苦参外用总生物碱溶液防治绵羊天然虱子侵染的田间有效性和安全性

Lice infestation is a common ectoparasitic condition in sheep and may cause pruritus, wool loss, skin damage, and impaired productivity. This study developed a topical total alkaloid solution from Sophora alopecuroides and evaluated its formulation characteristics, stability, dermal tolerance, field efficacy, and target-animal safety in sheep naturally infested with lice. Total alkaloids were extracted from S. alopecuroides seeds using single-factor experiments and orthogonal optimization. Dermal safety was assessed using Buehler sensitization testing in guinea pigs and skin irritation testing in rabbits. Clinical efficacy was evaluated after medicated bath treatment in naturally infested sheep. The optimized extraction procedure used 70% ethanol, an 8-fold solvent-to-material ratio, 0.1% cellulase, and three extractions of 120 min each. The optimized formulation contained 6.5% total alkaloids, 10.0% sodium dodecyl sulfate, and 8.0% ethanol. The preparation met predefined quality criteria and remained stable under stress, accelerated, and long-term storage conditions. No treatment-related sensitization or irritation was observed in laboratory animals. In sheep, lice reduction rates at D4 were 95.27%, 100%, 100%, and 100% in the low-dose, medium-dose, high-dose, and diazinon groups, respectively, and all treated groups reached 100% lice reduction at D17. No obvious hematological, biochemical, or histopathological safety signals were observed. These findings support the potential of this plant-derived topical preparation for managing natural lice infestation in sheep.