Efficacy of Simultaneous Intradermal Vaccination of Swine against Porcine Circovirus 2, Porcine Reproductive and Respiratory Syndrome Virus, Mycoplasma hyopneumoniae and Lawsonia intracellularis

SIMPLE SUMMARY: Porcine circovirus 2, porcine reproductive and respiratory syndrome virus, Mycoplasma hyopneumoniae and Lawsonia intracellularis, are four highly prevalent, major pathogens of swine for which routine vaccination is common. This study determined whether the intradermal application of vaccines against these four pathogens at the same time and at the same anatomical site had any negative effect on vaccine efficacy. Intradermal vaccination and reduced handling moments offer a more animal-friendly method of vaccination. For all four diseases, the efficacy with the combination of vaccines was equivalent to that with the single vaccines. ABSTRACT: The combined application of vaccines in swine offers many benefits, including reduced time and labour costs, and improved animal welfare, due to fewer injections and manipulations. This study investigated if simultaneous intradermal vaccinations against porcine circovirus 2, porcine reproductive and respiratory syndrome virus, Mycoplasma hyopneumoniae, and Lawsonia intracellularis, using a specialised needle-free applicator would confer comparable protection against experimental infection compared to the single vaccines. In all cases, the administration of the vaccines together was as efficacious as the administration of the vaccines alone, significantly reducing clinical signs associated with each of the four pathogens.