Survey of infectious agents involved in acute respiratory disease in finishing pigs

Outbreaks of respiratory disease constitute a major health problem in herds of finishing pigs and their aetiology often remains unclear. In this study . 16 outbreaks of respiratory disease with acute clinical signs in finishin g pigs were investigated to determine which infectious agents were involved . From each herd four diseased and two clinically healthy pigs were examine d pathologically and for the presence of viruses. bacteria and mycoplasmas. In addition, paired blood samples from 10 groupmates of the diseased pigs were tested for antibodies against commonly known causal agents of respirat ory disease. A clear diagnosis was possible in 12 of the 16 outbreaks. Seve n were due to an infection with influenza virus and five were due to an inf ection with Actinobacillus pleuropneumoniae. A combination of influenza vir us and A pleuropneumoniae may have caused one other outbreak, but no clear cause could be established for the other three outbreaks.