Reframing veterinary vaccine quality control: Integrating alternative assays within lifecycle-based regulatory frameworks.

Veterinary vaccine quality assurance has traditionally relied on animal-based potency, safety, and efficacy tests, including challenge protection and in vivo titration assays. Although historically regarded as regulatory gold standards, these methods are increasingly constrained by ethical considerations, high costs, limited throughput, and prolonged timelines. In response, strong scientific and regulatory momentum now supports alternative approaches that reduce or replace animal use while maintaining confidence in vaccine performance. This review critically examines the current landscape of non-animal and reduced-animal methodologies for veterinary vaccine evaluation within the 3Rs framework (Replacement, Reduction, and Refinement). We synthesize advances across five methodological domains: molecular and genetic quantification (including qPCR, digital PCR, and DIVA strategies); cell-based and in vitro functional potency assays; immunochemical and point-of-care platforms; physicochemical and analytical characterization; and systems-level immunological and multi-omics approaches. For each category, we discuss scientific principles, analytical performance, validation requirements, and regulatory acceptance, with emphasis on alignment with WOAH and VICH guidance. Practical challenges related to assay standardization, reference materials, infrastructure, and inter-laboratory reproducibility are addressed. Species-specific case studies spanning livestock, companion animal, and poultry vaccines including foot-and-mouth disease, lumpy skin disease, rabies, and avian influenza illustrate how integrated, weight-of-evidence strategies support batch release, consistency testing, and post-licensure surveillance. Collectively, the evidence supports a paradigm shift toward data-rich, mechanism-informed quality-control frameworks that enhance efficiency, ethical compliance, and regulatory confidence in veterinary vaccine evaluation.