The study investigated whether the repeat use of needles used to inject piglets with iron, influences the force required to puncture into piglet cadaver skin. Pig units (n = 31) were surveyed on needle reuse and injection practices, and these findings informed subsequent laboratory-based experiments on needle puncture force into piglet cadaver tissues. A 21 G 5/8" needle was reported as the most used needle type (67.7%), with 80.6% reporting needle reuse; 38.7% changed the needle between litters or earlier if damaged, 16.1% every three litters and 22.5% when it felt blunt or damaged, after each injection session or when changing the bottle of iron solution. There was a significant difference in puncture force between the 1st and 36th use (p < 0.05), and between the 1st and 100th use (p = 0.0015), but not between the 1st and 12th or 36th use (p > 0.999 and p = 0.8313, respectively). Scanning electron microscopy (SEM) imaging showed appreciable damage to the needle tip after 12 uses. The repeat use of needles in piglet cadavers increased the force of needle puncture compared to first-time use. When extrapolated to live animals, the use of blunt needles has the potential to cause pain and distress.
Keywords: animal welfare; needle reuse; piglet skin; puncture force; scanning electron microscopy.