Treatment and control of bovine sarcoptic and psoroptic mange infestation with ivermectin long-acting injectable (IVOMEC(®) GOLD).

The efficacy of ivermectin long-acting injection (IVM LAI, IVOMEC® GOLD, Merial; 3.15 % ivermectin w/v) formulation was evaluated in cattle with induced Sarcoptes scabiei var. bovis or Psoroptes ovis infestations. A total of 64 cattle were included in this series of four studies, with 16 animals per study. Approximately, 8 weeks following initial induced mite infestation, cattle were allocated to treatment groups based on decreasing pre-treatment bodyweights. Treatments (saline (control) or IVM LAI (630 mcg ivermectin/kg bodyweight) at 1 mL/50 kg bodyweight) were administered by a single subcutaneous injection in front of the right shoulder on Day 0. Skin scrapings were collected prior to treatment and at approximately weekly intervals for 8 weeks thereafter to establish live mite counts. Character and extent of skin lesions were evaluated at each sampling. Animals were weighed before treatment and at the end of the studies. Mite counts of the IVM LAI-treated animals were significantly (p < 0.05) lower than those of the controls in all four studies at all occasions post-treatment. In the two Sarcoptes studies, IVM LAI-treated cattle were free of mites at 14 days after treatment and in the Psoroptes studies at 13 or 28 days post-treatment. All IVM LAI-treated cattle remained free of mites to the end of the studies while all control animals remained infested. Mange lesions of the IVM LAI-treated animals improved significantly (p < 0.05) compared to those of the controls from Day 21 (Sarcoptes studies) and from Days 28 or 34 (Psoroptes studies). In all studies, mean weight gain over the 8 week post-treatment period was significantly (p < 0.05) higher for the IVM LAI-treated animals than for the controls: Sarcoptes studies, 64.1 and 68.6 kg vs. 46.9 and 48.6 kg, respectively; Psoroptes studies, 43.0 and 43.4 kg vs. 20.8 and 34.9 kg, respectively. All animals accepted the treatment well, and no treatment-related health problems and adverse events were observed throughout the studies. These studies demonstrated the high efficacy of IVOMEC® GOLD against sarcoptic and psoroptic mange in cattle.