Relationship between thoracic auscultation and lung pathology detected by ultrasonography in sheep

The utility of routine auscultation to detect and characterise the nature of a range of superficial lung and pleural pathologies in domestic sheep was assessed using ultrasonographic examination to indicate and localise pathologies pre-mortem. Necropsy examination was then used to fully characterise the nature and extent of the lesions. Auscultation recordings were made from 10 normal sheep with no clinical evidence of respiratory disease and with absence of significant superficial lung pathology, which was confirmed initially by ultrasound examination and subsequently at necropsy examination. A further two sheep with endotoxaemia and 30 sheep with well-defined lung lesions were also examined. Increased audibility of normal lung sounds in 4/10 normal sheep was associated with tachypnoea as a consequence of handling and transport during hot weather and was also observed in the two sheep with endotoxaemia. Moderate to severe coarse crackles detected in all advanced cases of ovine pulmonary adenocarcinoma (n=16) were audible over an area larger than the lesion distribution identified during ultrasound examination, and confirmed later at necropsy. Auscultation did not detect abnormal sounds in any of the five sheep with focal pleural abscesses (up to 10 cm diameter). Unilateral pyothorax caused attenuation of sounds relative to the contra-lateral normal lung in all three sheep with this condition. Marked fibrinous pleurisy caused attenuation of sounds relative to normal areas of lung in six sheep. No sounds resembling the description of pleural frictions rubs were heard in the sheep with marked fibrinous pleurisy (n=6) or associated with focal pleural abscesses (n=5). Routine interpretation of auscultated sound did not allow the presence of superficial lung pathology or its distribution to be accurately defined in the respiratory diseases represented in this study.