Efficacy of a topically applied formulation of metaflumizone on cats against the adult cat flea, flea egg production and hatch, and adult flea emergence

A spot-on metaflumizone formulation was evaluated to determine its adulticidal efficacy, effect upon egg production, and ovicidal activity when applied to flea infested cats. Eight male and eight female adult domestic shorthair cats were randomly assigned to either serve as non-treated controls or were treated topically with a minimum of 40mg/kg metaflumizone in single spot-on Day 0. On Days -2, 7, 14, 21, 28, 35, 42, 49, and 56, each cat was infested with approximately 100 unfed cat fleas, Ctenocephalides felis felis. On Days 1, 2, and 3, and at 48 and 72h after each post-treatment reinfestation, flea eggs were collected and counted. At approximately 72h after treatment or infestation, each cat was combed to remove and count live fleas. Egg viability was determined by examining hatched eggs after 5 days and adult emergence was determined 28 days after egg collection. Metaflumizone provided >/=99.6% efficacy against adult fleas from Days 3 to 45 following a single application. Following treatment, egg production fell by 51.6% within 24h and 99.2% within 48h. Following subsequent weekly infestations egg production from treated cats was negligible out to Day 38, with >/=99.5% reduction relative to non-treated cats. Where there were eggs to evaluate, metaflumizone treatment did not have any apparent effect on the hatching of eggs or on the development and emergence of adult fleas from the eggs produced by fleas from treated animals.     

Evaluation of the effects of selamectin against adult and immature stages of fleas (Ctenocephalides felis felis) on dogs and cats

The adulticidal, ovicidal, and larvicidal effects of selamectin against flea (Ctenocephalides felis felis) infestations on dogs and cats were evaluated in a series of seven controlled and masked studies (three in cats, four in dogs). Animals were randomly allocated to treatment with either selamectin at a minimum dosage of 6mgkg(-1) in the commercial formulation or one of two negative-controls (0.9% NaCl solution or the vehicle from the commercial formulation). Treatments were administered topically in a single spot on the skin at the base of the neck in front of the scapulae. Speed of kill, measured by flea comb counts at 12h intervals during the 48h immediately following a single treatment on day 0, was evaluated in two studies. One study was in dogs and the other in cats, and each animal was infested with approximately 100 unfed viable adult fleas prior to treatment. Reductions in geometric mean flea counts for selamectin compared with saline were >98% between 24 and 36h after treatment in dogs, and between 12 and 24h after treatment in cats (P< or =0.0006). Efficacy in reducing flea egg hatch and larval development was evaluated in four studies, in which dogs and cats were treated once on day 0 and then repeatedly infested with approximately 600 fleas. Flea eggs were collected approximately for 72h after each infestation, on days 3, 7, 14, 21, and 30, counted, and cultured to determine their hatchability and subsequent larval development. Compared with the vehicle, selamectin was highly effective in reducing flea egg hatch (>92% in cats) and larval development (> or =95% for dogs and cats), and emergence of adults (97.8-100% for dogs, 85.6-100% for cats) for 30 days. Effects of exposure to hair coat debris were investigated in a study with dogs treated once on day 0 and repeatedly infested with 100 adult fleas. Debris (dander, flea faeces, hair, scales) was collected on days 1, 7, 14, 21, and 30 and added to normal flea eggs or larvae for incubation. Compared with debris from vehicle-treated dogs, debris from selamectin-treated dogs was highly effective in preventing egg hatch (>96%), in killing larvae (>98%) and in preventing larval development to adults (>99%) (P相似文献   

Evaluation of the comparative efficacy of selamectin against flea (Ctenocephalides felis felis) infestations on dogs and cats in simulated home environments

The comparative efficacy of monthly administration of selamectin or lufenuron against Ctenocephalides felis felis on dogs and cats was evaluated over a 5-month period in flea-infested environments. Twenty-four dogs and 32 cats were randomly allocated to receiving a topical treatment with selamectin or an oral administration of tablets containing lufenuron/milbemycin oxime (for dogs) or lufenuron only (for cats). Each product was administered in accordance with the manufacturer's label recommendations. Eight dogs and four cats served as untreated sentinels. Treatments were administered on days 0, 30, 60, 90, and 120. Each animal received an application of 100 fleas on days -28 and -21, and then weekly applications of 20 fleas from days 91 through 147. Flea comb counts were performed on day -6, and every 2 weeks after day 0. From day 29 (dogs) or day 44 (cats) to day 150, geometric mean flea counts for selamectin were < or =0.4. Mean flea counts for animals assigned to treatment with selamectin were significantly lower (P=0.0001) than for animals assigned to treatment with lufenuron at all assessments after day 0.     

Efficacy of selamectin and fipronil-(S)-methoprene spot-on formulations applied to cats against adult cat fleas (Ctenocephalides felis), flea eggs, and adult flea emergence

A study was conducted to evaluate the efficacy of selamectin and fipronil-(S)-methoprene against adult cat fleas (Ctenocephalides felis), flea egg production, and the viability of flea eggs collected from treated cats. Cats were infested with approximately 50 adult fleas 2 days before treatment and weekly thereafter; flea eggs were collected and counted on days 0, 1, 2, and 3 and 48 and 72 hours after each weekly flea infestation. Live fleas were collected approximately 72 hours after treatment or infestation. Compared with fipronil-(S)-methoprene, selamectin provided significantly greater control of adult fleas from days 24 to 31 and significantly greater reduction in egg production from days 16 to 45. For the most part, both products significantly impacted larval and adult emergence for the entire 6-week study, with fipronil-(S)-methoprene providing significantly greater reduction in larval and adult emergence at week 6.     

Evaluation of efficacy of selamectin and fipronil against Ctenocephalides felis in cats

OBJECTIVE: To evaluate efficacy of monthly administration of selamectin and fipronil against Ctenocephalides felis in cats. DESIGN: Randomized controlled trial. ANIMALS: 36 healthy cats. PROCEDURE: Cats known to be free of fleas were infested with 100 unfed adult fleas on days -28 and -21. On days 0, 30, 60, 90, and 120, sixteen cats (8 pairs/treatment group) were treated by topical administration of selamectin (6 mg/kg [2.7 mg/lb] of body weight) or fipronil (7.5 mg/kg [3.4 mg/lb]). Four control cats (2 pairs) were not treated. On day -6 and every 2 weeks after initial treatment, comb counts were performed to detect fleas. Flea counts were recorded, and fleas (< or =50) that had been removed were replaced onto the cat. On day 89, fleas were not replaced. On day 91 and every 7 days until the end of the study (day 150), cats were challenged with 20 adult fleas. Flea counts were compared between and within treatments. RESULTS: 14 days after treatment, geometric mean flea counts were reduced by 71.2% by fipronil treatment and 35.3% by selamectin treatment. Both treatments resulted in 97 to 98% reduction in flea counts on day 29 and 99.8 to 100% reduction from day 44 to the end of the study. CONCLUSIONS AND CLINICAL Relevance: Selamectin is as effective as fipronil in treating infestation in cats housed for 3 months in a flea-infested environment under conditions known to support the flea life cycle and in protecting against subsequent weekly challenges with C felis for an additional 2 months.     

Efficacy of a topically applied spot-on formulation of a novel insecticide, metaflumizone, applied to cats against a flea strain (KS1) with documented reduced susceptibility to various insecticides

A spot-on metaflumizone formulation was evaluated in adult domestic short hair cats to determine its adultidical efficacy against a flea strain that has reduced susceptibility to a number of insecticides. Eight cats served as non-treated controls, eight cats were treated with a metaflumizone formulation at 0.2 ml/kg (40 mg metaflumizone/kg) and eight cats were treated with fipronil 10% w/v-(s)-methoprene 12%w/v at 0.075 ml/kg (7.5-7.7 mg fipronil/kg:9.0-9.2 mg (s)-methoprene/kg). On days -1, 7, 14, 21, 28, 35, and 42 each cat was infested with approximately 100 unfed KS1 cat fleas, Ctenocephalides felis. At approximately 48 h after treatment or infestation, each cat was combed to remove and count live fleas. Treatment with metaflumizone provided > or = 99.3% efficacy for 3 weeks post-treatment and then 97.4, 91.4 and 86.2% efficacy at 4, 5 and 6 weeks post-treatment, respectively. Fipronil-(s)-methoprene provided 99.6% efficacy at 1 week post-treatment and then 97.6, 96.4, 71.3, 22.0 and 13.1% efficacy at weeks 2, 3, 4, 5 and 6, respectively. The reductions in flea numbers were significantly greater for the metaflumizone treatment than for fipronil-(s)-methoprene from 3 to 6 weeks after treatment.     

Host association, on-host longevity and egg production of Ctenocephalides felis felis

Host association, on-host longevity and egg production of Ctenocephalides felis felis (Bouché) were evaluated using fleas from a commercial laboratory colony and first generation, laboratory-reared, native Indiana fleas. Fleas were placed on cats that were declawed, fitted with Elizabethan collars and housed in specially designed metabolic cages. An average of 85% of the female and 58% of the male fleas stayed continuously on the cats for at least 50 days, indicating that the cat flea is a permanent ectoparasite. The maximum longevity of the cat flea was not determined, but it was shown that it can survive and reproduce on the cat for at least 113 days. A female cat flea may produce up to 1745 eggs during a 50-day period.     

Evaluation of the CatanDog's tag to prevent flea infestations, inhibit flea reproduction or repel existing flea infestations on cats

To evaluate the ability of the CatanDog's tag to eliminate fleas, inhibit egg production and prevent flea infestations, six domestic shorthaired cats were randomly allocated to two treatment groups and housed individually in stainless steel metabolic cages. Three cats were each fitted with a CatanDog's tag; the other three cats were not fitted with tags and served as controls. Following a 42-day acclimation period, each of the six cats was infested with 100, 1-3 day post-emergence, adult Ctenocephalides felis felis (Bouché) on days 0, 7, 14, 21, and 27. Flea egg production was determined by collecting and enumerating eggs 2, 4 and 6 days after each infestation. Viability of eggs was determined by placing 100 eggs recovered from each cat in rearing media in an insect rearing chamber and determining adult emergence at 28 days. Adult fleas were recovered from cats 6 days post-infestation by thoroughly combing each cat to remove fleas. To determine if the tags provided protection from infestation, the six cats were placed into a 8.53mx4.36 m room with 400 cat fleas for 3h. Cats were then combed to remove and enumerate fleas. The CatanDog's tags had no significant effect upon egg production, egg viability, or adult fleas infesting cats. In addition there was no difference in the numbers of fleas recovered from the cats placed in the flea-infested room.     

Effect of 0.29% w/w fipronil spray on adult flea mortality and egg production of three different cat flea, Ctenocephalides felis (Bouché), strains infesting cats.

To evaluate the effect of fipronil spray on adult flea mortality and flea egg production of three different cat flea, Ctenocephalides felis (Bouché) strains, 30 domestic short hair cats were randomly allocated into six groups of five cats each. On day 0, cats in groups 2, 4 and 6 were treated with fipronil at 5-6ml/kg. Cats in groups 1, 3 and 5 served as untreated controls. On days -2, 7, 14, 21, and 28 each cat was infested with 50 adult cat fleas. Groups 1 and 2 were infested with fleas from the Kansas1 Colony (KS1) strain. Groups 3 and 4 were infested with a recently colonized cat flea strain from Florida (R6). Groups 5 and 6 were infested with fleas from the ARC strain. The adulticidal activity of fipronil was determined by flea comb counts 48h after treatment and then 48h after each reinfestation. Any flea eggs produced during the infestations were collected and counted prior to the 48h comb counts. Fipronil spray was > or = 99.5% effective against adults of all three cat flea strains when applied during an active infestation. Fipronil spray provided > or = 98.2 and > or = 99.5% control of adult fleas and egg production, respectively, for all strains through week 2. On days 23 and 30 control of R6 adults and egg production was significantly lower than either the ARC or the KS1 strain. On day 30, control of R6 adults and egg production was 77.3 and 87.3%, respectively. Control of KS1 adults and egg production on day 30 was significantly lower than the ARC strain. Fipronil provided > or = 99.5 and > or = 99.9% control of ARC fleas and egg production, respectively, throughout the entire study. The susceptibility to fipronil for the three strains was also evaluated on filter paper pesticide bioassays. The R6 strain was found to be less susceptible than the KS1 and ARC strains. The LC(95) estimates for the strains were 10.13, 4.77 and 2.62mg/m(2) for the R6, ARC and KS1 strains, respectively.     

Efficacy of a novel formulation of metaflumizone for the control of fleas (Ctenocephalides felis) on cats

A novel spot-on formulation containing metaflumizone (ProMeris for Cats, Fort Dodge Animal Health, Overland Park, KS) was evaluated in five laboratory studies to determine the duration of residual efficacy in cats against fleas after a single spot treatment. In each study, eight domestic shorthair cats were randomly allocated to each treatment group and individually housed. One group in each study remained non-treated. In one study, an additional group of eight cats was treated with a placebo formulation. Cats were treated topically with metaflumizone formulation to provide a dose of at least 40mg metaflumizone/kg. Cats were infested with 100 cat fleas (Ctenocephalides felis felis) once per week for approximately 8 weeks. Cats were comb counted 48h after treatment and each infestation to determine the number of viable fleas present. There were no significant differences in flea counts between the non-treated control and the placebo-treated control (P>0.05) other than a 26% reduction at week 1, demonstrating that the formulation excipients had no activity. Metaflumizone treatment resulted in significantly lower flea numbers relative to non-treated controls on all post-treatment count days (P<0.05). Metaflumizone provided >90% control of flea infestations up to 7 weeks following a single treatment.     

Imidacloprid/moxidectin topical solution for the prevention of heartworm disease and the treatment and control of flea and intestinal nematodes of cats

Sixteen controlled laboratory studies, involving 420 kittens and cats, were conducted to evaluate the efficacy and safety of topically applied formulations of imidacloprid and moxidectin for the prevention of feline heartworm disease, treatment of flea infestations and treatment and control of intestinal nematodes. Unit-dose applicators and the dosing schedule used in these studies were designed to provide a minimum of 10mg imidacloprid and 1mg moxidectin/kg. Treatments were applied topically by parting the hair at the base of the skull and applying the solution on the skin. Imidacloprid treatment alone did not display activity against Dirofilaria immitis or intestinal nematodes and moxidectin treatment alone provided little or no activity against adult Ctenocephalides felis infestations. The formulation containing 10% imidacloprid and 1% moxidectin was 100% efficacious against the development of adult D. immitis infections when cats were treated 30 days after inoculation with third-stage larvae. A single treatment with this formulation also provided 88.4-100% control of adult C. felis for 35 days. Imidacloprid/moxidectin was 100% efficacious against adult Toxocara cati and 91.0-98.3% efficacious against immature adults and fourth-stage T. cati larvae. The formulation provided 98.8-100% efficacy against adult Ancylostoma and immature adults and third-stage A. tubaeforme larvae. Monthly topical application with 10% imidacloprid/1% moxidectin is convenient, efficacious and safe for the prevention of feline heartworm disease, treatment of flea infestation and for the treatment and control of intestinal nematode infections of cats.     

Efficacy of selamectin in the treatment and control of clinical signs of flea allergy dermatitis in dogs and cats experimentally infested with fleas

OBJECTIVE: To determine whether treatment with selamectin would reduce clinical signs of flea allergy dermatitis (FAD) in dogs and cats housed in flea-infested environments. DESIGN: Randomized controlled trial. ANIMALS: 22 dogs and 17 cats confirmed to have FAD. PROCEDURE: Animals were housed in carpeted pens capable of supporting the flea life cycle and infested with 100 fleas (Ctenocephalides felis) on days -13 and -2 and on alternate weeks with 10 to 20 fleas. On day 0, 11 dogs and 8 cats were treated with selamectin (6 mg/kg [2.7 mg/lb]). Dogs were retreated on day 30; cats were retreated on days 30 and 60. All animals were examined periodically for clinical signs of FAD. Flea counts were conducted at weekly intervals. RESULTS: Throughout the study, geometric mean flea counts exceeded 100 for control animals and were < or = 11 for selamectin-treated animals. Selamectin-treated cats had significant improvements in the severity of miliary lesions and scaling or crusting on days 42 and 84, compared with conditions on day -8, and in severity of excoriation on day 42. In contrast, control cats did not have any significant improvements in any of the clinical signs of FAD. Selamectin-treated dogs had significant improvements in all clinical signs on days 28 and 61, but in control dogs, severity of clinical signs of FAD was not significantly different from baseline severity at any time. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that topical administration of selamectin, even without the use of supplementary environmental control measures and with minimal therapeutic intervention, can reduce the severity of clinical signs of FAD in dogs and cats.     

Evaluation of efficacy of selamectin, fipronil, and imidacloprid against Ctenocephalides felis in dogs

OBJECTIVE: To evaluate efficacy of monthly administration of selamectin, fipronil, and imidacloprid against Ctenocephalides felis in dogs. DESIGN: Randomized controlled trial. ANIMALS: 44 healthy dogs. PROCEDURE: Dogs known to be free of fleas were infested with 100 unfed adult fleas on days -28 and -21. On days 0, 30, 60, 90, and 120, dogs (12/group) were treated by topical administration of selamectin (6 mg/kg [2.7 mg/lb] of body weight), fipronil (7.5 mg/kg [3.4 mg/lb]), or imidacloprid (10 mg/kg [4.5 mg/lb]); 8 untreated dogs were used as controls. On day -6 and every 2 weeks after initial treatment, comb counts of viable adult fleas were made, and fleas (< or =50/dog) were replaced onto the dog from which they were removed. On day 89, fleas were not replaced. On day 91 and every 7 days until the end of the study, dogs were challenged with 20 adult fleas. RESULTS: 14 days after initial treatment, geometric mean flea counts were reduced by 97.5 to 99.1 % for all treatments, compared with pretreatment counts on day -6. Selamectin, fipronil, and imidacloprid reduced geometric mean flea counts by 99.7 to 100% from day 29 to the end of the study. CONCLUSIONS AND CLINICAL RELEVANCE: Selamectin is as effective as fipronil and imidacloprid in reducing C felis infestation in dogs housed for 3 months in a flea-infested environment under conditions known to support the flea life cycle, and in protecting against subsequent weekly challenges with C felis for an additional 2 months.     

The difference in efficacy of ivermectin oral, moxidectin oral and moxidectin injectable formulations against an ivermectin-resistant strain of Trichostrongylus colubriformis in sheep

AIM: To evaluate the efficacy of ivermectin oral, moxidectin oral and moxidectin injectable formulations against an ivermectin-resistant strain of Trichostrongylus colubriformis in sheep. METHODS: Twenty-four mixed breed lambs were infected with 15,000 infective third-stage larvae of an ivermectin-resistant strain of T. colubriformis which had originally been isolated from a goat farm in Northland in 1997. Twenty-six days post infection, the lambs were divided into 3 treatment groups and a control group (n=6 lambs/group). Treatment consisted of either ivermectin oral formulation (0.2 mg/kg), moxidectin oral formulation (0.2 mg/kg), or moxidectin injectable formulation (0.2 mg/kg). Faecal egg counts (FECs) were determined at 0, 3, 5, 7 and 10 days after treatment. All animals were necropsied 12 days after treatment and worm counts were performed. Larval development assays were conducted 24 days post infection. A further 3 lambs were infected with 15,000 infective third-stage larvae of a fully susceptible strain of T. colubriformis for comparative purposes in the larval development assay. The efficacy of the moxidectin injectable formulation was also confirmed in these 3 lambs. RESULTS: The FEC reduction test at day 10 after treatment revealed 62%, 100% and 0% reductions in arithmetic-mean FECs for ivermectin oral, moxidectin oral and moxidectin injectable groups, respectively. The ivermectin oral, moxidectin oral and moxidectin injectable formulations achieved 62%, 98% and 4% reductions in arithmetic-mean worm burdens, respectively. Larval development assays showed resistance ratios for ivermectin of 4:1, avermectin B2 of 2.7:1, ivermectin aglycone of 37:1, moxidectin of 1.4:1, thiabendazole of 14.6:1 and levamisole of 1.8:1. CONCLUSIONS: The moxidectin oral formulation provided a high degree of control against ivermectin-resistant T. colubriformis whereas the moxidectin injectable formulation had very low efficacy. Ivermectin aglycone was the analogue of choice for diagnosis of ivermectin resistance in T. colubriformis in the larval development assay.     

Efficacy of selamectin in the treatment and prevention of flea (Ctenocephalides felis felis) infestations on dogs and cats housed in simulated home environments

The efficacy of selamectin, a novel avermectin, in protecting dogs and cats against experimentally induced environmental flea (Ctenocephalides felis felis) infestations, was evaluated in a series of controlled and masked studies. Purpose-bred shorthaired cats and Beagles were randomly allocated to treatment with either selamectin at a minimum dosage of 6mgkg(-1) of body weight in the commercial formulation or the negative control treatment (vehicle only), and housed in controlled simulated home environments capable of supporting the flea life cycle. Day 0 was defined as the first day of treatment. Treatments were administered topically in a single spot on the skin at the base of the neck in front of the scapulae. In environmental challenge studies, which were designed to evaluate the efficacy of selamectin in the treatment and control of established flea infestations, dogs and cats were each infested with 100 fleas on days -28 and -21 and placed in carpeted rooms in order to establish high levels of active flea infestation prior to day 0. Treatments were administered monthly for 3 months. Flea comb counts were performed on days 14, 29, 44, 59, 74, and 90. Reductions in geometric mean flea comb counts for selamectin, compared with vehicle, were >99% from day 14 onwards for dogs, and >92% on day 29 and >99% on days 44, 59, 74, and 90 for cats (P=0.0001). In prevention of environmental infestation studies, dogs and cats were placed in environments capable of supporting flea infestations and given monthly treatments for 2 months, commencing on day 0. Animals were infested with 100 fleas on days 1 and 7, and flea comb counts were performed on days 29, 44, and 60. Reductions in geometric mean flea comb counts for selamectin, compared with vehicle, were >99% on days 29, 44, and 60 (P=0.0001) for dogs and cats. Monthly administration of selamectin to dogs and cats housed in environments highly suited to completion of the flea life cycle was shown to be highly effective in the treatment and prevention of flea infestations, without the need for supplementary environmental control measures.     

Field efficacy of a 10 per cent pyriproxyfen spot-on for the prevention of flea infestations on cats

The clinical application of a new method for using the insect growth regulator, pyriproxyfen, for controlling flea populations in cat-owning homes is evaluated for the first time. In a multicentric, controlled and randomised trial, 107 flea-infested cats were treated with a minimum dose of 10 mg/kg bodyweight pyriproxyfen as a 10 per cent spot-on application on two occasions, with a three-month interval between doses. For comparison, 99 cats received lufenuron suspension orally, once a month, for six months. Flea counts decreased significantly over time in each group and were significantly lower in the pyriproxyfen group than in cats treated with the reference product. The percentage of 'zero-flea' cats increased from 49 per cent on day 30 to 88 per cent on day 180 in the pyriproxyfen group and from 30 to 71 per cent in the lufenuron group at the same time points (P<0.05). Appropriately timed topical applications of pyriproxyfen, therefore, offer a method of flea control in the domestic environment.     

New methods and strategies for monitoring susceptibility of fleas to current flea control products

A flea larval bioassay was developed by an international team of scientists to monitor the susceptibility of fleas (Ctenocephalides felis) to imidacloprid (Advantage, Bayer HealthCare). The assay was validated using laboratory and field isolates of C. felis. Flea eggs representing different field isolates of C. felis were collected by veterinarians in the United States, United Kingdom, and Germany. Of the 972 flea isolates obtained during the 5-year study, 768 contained sufficient numbers of eggs to conduct the larval bioassay. Greater than 5% survival occurred for only six of the field isolates evaluated. Further evaluation and analysis of these isolates demonstrated that they did not differ significantly in their susceptibility to imidacloprid from the reference strains used to develop the assay. Collections of field flea isolates will continue in an attempt to detect and document any change in the susceptibility of field flea populations to imidacloprid.     

Dose determination of a novel formulation of metaflumizone plus amitraz for control of cat fleas (Ctenocephalides felis felis) and brown dog ticks (Rhipicephalus sanguineus) on dogs

A novel spot-on formulation containing metaflumizone and amitraz (ProMeris/ProMeris Duo for Dogs, Fort Dodge Animal Health, Overland Park, KS) was evaluated in a laboratory study to determine the appropriate dose for efficacy against fleas and ticks on dogs for 1 month. Thirty-six Beagles were randomly allocated to six equal groups and individually housed. One group remained nontreated. Another was treated with a placebo formulation (solvents with no active ingredients). Three groups of dogs were treated topically with the metaflumizone plus amitraz formulation (150mg of each of metaflumizone and amitraz/ml), at volumes providing doses of 10, 20 and 40mgeachactive/kg. The final group was treated with a commercial spot-on providing 6.7mgfipronil/kg. All treatments were applied to the skin at a single spot between the scapulae on Day 0. Dogs were infested with 50 adult brown dog ticks (Rhipicephalus sanguineus) on each of Days -2, 5, 12, 19, 26, 33 and 40, and with 100 cat fleas (Ctenocephalides felis felis) on Days -1, 6, 13, 20, 27, 34 and 41. Dogs were examined and parasites "finger counted" on Day 1 to estimate knock down efficacy, and all animals were comb counted to determine the numbers of viable fleas and ticks on Days 7, 14, 21, 28, 35 and 42. There were no significant differences in parasite counts between the nontreated control and the placebo-treated control groups for either fleas or ticks (P>0.05) except for very slight reductions on Day 7 for fleas and Day 14 for ticks, demonstrating that the formulation excipients had no activity. The qualitative finger counts on Day 1 indicated that all of the insecticidal treatments resulted in a noticeable reduction in flea and tick numbers within 1 day of treatment. All of the metaflumizone and amitraz treatments and fipronil resulted in significantly lower flea and tick numbers relative to nontreated controls on all posttreatment count days (P<0.05). For the metaflumizone plus amitraz treatments, mean flea and tick counts for the 10mg/kg dose were significantly higher than those for the 20mg/kg dose (P<0.05) from Day 21 on. There was no significant advantage provided by the 40mg/kg dose over the 20mg dose throughout the entire study (P>0.05). The two higher metaflumizone plus amitraz doses provided >95% control of fleas and >90% control of ticks for at least 35 days after treatment, and this level of control was similar to that of the commercial fipronil product. The 20mg/kg dose was selected as the minimum commercial dose rate to provide effective flea and tick control for at least 1 month following a single treatment.     

Effects of lufenuron treatment in cats on the establishment and course of Microsporum canis infection following exposure to infected cats

OBJECTIVE: To determine effects of lufenuron treatment in cats on the establishment and course of Microsporum canis infection following exposure to infected cats. DESIGN: Experimental trial. ANIMALS: 24 healthy juvenile domestic shorthair cats. PROCEDURE: 8 cats were given lufenuron PO (133 mg/cat/mo, equivalent to a dose of 100 to 130 mg/kg [45 to 59 mg/lb] at the beginning of the study and 25 to 35 mg/kg [11 to 16 mg/lb] at the end of the study), and 8 were given lufenuron SC (40 mg every 6 months). The remaining 8 were used as untreated control cats. After 4 months, cats were challenged by the introduction of cats with mild, experimentally induced M canis infection into the rooms where cats were housed. Extent of resulting infections in the na?ve cats was monitored for 22 weeks by physical examination and fungal culture. RESULTS: All lufenuron-treated and control cats became infected with M canis. Cats treated with lufenuron had significantly lower infection scores, compared with control cats, during the early weeks following exposure, and there was a more prolonged initial progression phase of the infection. Once infections reached peak intensity, they resolved over similar periods in lufenuron-treated and control cats. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that oral or SC administration of lufenuron to cats, at the dosages used and under the conditions of this study, did not prevent establishment of dermatophytosis following exposure to infected cats. Infection was established more slowly among cats treated with lufenuron, but once established, infection resolved in approximately the same amount of time in lufenuron-treated as in control cats.     

Dose selection of selamectin for efficacy against adult fleas (Ctenocephalides felis felis) on dogs and cats

Selamectin, a novel avermectin, was evaluated in two controlled studies (one in Beagles, one in domestic shorthaired cats) to determine an appropriate topical dose for efficacy against adult Ctenocephalides felis felis (C. felis) fleas on dogs and cats for 1 month. For each study, animals were allocated randomly to four treatments. One treatment consisted of the inert formulation ingredients (vehicle) administered as a negative control, and the other three treatments consisted of a single topical dosage of 3, 6, or 9mgkg(-1) of selamectin. In each study, selamectin was administered as a topical dose applied to the skin in a single spot at the base of the neck in front of the scapulae. Dogs and cats were infested with 100 viable unfed C. felis (50 males and 50 females) on days 4, 11, 18, and 27. Seventy-two hours (+/-2h) after each infestation, on days 7, 14, 21, and 30, a comb count to determine the number of viable fleas present on each animal was performed. Efficacy of selamectin on day 30 was used to select an appropriate dose. For dogs and cats, percentage reductions in geometric mean flea comb counts for the three selamectin treatments ranged from 94. 6 to 100% on days 7, 14, and 21, compared with the negative-control treatment. On day 30, reductions in flea comb counts were 81.5, 94.7, and 90.8% for dogs, and 79.8, 98.0, and 96.2% for cats treated with selamectin at 3, 6, or 9mgkg(-1), respectively. For day 30 flea comb counts for dogs and cats, analysis of variance showed that the three selamectin treatments resulted in significantly (P< or =0.05) lower counts than did the negative-control treatment. For dogs and cats, geometric mean flea counts for selamectin administered at a dosage of 3mgkg(-1) were significantly (P< or =0.05) higher than those for the 6 and 9mgkg(-1) treatment dosages combined. There were no significant differences in flea counts between the 6 and 9mgkg(-1) treatments. This analysis was confirmed by linear-plateau modeling. Thus, the optimal dose of selamectin for efficacy against adult fleas for both dogs and cats, as estimated by the turning point (plateau) in the dose response curve, was 6mgkg(-1).