Nanotechnology has revolutionized veterinary diagnostics by enabling rapid, sensitive, and cost-effective detection of animal diseases. Traditional diagnostic methods, while effective, often suffer from limitations such as lengthy processing times, reduced sensitivity, and reliance on sophisticated laboratory setups. Nanoparticles, owing to their unique physicochemical properties including high surface area, optical tunability, and functionalization capabilities have emerged as powerful tools in veterinary diagnostics. This chapter explores the various types of nanoparticles employed in veterinary diagnostics, including gold nanoparticles (AuNPs), quantum dots (QDs), magnetic nanoparticles (MNPs), polymeric nanoparticles (PNPs), and carbon-based nanomaterials. These nanomaterials function through diverse mechanisms such as optical detection, magnetic separation, electrochemical sensing, and enzyme-mimetic activity, enabling highly specific and efficient disease identification. The application of nanoparticle-based diagnostic platforms has significantly enhanced the detection of infectious diseases, zoonotic pathogens, and biomarkers indicative of animal health. Their integration into biosensors, lateral flow assays, and point-of-care devices has improved diagnostic accessibility, particularly in remote and resource-limited settings. However, challenges related to cost, toxicity, stability, and regulatory approval remains barriers to widespread adoption. Future advancements in nanoparticle synthesis, functionalization, and artificial intelligence-driven diagnostics hold promise for overcoming these limitations. As research progresses, nanoparticle-based veterinary diagnostics are expected to play a pivotal role in improving disease surveillance, animal healthcare, and global biosecurity.