Monepantel in the control of Haemonchus spp. and Trichostrongylus spp. and possible side effects of treatment in naturally infected sheep

Sheep breeding represents an important economic source in many countries; however, anthelmintic resistance is an important limiting factor for sheep breeding development, due to its effects in animal performance. Monepantel is an active principle derived from an amino-acetonitrile class, with proven efficacy in the control of gastrointestinal parasites. However, the side effects associated to this treatment remain unknown. Thus, the aim of this study was to evaluate the effect of anthelmintic treatment with monepantel as well as evaluate the hepatic function, proteic and lipid metabolism, and antioxidant/oxidant levels in serum of naturally infected sheep with helminths. Sixteen naturally infected animals were used; all subjects had similar parasitic degree (determined by McMaster technique) on day 0. The animals were divided in two groups (A and B) with eight animals each. Group A did not receive any treatment (control group), while group B received a single dose of monepantel (2.5 mg/kg) on day 0 of the experiment. Fecal exams performed on days 4 and 8 post-treatment (PT) revealed a significant reduction (p < 0.05) in the number of eggs per gram of feces (EPG) in the group B where animals were treated with monepantel. On days 4 and 8 PT, seric reactive oxygen species (ROS) and superoxide dismutase (SOD) activity increased (p < 0.05), while the catalase (CAT) activity in serum decreased (p < 0.05) within the group B. Based on these results, we can conclude that monepantel is very likely to be a safe drug, effective in the control of helminths, and possesses direct effect on SOD activation in sheep.