Persistent activity of moxidectin long-acting injectable formulations against natural and experimentally enhanced populations of lice infesting cattle

Publication Type  Journal Article
Year of Publication  2004
Authors  Cleale, R. M.; Lloyd, J. E.; Smith, L. L.; Grubbs, M. A.; Grubbs, S. T.; Kumar, R.; Amodie, D. M.
Journal Title  Veterinary parasitology
Volume  120
Issue  3
Pages  215-227
Journal Date  Mar 25
Accession Number  44728
Key Words  Animals; Cattle ; Cattle Diseases ; Injections ; insecticide ; Least-Squares Analysis ; Lice/growth & development ; Lice Infestations/parasitology/prevention & control/veterinary ; Macrolides ; Random Allocation
Abstract  A study was conducted under a common protocol in Wisconsin and Wyoming, USA, to evaluate therapeutic and persistent efficacy of two long-acting injectable formulations of moxidectin against lice populations infesting cattle. At each site, 30 beef calves were blocked into groups of three based on naturally acquired Linognathus vituli populations, then randomly assigned to treatments within blocks. Treatments, injected subcutaneously into the proximal third of the ear on Day 0, included saline, a long-acting oil-based formulation containing 10% moxidectin given at the rate of 1 mg moxidectin/kg body weight (M10/1.0), or a long-acting oil-based formulation containing 15% moxidectin given at the rate of 0.75 mg moxidectin/kg b.w. (M15/0.75). Species of sucking and chewing lice were quantified on nine predilection sites before treatment, then 28, 63, 98, 133 and 168 days after treatment. During intervals between lice counts after Day 28, study animals from the three treatment groups were commingled for 32 days with two lice-free sentinels plus four to six seeder calves with infestations of both sucking and chewing lice. Following each 32-day commingling interval, seeder and sentinel animals were removed, and principal animals were sorted into pens by treatment. Lice were quantified on sentinel animals on the day of removal, and lice were quantified on principal study animals 3 days after removal of sentinel and seeders. Moxidectin was generally not efficacious against Bovicola bovis in the injectable formulations tested, whereas Haematopinus eurysternus infestations were inadequate to judge product effectiveness. Based on geometric means, both M15/0.75 and M10/1.0 provided statistically significant therapeutic efficacy against existing infestations of L. vituli and Solenopotes capillatus (100% efficacy on Day 28), and provided persistent protection against reinfestation with L. vituli and S. capillatus (efficacy >97%) for at least 133 days following treatment.
Notes  LR: 20041117; JID: 7602745; 0 (Insecticides); 0 (Macrolides); 51570-36-6 (milbemycin); 2004/01/23 [received]; ppublish0304-4017 Journal
  
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