Repellency and efficacy of a 65% permethrin spot-on formulation for dogs against Aedes aegypti (Diptera: Culicidae) mosquitoes

A topically applied 65% permethrin spot-on (Defend EXspot Treatment for Dogs, Schering-Plough Animal Health) used for flea and tick control on dogs was evaluated for repellency and efficacy against the yellow fever mosquito, Aedes aegypti, a vector of canine filariasis. Six dogs were randomly assigned to receive a single application of 65% permethrin on Day 0 (n=3) or to remain untreated as controls (n=3). Dogs were anesthetized and exposed to 100 unfed, female mosquitoes in screened cages for 2 hours on Days -6, -4, -1, 0, 1, 7, 14, 21, and 28. Mosquito landing rates, engorgement rates, and mortality were determined for each mosquito challenge. Cages were thoroughly cleaned after each mosquito challenge. Treatment of dogs with 65% permethrin reduced the mosquito landing rates by 96.3% 6 hours after treatment and by 82.5% on Day 1. Mosquito mortality, relative to the control group, was 28.2% 6 hours after treatment, ranged from 84.0% to 90.9% through Day 21, and declined to 50.3% 28 days after treatment. Successful feeding by mosquitoes was significantly (P=.05) reduced on Days 1 through 28. The 65% permethrin spot-on treatment killed and repelled significantly (P =.05) more mosquitoes on treated dogs versus untreated dogs for 28 days after treatment.     

Efficacy of two 65 % permethrin spot-on formulations against canine infestations of Ctenocephalides felis and Rhipicephalus sanguineus

The efficacy of two formulations of a topically applied 65% permethrin spot-on for dogs (Defend EXspot Treatment for Dogs, Schering-Plough Animal Health Corp.) was evaluated against experimental infestations of the cat flea, Ctenocephalides felis, and the brown dog tick, Rhipicephalus sanguineus. Thirty dogs were randomly allocated to treatment with 65 % permethrin in diethylene glycol monomethyl ether (original formulation), 65 % permethrin in propylene glycol monomethyl ether (test formulation), or to an untreated control group. Dogs assigned to treatment with a permethrin formulation received either 1 or 2 ml of the formulation in accordance with label directions on Day 0. One hundred unfed, adult cat fleas and 50 unfed, adult ticks were placed on each dog on Days -1, 5, 12, 19, 26, 33, and 40. Live fleas and ticks were counted on each dog on Days 2, 7, 14, 21, 28, 35, and 42. Treatment of dogs with either formulation of 65 % permethrin significantly (P <.05) reduced the number of live fleas and ticks from Days 2 through 42. No statistical differences were noted between the formulations regarding efficacy against C. felis or R. sanguineus.     

Efficacy of two 65% permethrin spot-on formulations against induced infestations of Ctenocephalides felis (Insecta: Siphonaptera) and Amblyomma americanum (Acari: Ixodidae) on beagles

The efficacy of two formulations of a topically applied 65% permethrin spot-on (Defend Exspot Treatment for Dogs, Schering-Plough Animal Health) was evaluated against experimental infestations of the cat flea Ctenocephalides felis and the lone star tick Amblyomma americanum in dogs. Eighteen dogs were randomly assigned to treatment with 65% permethrin in either diethylene glycol monomethyl ether (DGME; original formulation) or propylene glycol monomethyl ether (PGME) or to be untreated as a control. Treated dogs received either 1 (body weight < 15 kg) or 2 ml (body weight > or =15 kg) of the assigned formulation on Day 0. One hundred unfed, adult C. felis were placed on each dog on Days -6, -1, 4, 11, 18, 25, and 32. Fifty unfed, adult ticks were placed on each dog on Days -1, 3, 9, 16, 23, and 30. Live fleas and ticks were counted and removed on Days 3, 7, 14, 21, and 28. Treatment of dogs with the 65% permethrin in DGME reduced flea numbers by 90.4% to 99.9% from Days 3 through 21 (P < or =.05) and by 48.2% 28 days after treatment. Treatment of dogs with 65% permethrin in PGME reduced flea numbers by 93.7% to 99.7% from Days 3 through 28 and by 78.4% 35 days after treatment (P < or =.05). Treatment with 65% permethrin in DGME reduced tick numbers by 90% or more only on Day 7, whereas treatment with 65% permethrin in PGME reduced the number of live ticks by 90%or more on Days 7 and 14 and approached 90%(87.9%) on Day 21. Efficacy against fleas and ticks for the PGME formulation was significantly better (P < or =.05) than for the DGME formulation on Day 28. Findings in this study indicate that both the DGME and PGME formulations of 65% permethrin performed well in reducing numbers of live C. felis and A. americanum on laboratory beagles; however, the PGME formulation was effective approximately 1 to 2 weeks longer than the DGME formulation.     

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.     

Efficacy of dinotefuran, permethrin and pyriproxyfen combination spot-on against Aedes aegypti mosquitoes on dogs

A spot-on formulation combining permethrin, dinotefuran and pyriproxyfen (Vectra 3D? spot-on solution for dogs - one 10-25kg pipette contains 196mg dinotefuran, 1429mg permethrin and 17mg pyriproxyfen) was evaluated in adult Beagle dogs in a study designed to measure its efficacy to control Aedes aegypti (anti-feeding effect and mortality effect). The trial was performed according to Animal Welfare and Good Clinical Practice. Twelve dogs (five males and seven female, >3 years old, weighing 8.8-13.0kg) were randomly allocated to treatment groups on pre-treatment mosquito counts: six dogs served as untreated controls, and six dogs were treated with the test formulation. Treatment consisted of applying a combination formulation to deliver at least 46.6mgkg(-1) permethrin, 6.40mgkg(-1) dinotefuran and 0.57mgkg(-1) pyriproxyfen. The combination is designed to control fleas, ticks, sand flies and mosquitoes. Each dog was infested with approximately 100 adult unfed A. aegypti once before treatment (day 6) then at 1, 7, 14, 21 and 28 days post-treatment. Counts and engorgement determination of dead and live mosquitoes were performed after 1h exposure period. In the treated group (group A), the repellency effect of the product based on engorgement status (anti-feeding effect), was 91.5%, 94%, 94.7%, 94% and 87% at 1, 7, 14, 21 and 28 days post-treatment. Mortality effect or insecticidal efficacy calculated at the end of the 1-h exposure was almost identical when calculated 24h after the 1-h exposure and remained above 93% until the end of the in-life phase. No adverse events were observed following treatment, including observations conducted 2, 4 and 24h after the last dog was treated.     

Effective treatment and control of biting lice, Felicola subrostratus (Nitzsch in Burmeister, 1838), on cats using fipronil formulations

The efficacy of 0.25% fipronil spray (Frontline Spray, Merial), 10% fipronil spot-on (Frontline Spot-on for Cats, Merial) and 10% fipronil/12% (S)-methoprene (Frontline Plus for Cats, Merial) against the biting louse Felicola subrostratus on cats was assessed and confirmed under laboratory conditions. A field study evaluated the efficacy of a single topical application of Frontline Spray, and spot-on against the parasite on cats. In the laboratory studies, animals were allocated based on pre-treatment louse counts to the treatment groups: (1) untreated control and (2) 10% fipronil spot-on in the exploratory study or (1) untreated control, (2) 0.25% fipronil spray, at 6 ml/kg; (3) 10% fipronil spot-on as per label and (4) 10% fipronil/12% (S)-methoprene as per label in the confirmation study. Cats in treatment groups 2-4 were treated twice topically on Days 0 and 28. No live F. subrostratus were found on cats treated with fipronil formulations at any post-treatment examination. The difference from controls was significant (P < 0.01) for each product at each examination. Based on whole body counts at Day 42, the efficacy of each product was determined to be 100%. In the field study, cats were allocated in strict order of presentation. Cats were randomly allocated to one of the three treatment groups: (1) propoxur collar (Bolfo, Bayer); (2) 0.25% fipronil spray, at 6 ml/kg and (3) 10% fipronil spot-on as per label. Cats were treated once topically on Day 0. Louse counts of cats treated with fipronil formulations were not different than those of cats receiving the propoxur collar. The efficacy was determined to be > 98% on Day 2 and 100% on Days 28 and 42 in all treatment groups. The results of these studies demonstrate that fipronil in topical formulations is effective for treatment and control of biting lice (F. subrostratus) infestations on cats.     

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.     

Efficacy of a combination of imidacloprid 10%/permethrin 50% versus fipronil 10%/(S)-methoprene 12%, against ticks in naturally infected dogs

Preventing tick bites is a fundamental step towards reducing the impact of tick-borne protozoal, bacterial and viral diseases (TBDs) in humans and animals. The aim of this study was to evaluate the efficacy of a combination of imidacloprid 10%/permethrin 50% and of fipronil 10%/S-methoprene 12% against ticks in naturally infected dogs and to assess methodological parameters to calculate drug efficacy on tick immature stages.

From July to August 2004, 45 privately owned dogs of various sexes, ages, breeds, coat length and habits were enrolled in a trial carried out in an area (radius approximately 50 km) in Southern Italy. Three homogeneous groups (both for dog population and tick population) were formed: 15 dogs treated with imidacloprid 10% and permethrin 50% spot-on (group A), 15 dogs treated with fipronil 10% and methoprene 12% spot-on (group B) and 15 untreated dogs (group C). The dogs in each group were then sub-grouped according to their age and weight. Two different treatments were administered (time 0 and +28 days) to groups A and B, and the dogs were checked weekly for tick infestation until day +56 post-treatment (p.t.). Twenty-four areas distributed on the whole body surface were examined for ticks at each follow-up, while only at time 0 and at day +56 p.t., ticks were collected from the dogs and identified.

For the immature stages a semi-quantitative method was adopted and the load of immature stages was evaluated and grouped into four classes up to day +56 p.t. when the mean number of immature ticks (MIT) for each infection class was evaluated.

All the adult ticks collected were identified as brown dog ticks (Rhipicephalus sanguineus). Immature stages were first compared at day +28 p.t.. The efficacy of both products used in groups A and B on adult ticks was high and generally very similar. Conversely, the efficacy of imidacloprid 10% and permethrin 50% against immatures was higher than that of fipronil 10% and methoprene 12% throughout the observation period with statistically significant differences (p < 0.05) at day +28 p.t. (i.e. group A = 98.52%, group B = 72.40%).

On the whole, in analysing the efficacy of both products against adult plus immature ticks, it was found that the combination of imidacloprid 10% and permethrin 50% was more effective than fipronil 10% and methoprene 12%, with the differences being statistically significant at day +28 p.t. (group A = 98.43%, group B = 77.56%).     

Evaluation of the efficacy of a topically administered combination of imidacloprid and permethrin against Phlebotomus perniciosus in dog

The phlebotomine sand fly Phlebotomus perniciosus is one of the main vectors of Leishmania infantum, responsible for human and canine leishmaniasis in the Mediterranean Basin. The objective of this study was to evaluate the repellent and insecticidal efficacy of imidacloprid 10% (w/v)/permethrin 50% (w/v) spot-on against sand flies (P. perniciosus) on dogs. The dogs used in this trial were laboratory-bred beagles: eight were impregnated with the solution (treated group), while the other eight were left untreated (control group). On day 0 the animals in the treatment group received 0.1 ml/kg body weight of the combination imidacloprid/permethrin spot-on. Dogs were exposed for 1h to about 100 female sand flies at weekly intervals for a period of 4 weeks, on day 1, 7, 14, 21, and 28 after applying the product. The repellency criterion was based on the feeding rate of sand flies in the treated compared to the untreated group. The insecticidal efficacy criterion was based on comparison of the survival rate of sand flies between the two groups. The product had an insecticidal efficacy on female sand flies of 53.2% (day 1), 49.4% (day 7), 15.1% (day 14), 13.2% (day 22), and 2.9% (day 29). The product showed a repellent effect of 97.7% (day 1), 96.3% (day 7), 96.5% (day 14), 92.7% (day 22), and 74.0% (day 29). Within the first week of application the insecticidal effect was significant; however it did not surpass 50%. On the other hand, the product showed a potent anti-feeding effect of over 90% during the first 3 weeks of this trial. Therefore, the application of this product every 3 weeks would be a good tool to significantly reduce sand fly bites over the period of transmission of vectorial diseases such as leishmaniasis and several arbovirosis such as Toscana virus.     

Efficacy of imidacloprid (8.8% w/w) plus permethrin (44% w/w) spot-on topical solution against Amblyomma americanum infesting dogs using a natural tick exposure model

This study evaluated the efficacy of an imidacloprid 8.8% w/w + permethrin 44% w/w spot-on topical solution (K9 Advantix, Bayer Animal Health) against Amblyomma americanum using a natural field exposure model. Sixteen beagles were divided into two groups of eight dogs each. One group of dogs was treated with K9 Advantix and the other group served as untreated controls. On day -1 and at 3, 7, 14, 21 and 28 days after treatment, the dogs were walked for 80 minutes in an A. americanum-infested habitat at the Konza Prairie Biological Station in Northeastern Kansas. Postexposure tick counts (efficacy evaluations) were conducted on each dog at 3 and 48 hours after exposure. At 3 days after treatment, the efficacy of K9 Advantix within 3 hours of natural tick exposure was 88.0% and declined slowly during the study. The 48-hour postexposure efficacy remained above 93.5% throughout the study.     

Prevention of sand fly attack by topical application of a permethrin/pyriproxyfen combination on dogs

Dogs are the primary domestic reservoir of Leishmania infantum, the parasite responsible for most cases of human visceral leishmaniasis. A strategy for the control of leishmaniasis would be to inhibit the sand fly bite. A study was designed to measure the prevention of the sand fly attack by spraying a combination of permethrin and pyriproxyfen on dogs artificially exposed to the vector of leishmaniasis. Eight dogs were individually challenged with 100 female sand flies for 1 hour on Days -7, 0, 7, 14, 21, and 28. Four dogs were randomly assigned to a control group and four dogs were treated with topically applied permethrin/pyriproxyfen on Day 0. After each exposure, sand flies were collected, counted, and scored as fed or unfed. Efficacy of the combination for prevention of feeding was based on the number of unfed sand flies (dead or alive). The combination of permethrin/pyriproxyfen demonstrated a significant (P <.05) repellent effect against Phlebotomus perniciosus bites as soon as it was sprayed on the dogs, and its repellent efficacy lasted at least for 28 days. The combination product provided significant (P <.05) knockdown activity against challenge with sand flies for 21 days in adult dogs and 14 days in puppies. These findings indicate that adult animals in endemic areas should be sprayed with the permethrin/pyriproxyfen product at 3- to 4-week intervals, and young dogs should be sprayed at approximately 2-week intervals, to prevent sand fly attack.     

Repellency and efficacy of 65% permethrin and selamectin spot-on formulations against Ixodes ricinus ticks on dogs

Two topically applied spot-on products used for flea and tick control on dogs, 65% permethrin (Defend EXspot Treatment for Dogs, Schering-Plough Animal Health Corp., Union, NJ) and selamectin (Revolution [United States] or Stronghold [Europe], Pfizer Animal Health, New York, NY), were evaluated for repellency and efficacy against Ixodes ricinus, the primary vector of Lyme disease in Europe. Eighteen dogs were evenly and randomly allocated to the following treatments: 1) 65% permethrin, 2) selamectin, 3) untreated control. Dogs were treated by topical application of the assigned product in accordance with product label directions on Day 0. At 7, 14, 21, 28, and 35 days after treatment, each dog was exposed for 2 hours to 50 unfed, adult ticks in a cage with a carpet that covered approximately 70% of the floor area. After the exposure period, dogs were removed from the cages and live and dead ticks were counted on the dogs and in the cages. The number of live ticks recovered was reduced by 90.3% to 99.5% for dogs treated with 65% permethrin (P <.0001 versus controls and selamectin), compared with 10.9% to 31.1% for dogs treated with selamectin (P >.05 versus controls). The repellency of 65% permethrin was 63.4% to 80.2% against I. ricinus ticks (P <.0001 versus controls, P <.0007 versus selamectin), compared with 0% to 10.9% repellency for selamectin (P >.05 versus controls).     

Treatment of dog thelaziosis caused by Thelazia callipaeda (Spirurida, Thelaziidae) using a topical formulation of imidacloprid 10% and moxidectin 2.5%

Canine thelaziosis caused by Thelazia callipaeda infects dogs, cats, foxes, rabbits, and humans resulting in conjunctivitis, pain and excessive lacrimation. T. callipaeda live in the eyes under the nictitating membrane and females release first stage larvae which are ingested by flies which act as intermediate hosts. Control of canine thelaziosis is currently based on the removal of nematodes directly from the eyes of affected dogs or on the local instillation of antiparasitic drugs. With the aim of evaluating the efficacy against T. callipaeda of an association of imidacloprid 10% and moxidectin 2.5% by spot-on formulation administered via dermal application, three groups of naturally infected animals were selected: i.e. group A (21 dogs) received a single dose of imidacloprid 10% and moxidectin 2.5% by spot-on; group B (21 dogs) received a single dose of imidacloprid 10% by spot-on and group C (20 dogs) were left untreated. The efficacy of treatments was established by eye inspection and parasite viability and vitality after 1, 5 and 9 days after animal treatments (groups A and B) and after 9 days only in untreated animals (group C). Imidacloprid 10% and moxidectin 2.5% in spot-on formulation showed to be effective with regards the control of dog thelaziosis within 5 (90.47%) to 9 (95.23%) days after treatment. Only one dog from group A presented nematodes after treatment. The presence of parasites in the eyes of dogs from groups B (imidacloprid 10%) and C confirm that the anthelmintic efficacy against T. callipaeda in animal from group A (imidacloprid 10% and moxidectin 2.5%) was most likely attributable to moxidectin 2.5%. The spot-on formulation containing imidacloprid 10% and moxidectin 2.5% is very easy to apply and helps overcome problems linked to the mechanical removal of parasites or to the restraining of the animals for the local instillation of drugs in the eyes.     

Effect of a pelleted supplement fed during and after omeprazole treatment on nonglandular gastric ulcer scores and gastric juice pH in horses

Gastric ulcers are common in horses. The purpose of this study was to test the effect of a commercially available supplement, SmartGut^® Ultra pellets (SmGU) on gastric ulcer scores and gastric juice pH after omeprazole treatment in stall‐confined horses. Eight Thoroughbred horses were studied in a 2‐period, 2‐treatment crossover design, where the SmGU (40 g, twice daily) was mixed in grain feed. Horses were stall‐confined and treated with the supplement or control for 6 weeks, consisting of 2 weeks (Days 1–14) omeprazole treatment, 2 weeks (Days 14–28) following discontinuation of omeprazole treatment, one week (Days 28–35) alternating feed deprivation to induce or worsen existing ulcers and a one week (Days 35–42) recovery period. Gastroscopy was performed and gastric juice pH measured on Days 0, 14, 28, 35 and 42. Gastric ulcer lesion number (NGN) and severity (NGS) scores were assigned to each horse by an investigator (F.M.A.) masked to treatment. On Day 0 before treatment, mean NGN and NGS scores and gastric juice pH were not different (P>0.05) between treatment groups. By Day 14, mean NGN and NGS scores decreased (P<0.05) in both treatment groups. By Days 28 and 35, mean NGN score significantly increased in the untreated control horses but not the SmGU‐treated horses. By Day 42, mean NGN and NGS scores were not different in either group and were significantly lower than Day 0. Mean gastric juice pH was higher in both groups on Day 14 as a result of omeprazole treatment when compared with other days. SmartGut^® Ultra supplement added to the feed prevented the worsening of gastric ulcer number 2 weeks after omeprazole treatment, without altering the gastric juice pH. Supplementation with SmGU might aid in protection of the nonglandular stomach from recurrence of ulcers after omeprazole treatment in stall‐confined horses undergoing intermittent feeding.     

Efficacy of a novel formulation of metaflumizone plus amitraz for the treatment of sarcoptic mange in dogs

A novel spot-on formulation containing metaflumizone plus amitraz (ProMeris/ProMeris Duo for Dogs, Fort Dodge Animal Health, Overland Park, KS) was evaluated for efficacy against sarcoptic mange mites in naturally infested dogs. Sixteen dogs were allocated to two equal groups and were housed individually. Eight of the dogs were treated topically with metaflumizone plus amitraz at the proposed minimum dose rate (20mg/kg of each of metaflumizone and amitraz, at a dose volume of 0.133ml/kg) on Days 0 and 28. The other eight were treated with metaflumizone plus amitraz at the proposed minimum dose rate on Days 0, 14, 28 and 42. To enumerate Sarcoptes scabiei mites, skin scrapings were taken on each of Days 2, 14, 28, 42 and 56. Clinical signs of mange and the extent of sarcoptic lesions were evaluated on each dog when scrapings were made. Evaluation of the efficacy of the treatment was based on the absence of mites supported by the absence of clinical signs associated with canine sarcoptic mange. Treatment with metaflumizone plus amitraz at the minimum proposed dose rate at monthly (two treatments) or two-weekly (four treatments) intervals resulted in a rapid reduction of mites and improved clinical signs. The overall cure rates at Day 56, based on zero mite counts and/or resolution of clinical signs were 75% and 83% of dogs for the monthly and two-weekly regimens, respectively.     

A comparison of persistent anthelmintic efficacy of topical formulations of doramectin, ivermectin, eprinomectin and moxidectin against naturally acquired nematode infections of beef calves.

Persistent anthelmintic efficacy of topical formulations (all at a dosage of 500 microg/kg) of doramectin (DOR), ivermectin (IVM), eprinomectin (EPR) and moxidectin (MOX), in comparison with untreated control cattle (CONT), was observed in stocker beef calves during a 112-day winter-spring grazing trial. Five groups of 15 calves per group were grazed on 15 separate 2 ha pastures following random assignment of animals to specific pastures and then to treatment groups. All of the 5 treatments were represented in each of the 15 pastures. All cattle were weighed on study Days 1, 0, 28, 56, 84, 111 and 112. Fecal samples for nematode egg counts were collected on Days 7, 0, at 7 day intervals through Day 56 and at 14 day intervals to Day 1 12. Pooled group fecal cultures for determining generic composition of nematode infections were prepared at 14 day intervals throughout the study. As based on fecal egg counts, anthelmintic activity of EPR and MOX was greater (p < 0.05) than values for IVM or CONT through Day 28. Activity of DOR was greater (p < 0.05) than that of IVM on Days 7 and 14 only. Although significance levels varied little among treated groups from Day 42 to the end of the study, egg counts and percent reduction values of EPR and MOX remained consistently lower numerically than egg counts and higher than reduction values respectively, of DOR and IVM through Day 70. From Day 70 on, IVM counts were numerically, but not significantly higher than values of CONT. Based on larval culture, Cooperia predominated from Day 0 through 28 and again from Days 70 to 98; Ostertagia was second in prevalence with highest percentages, which exceeded those of Cooperia, between Days 42 and 70. Bodyweights of all treated groups, with exception of IVM, were always significantly greater (p < 0.05) than weights of CONT. Weights of IVM were numerically greater, but not significantly greater than CONT only on Days 84 and 112. From Day 56 on, there were no significant differences between weights of DOR, EPR and MOX, however, numerical values for MOX were consistently higher than values for the other two. Final average total bodyweight gains were: 153.7 kg for MOX, 148.5 kg for EPR, 146.9 kg for DOR, 139.7 kg for IVM and 127.7 kg for CONT.     

Efficacy of a novel formulation of metaflumizone plus amitraz for the treatment of demodectic mange in dogs

A novel spot-on formulation containing metaflumizone plus amitraz (ProMeris/ProMeris Duo for Dogs, Fort Dodge Animal Health, Overland Park, KS) was evaluated for efficacy against demodectic mange mites in naturally infested dogs. Sixteen dogs were allocated to two equal groups and individually housed. Eight of the dogs were treated topically with metaflumizone plus amitraz at the proposed minimum dose rate (20mg/kg of each of metaflumizone and amitraz, 0.133ml/kg) on Days 0, 28, and 56. The other eight were treated with metaflumizone plus amitraz at the proposed minimum dose rate on Days 0, 14, 28, 42, 56, and 70. Mite numbers were estimated from skin scrapings taken on Days -3 to -1, 28, 56, and 84. Clinical signs of mange and the extent of demodectic lesions on each dog were evaluated when skin scrapings were conducted. Efficacy of the treatment was based on a reduction in mite numbers and an assessment of the clinical signs associated with canine demodectic mange. Treatment at monthly or two-weekly intervals for 3 months resulted in a rapid reduction in mite numbers (>94 and >99% for the monthly and two-weekly treatments, respectively) and an improvement in clinical signs. Success rates, based on zero mite counts in skin scrapings at Day 84 were 42.9 and 62.5% of dogs for the monthly and two-weekly regimens, respectively.     

Evaluation of 65% permethrin spot-on and deltamethrin-impregnated collars for canine Leishmania infantum infection prevention

During the 2004 and 2005 sand fly seasons, we evaluated the efficacy of a 65% spot-on solution of permethrin (Exspot, Schering & Plough) and deltamethrin-impregnated collar (Scalibor, Intervet) in reducing Leishmania infantum infection, in a canine leishmaniasis (CanL) endemic region (Liguria) in Italy. Immunofluorescent assay (IFA) revealed that three of 120 dogs (2.5%) treated with a 65% spot-on solution of permethrin, as three of 119 dogs (2.5%) treated with deltamethrin-impregnated collar have shown seroconversion after sand fly season. On the contrary, seroconversion was 15% in 188 untreated control dogs. Treatment reduced the risk of infection by 84%. The difference in treated dogs and control ones is highly significant (chi2 = 12.4; P = 0.0004). Our results show that treatment with 65% spot-on solution of permethrin and the deltamethrin-impregnated collar are effective in reducing the risk of acquiring L. infantum infection.     

Efficacy and safety of imidacloprid/moxidectin spot-on solution and fenbendazole in the treatment of dogs naturally infected with Angiostrongylus vasorum (Baillet, 1866)

A randomized, blinded, controlled multicentre field trial study was conducted to evaluate the efficacy and safety of imidacloprid 10%/moxidectin 2.5% spot-on solution and fenbendazole in treating dogs naturally infected with Angiostrongylus vasorum. Dogs were randomly treated either with a single dose of 0.1 ml/kg bodyweight of imidacloprid 10%/moxidectin 2.5% spot-on solution or with 25 mg/kg bodyweight fenbendazole per os for 20 days. The study period was 42 days with dogs being examined on days 0, 7 and 42. The primary efficacy parameter was the presence of L1 larvae in faecal samples evaluated by a Baermann test from three consecutive days. Thoracic radiographs performed on each visit were being taken as a paraclinical parameter to support the results of the Baermann test. Twenty-seven dogs in the imidacloprid/moxidectin group and 23 dogs in the fenbendazole group completed the study according to protocol. The efficacies of the two treatment protocols were 85.2% (imidacloprid/moxidectin) and 91.3% (fenbendazole) with no significant difference between treatment groups. On radiographic evaluation pulmonary parenchyma showed similar improvement in each group. No serious adverse effects to treatment were recorded: most of the minor adverse effects were gastrointestinal such as diarrhea (nine dogs), vomitus (eight dogs) and salivation (three dogs). In general, these adverse effects were of short duration (1-2 days) within the first few days after treatment start and required little or no treatment. This prospective study demonstrates that both treatment protocols used are efficacious under field conditions, that treatment of mildly to moderately infected dogs with either of these protocols is safe and yields an excellent prognosis for recovering from the infection.     

Efficacy of Fipronil (9.8% w/w) + (S)-Methoprene (8.8% w/w) and Imidacloprid (8.8% w/w) + Permethrin (44% w/w) against Dermacentor variabilis (American Dog Tick) on Dogs.

This study evaluated overall efficacy, percentage of dogs free of live ticks, retention of ticks, and efficacy against retained ticks of fipronil (9.8% w/w) + (S)-methoprene (8.8% w/w) and imidacloprid (8.8% w/w) + permethrin (44% w/w) spot-on topical solutions against Dermacentor variabilis infesting dogs. Fipronil + (S)-methoprene provided significantly (P less than .05) greater tick control compared with the control dogs for the entire 30-day study period. Conversely, the combination product of imidacloprid + permethrin demonstrated activity significantly (P less than .05) different from control dogs only up to day 23. Significantly (P less than .05) more dogs treated with fipronil + (S)-methoprene were free of live ticks compared with controls on days 3, 9, and 16. There was never a significant difference (P greater than .05) between control and imidacloprid + permethrin-treated dogs in numbers of dogs free of live ticks. After the initial 10-minute tick exposure, lower numbers of ticks were retained on the imidacloprid + permethrin-treated dogs than on the fipronil + (S)-methoprene-treated dogs. However, when evaluating the effectiveness of the acaricides on "retained ticks," it appears that while some of the ticks were rapidly knocked down on the imidacloprid + permethrin-treated dogs, efficacy against ticks still retained at 10 minutes was never greater than 50%.