Scanner photography: effective technique to investigate needle free device injection dispersion pattern

Vaccination, allowing to contain infections and to prevent health problems is a crucial strategic management tool in today's pig industry. However, it also represents a cost item and therefore condition of vaccine application must be optimized. In the recent years needle free injection devices (NFID) have utilized various techniques for transcutaneous vaccine injections. Among the benefits to be highlighted there are: no broken needles in the meat, reduced inter animal transmission of diseases, respect of animal welfare. In this paper a scanographic (scanner photography) technique will be illustrated, for analyzing and quantifying transport / pattern of penetration and dispersion of a vaccine administered by NFID in piglets focussing on macroscopical visual injection outcome. Conventional piglets of 5-20 kg lbw were vaccinated on the left side of the neck with NFID Valery® (Giordano Poultry Plast, Caraglio Cuneo, Italy) with black china ink spiked CIRCOVAC® (MERIAL, Lyon, France), 1 cc ink/100 cc of vaccine), according to datasheet (0.5 ml/piglet) and immediately underwent euthanasia. Freezing of hanged piglets was carried out (48 h, -20°C) and subsequently frozen cross-sectional slices were obtained (thickness about 1 cm). Images were acquired by means of an ordinary flatbed scanner protected by a glass platen (hp, Palo Alto-CA, USA). Mechanism of liquid jet injectors relies on the principle of forcing fluids through a small orifice, generating a high pressured stream that penetrates into the skin with high velocity. There are numerous predictive “preskin” biophysical trials and predictive models, but there are rare models of evaluation of intramuscular penetration, and dispersion characteristics in vivo. Therefore the proposed method provides valuable and reliable information, is objective, repeatable and reproducible, not expensive, and allows the comparison of in vivo efficacy of various NFID.