The role of dogs and cats as reservoirs of antimicrobial resistance: A molecular and epidemiological review with focus on Southeast Asian context

Antimicrobial resistance (AMR) is an increasingly complex global threat that transcends the boundaries of the human health sector. Within the One Health framework, companion animals such as dogs and cats are receiving increased attention due to their close proximity to humans and their potential role as reservoirs of resistant bacteria. Intense interactions in domestic environments, antibiotic exposure in veterinary clinical practice, and linkages with environmental factors make companion animals an integral part of the AMR epidemiological network. This review aims to comprehensively examine the role of dogs and cats as reservoirs of antimicrobial resistance, with emphasis on molecular characterization of resistance genes and identification of environmental risk factors that contribute to their dissemination. This article discusses key findings related to the most frequently reported resistance genes in commensal and pathogenic bacteria from companion animals, including genes associated with resistance to β-lactams, tetracyclines, aminoglycosides, and fluoroquinolones. Furthermore, molecular mechanisms such as the involvement of mobile genetic elements and phylogenetic relatedness among isolates from animals and humans are analysed to assess the potential for cross-host transmission. Environmental risk factors, including antibiotic use practices, household sanitation, animal population density, and intensity of human-animal contact, are discussed as important determinants in maintaining and spreading antimicrobial resistance. These findings indicate that dogs and cats not only serve as passive hosts, but also as active components in the ecology of AMR. Overall, this review affirms the need to integrate companion animals into One Health-based surveillance strategies, control measures, and antimicrobial resistance policies to sustainably reduce public health risks.