Auscultation is considered the critical component of the veterinary clinical examination for the diagnosis of bovine respiratory disease but the accuracy with which adventitious sounds reflect underlying lung pathology remains largely unproven because it relies upon accurate recollection of lung sounds when lesions are revealed at necrospy. Furthermore, the extent to which lung sounds change during recovery from, or deterioration in, the clinical condition has not been studied in detail.Modern portable ultrasound machines provide the veterinary practitioner with an inexpensive, non-invasive tool with which to examine the pleural surfaces and superficial lung parenchyma. Ultrasound examination of the bovine chest need take the busy farm animal practitioner no more than five minutes. Simultaneous recording of sounds overlying normal lung and defined pathology allows critical assessment of auscultated sounds in the same animal removing confounding factors such as respiratory rate and thickness of the chest wall (body condition). Twelve cows, referred to the University of Edinburgh Veterinary School, diagnosed with chronic suppurative pneumonia were enrolled into this prospective study to record and monitor lung sounds, ultrasonographic findings, and response to a standardised antibiotic treatment regimen.Most cows (8/12) had a normal rectal temperature on presentation but all cows had received antibiotic therapy at some time in the previous two weeks and six animals were receiving antibiotic treatment upon admission. All cattle were tachypnoeic (>40 breaths per minute) with frequent and productive coughing, halitosis, and a purulent nasal discharge most noticeable when the head was lowered. Ultrasonographic examination of the chest readily identified pathological changes consistent with severe lung pathology subsequently confirmed as chronic suppurative pneumonia in four cows at necropsy; eight cows recovered well after antibiotic treatment and were discharged two to six weeks after admission. The sonographic changes comprised hypoechoic columns extending 2 to 8 cm from the visceral pleura into the lung parenchyma bordered distally by bright hyperechoic lines as the transmitted sound waves contacted either normal aerated lung or small airways. More ventrally, there was an extensive hypoechoic area extending up to 10 cm from the visceral pleura containing many hyperechoic dots measuring up to 2 to 10 mm. From its most ventral margin, this hypoechoic area extended dorsally for 20 to 40 cm. It proved difficult to differentiate increased audibility of normal lung sounds due to tachypnoea from wheezes; coarse crackles were not commonly heard. In general, sounds were reduced in volume over consolidated lung relative to normal lung tissue situated dorsally. Rumen contraction sounds were commonly transmitted over areas of lung pathology.Trueperella (formerly Arcanobacterium) pyogenes was isolated from three of four lung tissue samples taken at necrospy. Treatment with procaine penicillin for 42 consecutive days resulted in marked improvement with return to normal appetite and improvement in body condition in 8 of 12 cows (67%) where lesions did not extend more than 10--15 cm above the level of the olecranon on both sides of the chest. Four cows where lesions on both sides of the chest totalled more than 40 cm did not respond to antibiotic therapy and were euthanased for welfare reasons. The cattle included in this study were referred cases and the management and care when they were returned to the home farms was not known. Recrudescence of the chronic suppurative pneumonia was considered possible after another stressful event such as parturition and the conservative decision was taken to advise owners not to re-breed recovered cases and cull them when they had regained condition.