Survey of <i>Mycoplasma (Mesomycoplasma) ovipneumoniae, Mannheimia haemolytica</i>, and <i>Pasteurella multocida</i> in pneumonic lungs from sheep slaughtered at 3 abattoirs in New South Wales, Australia.

Respiratory disease is common in sheep worldwide. The objective of this study was to use real-time polymerase chain reaction (PCR) on bronchial swabs collected from sheep lungs with gross pathological signs of ovine respiratory complex (ORC) at abattoirs in southeastern Australia to detect 3 common bacterial ovine respiratory pathogens <i>[Mycoplasma (Mesomycoplasma) ovipneumoniae, Mannheimia haemolytica</i>, and <i>Pasteurella multocida]. Mycoplasma ovipneumoniae</i> was the most detected (35% of samples), followed by <i>M. haemolytica</i> (14.9% of samples), and <i>P. multocida</i> (8.1% of samples). The most common combination of infections was <i>M. ovipneumoniae</i> plus <i>M. haemolytica</i> (48 samples, 14.7% of positive samples), followed by <i>M. ovipneumoniae</i> plus <i>P. multocida</i> (21 samples, 6.4% of positive samples), and <i>M. haemolytica</i> plus <i>P. multocida</i> (19 samples, 5.8% of positive samples). There was a weak positive correlation between samples positive for <i>M. ovipneumoniae</i> and samples positive for <i>M. haemolytica</i> (<i>r</i> = 0.14, <i>P</i> = 0.002), a weak positive correlation between samples positive for <i>M. ovipneumoniae</i> and samples positive for <i>P. multocida</i> (<i>r</i> = 0.08, <i>P</i> = 0.002), and a weak-to-moderate positive correlation between samples positive for <i>M. haemolytica</i> and samples positive for <i>P. multocida</i> (<i>r</i> = 0.25, <i>P</i> < 0.001). Further research is needed on management options for ORC in Australian sheep farmed in extensive grazing systems.