Evaluación de la resistencia a lactonas macrocíclicas en nematodos gastrointestinales de equinos y el potencial de fitobióticos como alternativa complementaria

Given the growing resistance of equine parasites to macrocyclic lactones, there is an urgent need to evaluate phytobiotics as a natural, effective, and sustainable alternative. The objective of this study was to conduct a systematic review of the resistance of equine gastrointestinal nematodes to macrocyclic lactones and to determine the efficacy of phytobiotics as a complementary alternative for their control. A descriptive-analytical systematic review was conducted, selecting 20 high-impact scientific articles (2023–2026). After identifying and screening studies in indexed databases, key variables regarding anthelmintic resistance and phytobiotics were extracted and analyzed comparatively to propose strategies for sustainable equine parasite control. Global resistance (>70%) to macrocyclic lactones in horses reduces therapeutic efficacy to below 95% and shortens the time to egg reappearance to 5 weeks, due to mechanisms such as the overexpression of efflux glycoproteins. As an alternative, phytobiotics (tannins, saponins) inhibit the parasitic cycle in vitro by up to 100% and reduce the burden in vivo by 30–60%, while also improving intestinal health. The growing global resistance to macrocyclic lactones, due to intensive use, compromises traditional equine parasite control. Phytobiotics are emerging as an effective complementary alternative for managing the nematode life cycle and boosting immunity; their integration with rational drug regimens is key to sustainable management