Actinobacillus pleuropneumoniae causing porcine pleuropneumoniae is responsible for lowered productivity and reduction of performance indicators such as daily weight gain and increase of losses in the swine industry worldwide. To control the disease, vaccination is used to reduce clinical signs and production losses. A randomized, blinded field trail was conducted to compare two licensed A. pleuropneumoniae vaccines in 600 finishing pigs in terms of lung lesions, mortality, medication, weight gain and safety, in a farm in northeast Germany. After weaning, pigs were allocated randomly in two groups resulting in group sizes of 300 individuals. Nursery pigs were vaccinated at the age of 7 to 10 weeks either with a A. pleuropneumoniae bacterin, containing ApxI-III toxoids (group 1), or with a subunit purified A. pleuropneumoniae toxoid vaccine (group 2). Blinded lung lesion scoring at slaughter following the Ceva Lung Program methodology revealed a significantly lower proportion of lungs affected with pleurisy in group 1 compared to group 2. Weighing of the animals did not show a significant difference (p = 0.092); however, at the end of finishing animals of group 1 showed a 1.59 kg higher weight (100.40 ± 10.15 kg) compared to animals in group 2 (98.81 kg ± 11.56 kg). Mortality and antimicrobial medication were significantly lower in group 1 compared to group 2 (13 losses and 17 antimicrobial medications in group 2, 4 losses and 1 antimicrobial medications in group 1). Injection site and systemic adverse reactions were recorded on both days of vaccination and did not differ significantly between the groups (p > 0.05). In this study, the efficacy of vaccination with a commercially available A. pleuropneumoniae bacterin containing ApxI-III toxoids was superior to that of a commercially available A. pleuropneumoniae subunit toxoid vaccine in preventing pulmonary lesions associated with A. pleuropneumoniae infection.Grzegorz Woźniakowski