flea counts. Treatment was considered effective if geometric mean live flea count reductions at weeks 4, 8, and 12 were 90% or greater and significantly different from counts at enrollment. In addition, for each time point the arithmetic mean live flea counts, the efficacy based on arithmetic means, the number and percentage of dogs with at least a 90% reduction in flea count, and the number and percentage of flea free dogs were calculated. Statistical comparisons were also made between treatment groups. RESULTS: At 12 sites, across 10 states, 121 households (221 dogs) were randomized to receive fluralaner and 44 households (100 dogs) were randomized to receive the positive control. Fluralaner was demonstrated to be significantly effective (all P ≤ 0.0001) at 4 weeks (99.8% reduction), 8 weeks (99.9%), and 12 weeks (99.9%). The positive control was significantly different from baseline (all P ≤ 0.0001) and showed a reduction of 81.2% at 4 weeks and was effective at 8 weeks (90.3%) and 12 weeks (93.0%). Arithmetic mean flea count reductions for the fluralaner group at 4, 8, and 12 weeks were 99.8, 99.9, and 99.9%, respectively. For the positive control, arithmetic mean flea count reductions were 58.8, 75.3, and 80.8% at 4, 8, and 12 weeks, respectively. No treatment-related serious adverse events were reported in either group. CONCLUSIONS: Owner-applied topical fluralaner treatment was safe in dogs and provided ≥ 99.8% flea control efficacy for 12 weeks.

A randomized, blinded, controlled USA field study to assess the use of fluralaner tablets in controlling canine flea infestations.

BACKGROUND: The novel isoxazoline molecule fluralaner provides 12 weeks activity against fleas and 8 to 12 weeks against tick infestations according to label claims. METHODS: This blinded, multi-center study in client-owned dogs evaluated the flea control provided by a single oral fluralaner treatment (25-56 mg/kg; Bravecto™, Merck Animal Health) compared to a control group administered three oral spinosad (30 - 60 mg/kg; Comfortis®, Elanco) treatments at 4-week intervals together with an amitraz collar (9%, Preventic®, Virbac). Households were randomized (3:1 ratio) to either fluralaner (224 dogs, 118 households) or control (70 dogs, 39 households). Within households, one primary dog with at least 10 live fleas at enrollment was randomly selected for whole body flea counts every 4 weeks through Week 12; all dogs were followed for safety until Week 12. Fluralaner dogs received two additional doses at Weeks 12 and 24 for further safety and palatability observations through Week 26. RESULTS: Geometric mean flea count reductions from baseline for the fluralaner group at Weeks 4, 8, and 12 were 99.7%, 99.8%, and 99.8%, respectively; and 96.1%, 99.5%, and 99.6% for the spinosad controls. Percentages of flea-free primary dogs at Weeks 4, 8, and 12 were 91.1%, 95.4%, and 95.3% for the fluralaner group; and 44.7%, 88.2%, and 84.4% for the controls; the differences were significant at Weeks 4 (P < 0.0001) and 12 (P = 0.0370). Improvements in veterinarian assessed flea allergy dermatitis (FAD) were observed in both groups. Fluralaner tablets were accepted free choice in over 90% of doses. The most common adverse event was vomiting, occurring in 7.1% of the fluralaner group and 14.3% of the controls. No treatment related serious adverse events were reported. CONCLUSIONS: A single treatment of dogs with the palatable fluralaner flavored chewable tablet provides a safe and effective option for 12 weeks of flea control at least equivalent to that of 3 sequential treatments with spinosad tablets. Linked to the high level of flea control was a substantial alleviation of associated signs of FAD.

Measurement of the temporal transferability of indoxacarb to cotton gloves from spot-on treated dogs.

The objectives of the studies reported herein were to (1) determine the minimum number of petting simulations required to load the maximum amount of test substance (indoxacarb) residue onto cotton gloves (the sampling medium) from spot-on treated dogs; and (2) using the number of petting simulations that resulted in maximal transfer, to conduct a second study that measured amount of residue dislodged via petting a dog as a function of the time interval after application. Maximal percent transfer of indoxacarb from spot-on treated dogs occurred after 10 repetitive petting simulations (consisting of 3 directional pet strokes each) and was approximately 1-2% of amount applied. Temporal measurements of mean indoxacarb transferability followed an exponential decay function, beginning at approximately 2% transfer on the day of application, and declining to 0.08% by d 30 post treatment.