Ivermectin excretion in stools from injected and orally treated sows: a pilot study

Ivermectin is an anthelmintic drug belonging to the macrocyclic lactones class. It has a wide spectrum of action against endoparasite and ectoparasites. In Italy ivermectin is authorized in medicinal products registered for use in various animal species, including bovines, goats, equines, dogs, cats, sheep, and swine. It is commercially available in several formulations from injectable to edible pastes and tablets [1]. In swine farming, ivermectin is mainly used in breeding animals (sows and barrows) because of its long withdrawal period. This study aimed to assess ivermectin residue production in feces following injectable and oral treatments within a framework of environmental impact. Sampled sows from two swine farms in Emilia Romagna received either injectable or oral ivermectin treatment (1 ml/50 kg b.w.). Fecal samples were collected before treatment (t0), one day after treatment (t1) and ten days post-treatment (t10). Stools were collected from the rectal ampoule of a total of 70 sows and analyzed through LC/MS/MS with an adapted method from Carrillo Heredero et al [2]. Following treatment, orally treated sows exhibited higher median ivermectin concentrations at t1 (996.07 PPB) compared to injected sows (13.10 PPB). Conversely, at t10, injected sows showed higher concentrations (70.06 PPB) compared to orally treated sows (11.50 PPB). Notably, the oral treatment regimen spans several days, in contrast to the single administration characteristic of injectable treatment protocols. Significant differences in ivermectin quantities were observed between the two treatments at all time points (t0 p<0.01, t1 p<0.0001, t10 p<0.001). The oral treatment regimen resulted in a notable and statistically significant elevation in ivermectin levels between t0 and t1 (p<0.0001), while no discernible variance was observed with injectable treatments. This discrepancy may be attributed to the comparatively delayed distribution to the gastrointestinal tract associated with the injectable administration route. In an environmental residue-focused context, our findings highlight substantial differences between oral and injectable ivermectin treatments. Giving its high resistance in the environment and proven toxicity to non-target species, these disparities, both quantitative and in long-term excretion patterns, underscore the importance of considering administration routes in managing ivermectin residues in swine farming environments. REFERENCES 1. Prontuario dei medicinali veterinari - Banca dati online dei riassunti delle caratteristiche dei prodotti medicinali veterinary. Available online: https://www.vetinfo.it/j6_prontuario/public/ (accessed on 8 March 2024). 2. Carrillo Heredero, A.M.; Segato, G.; Menotta, S.; Faggionato, E.; Vismarra, A.; Genchi, M.; Bertini, S. A New Method for Ivermectin Detection and Quantification through HPLC in Organic Matter (Feed, Soil, and Water). J Anal Methods Chem 2023, 2023, 1–7, doi:10.1155/2023/6924263.