Captive breeding of specialty animals represents an overlooked yet critical reservoir for spreading antibiotic resistance genes

Driven by wildlife conservation and economic demands, captive breeding has expanded globally, intensifying wildlife-human interactions. In specialty animal breeding, particularly for species with short domestication histories and underdeveloped breeding protocols, clinically important antibiotics are commonly misused, posing potential ecological and health risks that remain largely unexplored. We collected fecal samples from three groups of musk deer (Moschus berezovskii): those exposed to clinically important antibiotics, those not exposed for six months, and wild musk deer, and analyzed their microbiomes and resistomes using metagenomic and culture-based methods. We found that captivity significantly expanded and reshaped the fecal resistome of musk deer. The antibiotic-exposed musk deer harbored a significantly higher diversity and abundance of antibiotic resistance genes (ARGs) compared to those non-exposed to antibiotics and wild deer. We observed a higher abundance of clinically important ARGs within Enterobacteriaceae in fecal samples of captive musk deer. This observation was further supported by the antibiotic susceptibility profiles of 124 Escherichia coli strains isolated from antibiotic-exposed musk deer. Seven identical mobile genetic element-associated ARGs were detected in distinct bacterial hosts across fecal samples from musk deer and farm workers, indicating potential conjugative transfer between the two groups. Our results suggest that captive breeding of specialty animals is an overlooked but significant reservoir for disseminating clinically important ARGs, and underscore the transmission risk at the animal-human interface.