Evaluation of the safety of spinosad and milbemycin 5-oxime orally administered to Collies with the MDR1 gene mutation.

OBJECTIVE: To determine whether signs of avermectin (AVM)-milbemycin (MB) toxicosis would be evident in AVM-MB-sensitive Collies after treatment with an experimental formulation of spinosad alone or spinosad combined with MB 5-oxime (MBO) at doses up to 5 and 10 times the MBO maximum label dose. ANIMALS: 20 adult Collies homozygous or heterozygous for the MDR1 gene mutation that had signs of toxicosis after oral administration of ivermectin. PROCEDURES: On the basis of AVM-MB sensitivity score, each dog was assigned in a randomized block design to 1 of 5 treatment groups (control group, 300 mg of spinosad/kg [5 times maximum label dose], 180 mg of spinosad/kg with 3 mg of MBO/kg [3 times maximum MBO label dose], 300 mg of spinosad/kg with 5 mg of MBO/kg, and 300 mg of spinosad/kg with 10 mg of MBO/kg). Treatments were administered orally as a sequence of single doses during 5 consecutive days. After a 28-day washout period, treatment sequences were repeated. Posttreatment observation and scoring by blinded observers were conducted to specifically include neurologic abnormalities typical of AVM-MB toxicosis, such as signs of depression, ataxia, mydriasis, and hypersalivation. RESULTS: No signs of AVM-MB toxicosis were attributed to treatment in any dog during the study. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that oral administration of spinosad at 300 mg/kg alone or in combination with MBO at doses up to 10 mg/kg did not cause signs of AVM-MB toxicosis in AVM-MB-sensitive dogs with the MDR1 gene mutation.

Therapeutic and persistent efficacy of spinosad applied as a pour-on or a topical spray against natural infestations of chewing and sucking lice on cattle.

Studies were conducted in Wisconsin and Illinois, USA, to assess and compare the therapeutic and persistent efficacy of spinosad when applied as either a pour-on or topical spray and compared with cyfluthrin pour-on and coumaphos topical spray for controlling natural infestations of chewing (Bovicola bovis) and sucking (Linognathus vituli, Solenopotes capillatus and Haematopinus eurysternus) lice on cattle. Thirty-five animals at each trial site were blocked according to pre-treatment lice counts and randomly allocated to one of five treatment groups: single treatments of spinosad (25 g/L), diluted with water to 0.04% active ingredient and applied as a whole-body topical spray; spinosad (25 g/L) applied as a neat pour-on at 2 mg/kg body weight; Co-Ral Emulsifiable Livestock Insecticide (5.8% coumaphos), diluted to 0.03% active ingredient and applied as a whole-body topical spray; CyLence Pour-on Insecticide (1% cyfluthrin), applied as a neat pour-on at the manufacturer's recommended use rate for lice; and untreated control. Both spinosad treatments and cyfluthrin provided > or =96% control of B. bovis for up to 7 weeks, whereas the efficacy of coumaphos dropped to <90% after week 5 at one site. Spinosad spray had the best therapeutic and residual control of all treatments against L. vituli, > or =98% for at least 5 weeks at both sites, compared with 3 weeks for coumaphos at one site. Spinosad and coumaphos sprays provided 100% control of S. capillatus for at least 8 weeks compared with > or =97% control for spinosad and cyfluthrin pour-on treatments over the same interval. While H. eurysternus burden was low and limited to one study site, all four treatments provided 100% control for at least 6 weeks. These studies showed that topically applied spinosad provided a high degree of therapeutic and residual control against both sucking and chewing lice.

Effects of dermal application of 10.0% imidacloprid-0.08% ivermectin in ivermectin-sensitive Collies.

OBJECTIVE: To evaluate the safety of dermal application of 10.0% imidacloprid-0.08% ivermectin in ivermectin-sensitive Collies at dose rates of 3 to 5 times the proposed maximum therapeutic dose. ANIMALS: 15 Collies (5 males and 10 females) that were confirmed as ivermectin-sensitive dogs. PROCEDURE: Dogs were assigned to 3 treatment groups (control, 3X, or 5X group) in a randomized block design on the basis of the maximal ivermectin-sensitivity score obtained during preliminary screening. Dogs in groups 3X and 5X were treated at 3 and 5 times the maximum label dose, respectively. Control dogs received an application of an equal volume of a nonmedicated solution. Observation and scoring on all days were conducted to specifically include neurologic signs typical of ivermectin toxicosis, including lethargy, ataxia, abnormal mydriasis, and abnormal salivation. RESULTS: None of the dogs had clinical abnormalities during the study period. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of results of this study indicates that dermal application of 10.0% imidacloprid-0.08% ivermectin is safe for use in ivermectin-sensitive Collies at dose rates of 3 or 5 times the proposed maximum therapeutic dose.

Field efficacy of ivermectin plus praziquantel oral paste against naturally acquired gastrointestinal nematodes and cestodes of horses in North America and Europe.

The efficacy of an oral formulation of ivermectin plus praziquantel in the reduction of nematode and cestode egg counts in horses was assessed in 273 horses under field conditions at 15 sites in North America (n = 6) and Europe (n = 9). Horses were confirmed by fecal examination to have natural infections of strongyles (100%) and tapeworms (76%). Replicates of four horses were formed at each site, and in each replicate three animals received ivermectin (0.2 mg/kg body weight) plus praziquantel (1 mg/kg body weight) oral paste and one animal remained untreated or received vehicle paste. Fecal samples were collected for fecal nematode and cestode egg counting before and 7, 8, 9, 14, 15, and 16 days after treatment. Horses treated with ivermectin plus praziquantel oral paste had significantly (P <.01) lower posttreatment strongylid and cestode egg counts (reductions of 98% or more) than controls. Combined site analyses revealed that 95% or 96% of the horses positive for cestode eggs before treatment that were treated with ivermectin plus praziquantel were negative for cestode eggs at each posttreatment fecal examination. No adverse reactions attributable to ivermectin plus praziquantel oral paste treatments were observed. The results of the studies demonstrated that ivermectin plus praziquantel paste was highly effective in reducing egg shedding by gastrointestinal nematodes and cestodes, and no adverse reactions were observed in horses treated under field conditions.

Antiparasitic activity of an ivermectin and praziquantel combination paste in horses.

Modern anthelmintic use in horses has decreased the prevalence of the large strongyles, which has in turn shifted the focus of parasitologists to the pathogenic importance of the small strongyles, tapeworms, and other parasites. These studies show that a combination product containing ivermectin and praziquantel allowed efficacious treatment of horses for nematode, cestode, and bot infections. The use of this combination product may be of special benefit to horses that are mainly kept outdoors and on grazing pastures.

Safety of fluralaner, a novel systemic antiparasitic drug, in MDR1(-/-) Collies after oral administration.

BACKGROUND: Fluralaner is a novel systemic ectoparasiticide for dogs providing long-acting flea- and tick-control after a single oral dose. This study investigated the safety of oral administration of fluralaner at 3 times the highest expected clinical dose to Multi Drug Resistance Protein 1 (MDR1(-/-)) gene defect Collies. METHODS: Sixteen Collies homozygous for the MDR1 deletion mutation were included in the study. Eight Collies received fluralaner chewable tablets once at a dose of 168 mg/kg; eight sham dosed Collies served as controls. All Collies were clinically observed until 28 days following treatment. RESULTS: No adverse events were observed subsequent to fluralaner treatment of MDR1(-/-) Collies at three times the highest expected clinical dose. CONCLUSIONS: Fluralaner chewable tablets are well tolerated in MDR1(-/-) Collies following oral administration.