Effect of the needle-free “intra dermal application of liquids” vaccination on the welfare of pregnant sows

BACKGROUND: In commercial pig production, sows are often vaccinated several times per gestation period, resulting in reduced welfare. This preliminary experiment investigated whether the needle-free IDAL vaccinator improves welfare through reduction of stress markers, improvement of behavioural and health parameters compared to traditional needle-syringe method. RESULTS: Two treatments (IDAL and NEEDLE) in 6 replicate pens of gestating sows (15 sows per pen) were evaluated using Porcilis® PRRS. The frequency of sows exhibiting an acute fear (or pain) response at the time of injection was significantly lower in the IDAL sows for the four indicators studied (high pitch vocalizations, IDAL = 15.4% vs. NEEDLE = 95.6%, χ2 = 56, P < 0.0001; retreat attempts, IDAL = 2.6% vs. NEEDLE = 56.5%, χ2 = 28, P < 0.0001; turning back, IDAL = 5.1% vs. NEEDLE = 69.6%, χ2 = 36, P < 0.0001; change in behaviour, IDAL = 18% vs. NEEDLE = 95.6%, χ2 = 53, P < 0.001). Sows in the NEEDLE vaccination group had a decreased (P = 0.03) activity the day after vaccination compared to IDAL sows. No significant difference was observed for the other active behaviours and resting postures. Fearful reaction towards the assessor significantly (χ2 = 12, P = 0.001) increased in NEEDLE sows compared to IDAL sows the day after vaccination. At 48 h post-vaccination, IDAL sows tended to have lower blood C-reactive protein levels (IDAL = 21.3 μg/mL vs. NEEDLE = 35.8 μg/mL, P = 0.06) compared to NEEDLE sows. Blood Haptoglobin levels did not differ significantly between treatments 48 h post-vaccination. Chromogranin A tended to show a lower increase after the IDAL treatment, whereas salivary alpha-amylase and salivary cortisol did not differ between treatments when measured 25 min post-vaccination. CONCLUSIONS: These preliminary results support that needle-free intradermal vaccination is a promising strategy to reduce fear and pain reaction of gestating sows during vaccination.