Application of bacteriophages in the prevention and control of bacterial infectious diseases in animals.

The global spread of antimicrobial resistance (AMR) has intensified the search for alternatives to conventional antibiotics in animal production systems. Bacteriophages can be engineered beyond narrow-spectrum antibacterial agents into multifunctional biological platforms that integrate direct killing, immune modulation, and antigen delivery. We summarize recent advances across livestock, poultry, and aquaculture, delineating mechanistic distinctions between lytic phage therapy, phage display-derived interventions, and engineered platforms including CRISPR-Cas-enabled theranostic systems. However, as detailed below, most evidence remains preclinical, and translational gaps are substantial. Unlike prior descriptive reviews, we analyze translational bottlenecks-host range constraints, pharmacokinetic limitations, regulatory fragmentation-and assess the existing research evidence for claimed advantages such as microbiota preservation and biofilm penetration while upfront acknowledging inconsistent experimental outcomes and inherent application limitations behind these beneficial effects. We conclude that realizing phages' therapeutic potential in veterinary medicine requires coordinated progress in synthetic biology, scalable manufacturing, and regulatory harmonization within a One Health framework.