Pleuritis in slaughter pigs: Relations between lung lesions and bacteriology in 10 herds with high pleuritis

Pleuritis in slaughter pigs has increased in recent years in the Netherlands. The aim of the present study was to determine what respiratory pathogens were involved in pleuritis. In total, lungs of 968 slaughter pigs from 10 herds with high prevalence of pleuritis were morphologically examined for size, location, and type of lesions. Moreover, histology and bacteriology were performed. Examination of gross lung lesions showed 45% pleuritis, 14% pleuropneumonia and 38% catarrhal pneumonia. Peribronchiolar cuffing was found in 61 of 142 samples. Actinobacillus pleuropneumoniae was cultured from 22 lung samples from four herds. Pasteurella multocida was cultured from 55 lung samples in eight herds. No specific pattern with respect to the causal pathogens was found. In conclusion, no single infectious cause of pleuritis was found. A variety of infectious agents combined with environmental factors should be considered as a cause of pleuriti

Pleuritis in slaughter pigs: Relations between lung lesions and bacteriology in 10 herds with high pleuritis

Pleuritis in slaughter pigs has increased in recent years in the Netherlands. The aim of the present study was to determine what respiratory pathogens were involved in pleuritis. In total, lungs of 968 slaughter pigs from 10 herds with high prevalence of pleuritis were morphologically examined for size, location, and type of lesions. Moreover, histology and bacteriology were performed. Examination of gross lung lesions showed 45% pleuritis, 14% pleuropneumonia and 38% catarrhal pneumonia. Peribronchiolar cuffing was found in 61 of 142 samples. Actinobacillus pleuropneumoniae was cultured from 22 lung samples from four herds. Pasteurella multocida was cultured from 55 lung samples in eight herds. No specific pattern with respect to the causal pathogens was found. In conclusion, no single infectious cause of pleuritis was found. A variety of infectious agents combined with environmental factors should be considered as a cause of pleuriti

Efficacy of a subunit vaccine against <i>Actinobacillus pleuropneumoniae</i> in an endemically infected swine herd

Objective: To evaluate lung lesions at slaughter after three-dose vaccination with a subunit Actinobacillus pleuropneumoniae vaccine containing ApxI, ApxII, ApxIII, and an outer membrane protein. Materials and methods: A total of 430 newborn piglets in a herd endemically infected with A pleuropneumoniae were assigned to control and treatment groups by block randomization at litter level. Pigs vaccinated at 6, 10, and 14 weeks of age and unvaccinated controls were housed in three rooms containing 12 pens each, with treated and control groups mixed in pens. Individual pig data included average daily gain (ADG), number of antimicrobial treatments, and clinical disease. Sera of vaccinated (n = 5) and control pigs (n = 6) collected at 6, 10, 14, 18, and 23 weeks of age were tested for A pleuropneumoniae antibodies using the complement fixation test and ELISAs for Apx toxins and outer membrane protein. At slaughter, lungs were examined for gross and microscopic lesions and cultured for A pleuropneumoniae. Differences in ADG and occurrence of A pleuropneumoniae-related lesions were compared between treatment groups using multilevel mixed models with room and pen as random effects. Results: Actinobacillus pleuropneumoniae-related lesions and ADG did not differ between control and treatment groups. Maternal immunity against A pleuropneumoniae was detected until 10 weeks of age. Moderate vaccine titres were observed after the third vaccination. Implications: Maternal antibody may interfere with the response to subunit A pleuropneumoniae vaccines. Postponing vaccination until 10 to 14 weeks of age might be advisable in herds with high maternal immunity

Efficacy of a subunit vaccine against <i>Actinobacillus pleuropneumoniae</i> in an endemically infected swine herd

Objective: To evaluate lung lesions at slaughter after three-dose vaccination with a subunit Actinobacillus pleuropneumoniae vaccine containing ApxI, ApxII, ApxIII, and an outer membrane protein. Materials and methods: A total of 430 newborn piglets in a herd endemically infected with A pleuropneumoniae were assigned to control and treatment groups by block randomization at litter level. Pigs vaccinated at 6, 10, and 14 weeks of age and unvaccinated controls were housed in three rooms containing 12 pens each, with treated and control groups mixed in pens. Individual pig data included average daily gain (ADG), number of antimicrobial treatments, and clinical disease. Sera of vaccinated (n = 5) and control pigs (n = 6) collected at 6, 10, 14, 18, and 23 weeks of age were tested for A pleuropneumoniae antibodies using the complement fixation test and ELISAs for Apx toxins and outer membrane protein. At slaughter, lungs were examined for gross and microscopic lesions and cultured for A pleuropneumoniae. Differences in ADG and occurrence of A pleuropneumoniae-related lesions were compared between treatment groups using multilevel mixed models with room and pen as random effects. Results: Actinobacillus pleuropneumoniae-related lesions and ADG did not differ between control and treatment groups. Maternal immunity against A pleuropneumoniae was detected until 10 weeks of age. Moderate vaccine titres were observed after the third vaccination. Implications: Maternal antibody may interfere with the response to subunit A pleuropneumoniae vaccines. Postponing vaccination until 10 to 14 weeks of age might be advisable in herds with high maternal immunity