Based on many previous studies, this study reviewed the effects of needle-free intradermal injection (NFI) on the prevention of the incidence of lesions at the injection site in pork from pigs vaccinated with the foot-and-mouth disease vaccine, the reduction of the vaccine dose, the stress-relief of vaccination, and the reduction of farm worker-related injuries. The vaccine and drugs injected with the NFI pass through the tissue and are widely dispersed along the path of least resistance, resulting in a vastly dispersed, spider-web-like distribution of the medication and absorbed quickly. In addition, since NFI is inoculated into the dermal layer where immune cells are abundantly distributed, even a small amount of vaccination shows an antibody-forming effect similar to that of the conventional needle intramuscular injection. NFI is a method suitable for animal welfare because the vaccine or drug is widely dispersed over the inoculation site and causes less pain or stress than the needle intramuscular injection. Use of NFI system for the vaccination and drug delivery improves work efficiency in farms and reduces the incidence of musculoskeletal disorders in farm workers. In the future, it is judged that in-depth studies are needed on the effect of improving productivity and reducing the dose of antibiotics through NFI.

This study compared the immune responses, stress relief and weight gains of needle or needle-free intramuscular and needle-free intradermal vaccination in pigs. When the same amount of a foot-and-mouth disease (FMD) vaccine was administered to pigs, antibody titers at 4 weeks after the 1st and 2nd FMD vaccination were not significantly different between the needle (IM-S) and needle-free (NM-P250) intramuscularly vaccinated groups, but the weight gain of NM-P250 was significantly increased compared to that of IM-S at 8 weeks after the 2nd FMD vaccination (p<0.05). In addition, serum cortisol concentrations of NM-P250 were considerably decreased compared to those of IM-S on the 5th and 7th day after the 1st and 2nd FMD vaccination (p<0.05). However, the antibody titers of IM-S vaccinated with 2 mL of FMD vaccine were significantly increased compared to those of the needle-free intradermal vaccinated group with 0.5 mL of FMD vaccine at 4 weeks after the 1st and 2nd FMD vaccination (p<0.05). In conclusion, the needle-free intramuscular injection for the FMD vaccination can be chosen for weight gain and stress relief in pigs.