Welfare Benefits of Intradermal Vaccination of Piglets

Abstract

Vaccination is reported as a stressful and painful event for animals. This study investigated whether needle-free intradermal vaccination improves the welfare of weaned pigs through the reduction of stress and pain biomarkers and improvement of behavioural parameters compared to traditional intramuscular injection with a needle. A total of 339 weaned piglets were allocated to 3 treatment groups: Intradermal Application of Liquids (IDAL) pigs, vaccinated against Porcine Circovirus type 2 (PCV2) by means of intradermal vaccination using a needle-free device Porcilis® PCV ID; Intramuscular (IM) pigs vaccinated against PCV2 with Porcilis® PCV intramuscularly with a needle; CONTROL pigs were managed identically but did not receive any vaccine injection. At the time of the injection, the reaction of IDAL piglets was similar to control piglets, whereas a greater percentage of piglets vaccinated intramuscularly displayed high-pitch vocalizations (7% CONTROL, 7% IDAL, 32% IM) and retreat attempts (3% CONTROL, 7% IDAL, 39% IM). The day after vaccination, IDAL piglets did not differ from the control piglets for any of the behavioural variables studied through scan samplings. IM piglets showed a lower frequency of social negative interactions (p = 0.001) and rope manipulation (p = 0.04) compared to the CONTROL group. Resting postures did not differ between treatments. At 28 h post-vaccination, IDAL piglets presented lower blood C-reactive protein levels (CONTROL = 20 μg/mL; IDAL = 39 μg/mL; IM = 83 μg/mL, p < 0.0001) and blood Haptoglobin (CONTROL = 1.8 mg/mL; IDAL = 1.9 mg/mL vs. IM = 3.1 mg/mL, p < 0.0001) compared to IM piglets. Salivary chromogranin A and alpha-amylase did not differ between treatment groups when measured 25 min post-vaccination. The method of vaccination did not affect the growth of the piglets or their rectal temperature. These results support that needle-free intradermal vaccination reduces vaccination-related pain in growing pigs.

Intramuscular vs. Intradermic Needle-Free Vaccination in Piglets: Relevance for Animal Welfare Based on an Aversion Learning Test and Vocalizations

“…This agrees with the results presented by Scollo et al ( 14 ) and Temple et al ( 13 ) with regard to differences between intradermal and intramuscular administration, although Scollo et al ( 14 ) did not use a Control group and Temple et al ( 13 ) found no differences between the control and intradermal groups. Actually, the percentage of piglets that vocalized during the vaccination was slightly lower in Temple et al ( 13 ), 7, 7, and 32% for the Control, intradermal, and intramuscular groups, respectively, as compared to Scollo et al ( 14 ), who reported 45 and 75% for intradermal and intramuscular administrations, respectively, and to the present study, with 12, 52, and 88% for the Control, Hipradermic, and IM treatments, respectively. However, a reason for this difference could be that Temple et al ( 13 ) considered just high-pitched vocalizations assessed by direct observation, and not recorded.…”

“…For instance, a papule in the Hipradermic and a blood spot in the intramuscular groups were seen up to 10 min after vaccination, but the presence of crusts and redness areas achieved a maximum in both treatments just at the end of the assessment of activity budgets the day of vaccination (8 h after vaccination) and were maintained in similar values the day after (30 and 58% of crust in Hipradermic and IM treatments, respectively, and 33–24% and 25–21% of redness areas the day of the vaccination–day after the vaccination in the Hipradermic and IM treatments, respectively). These results disagreed with those obtained by Temple et al ( 13 ), where the piglets vaccinated intramuscularly did not show any visible reaction, but in accordance with these authors, the piglets from the present study did not present any abscess-like reaction 21 days post-vaccination.…”

“…In fact, the prevalence of this behavior was less than 0.5% of the total activity registered; therefore, probably, any conclusion on this would be too speculative. Conversely, Temple et al ( 13 ) found a decreased activity in intramuscularly injected piglets, in comparison to the intradermal group, including less exploratory and negative social behavior, whereas Göller et al ( 12 ) found a faster recovery of the sucking behavior in unweaned piglets intradermally vaccinated than when they were injected intramuscularly. Nevertheless, these studies were performed with different adjuvanted vaccines.…”

“…However, Scollo et al ( 14 ) argued that the lack of differences in plasma cortisol between these two different routes of administration of a vaccine might suggest that this parameter might not be sensitive enough to recognize stress during apparently low painful interventions. Temple et al ( 13 ) tried other indicators, such as salivary alpha-amylase (SAA) and salivary Chromogranin A (CgA), but they failed in showing differences between treatments as well. Therefore, it is possible that the animal could cope with the situation just with a behavioral response, with limited effects in a physiological response.…”

“…Previous studies in pigs compared intramuscular injection with intradermal injection in terms of behavioral and stress indicators in commercial farms. Behavioral indicators used included activity budgets of the animals after the administration of the vaccine, and presence, frequency, and intensity of vocalizations at the moment of the vaccination (12)(13)(14). However, the degree of aversion after vaccination has not been explored before.…”