Clinical findings of reduced appetite, poor production, coughing, purulent nasal discharge and tachypnoea in all cases were consistent with previous reports of chronic suppurative pneumonia [14, 15]. Pyrexia was not a feature of chronic suppurative pneumonia in this study albeit all cows had received antibiotics at some stage during the previous two weeks however these antibiotic treatments had not effected any clinical improvement. This situation differs significantly from acute respiratory disease in growing cattle where fever >39.7°C is considered the most important selection criterion for antibiotic therapy [16, 17].
In the present study it proved difficult to differentiate increased audibility of normal breath sounds from wheezes; no crackles were detected over lung pathology identified ultrasonographically. In most cases, breath sounds were markedly reduced over the lung pathology. The absence of adventitious sounds, particularly crackles, is explained by the lack of air movement caused by extensive lung consolidation in these areas which had the sonographic appearance of liver. The accuracy of the sonographic findings were confirmed in all four cases at necropsy. When wheezes were identified, they were audible over the whole lung field and not restricted to the areas of lung pathology identified during ultrasound examination.
While abnormal auscultatory findings have been described over the cranioventral lung field of cattle with chronic suppurative pneumonia no details were supplied . Progression of the disease process to the stage that severe respiratory disease exists is defined whereby expiratory sounds are as harsh as inspiratory sounds  did not identify severely affected cattle in the present study.
Written descriptions of adventitious lung sounds are inadequate. Veterinary clinicians are encouraged to decide for themselves whether auscultation is useful in reaching the specific diagnosis of chronic suppurative pneumonia by examining the sound recordings in this report from normal lung and over specific pathology determined ultrasonographically. Sound recordings over specific ovine lung pathology are available to download for comparison [1, 3].
Few crackles could be identified over lung pathology despite the presence of purulent material that could be expressed from the airways of affected lung at necropsy. No readily discernible differences in lungs sounds in sheep with ovine pulmonary adenocarcinoma could be detected during auscultation between those recordings made at the margin of the tumour mass, directly over the tumour mass and in normal lung above the dorsal margin of the lesion . Studies have highlighted the lack of correlation between lungs sounds and distribution of pathology in “wheel-barrow negative” cases of ovine pulmonary adenocarcinoma despite the OPA lesions extending to involve up to 20% of lung tissue .
Trueperella pyogenes is a common bacterial isolate from chronic suppurative pneumonia in cattle [15, 20], and sheep . Extended treatment with procaine penicillin in this study was effective where lung lesions did not extend dorsally more than 10 to 15 cm above the level on the chest wall indicated by the point of the olecranon however no long term survival data are available as culling was recommended because of the likelihood of recurrence following stress (e.g. next parturition). Many drugs are used to treat dairy cows when penicillin would have sufficed .
The good treatment response in 8 of 12 cows in the present study challenges the assertion [16, 18] that all cattle with chronic suppurative pneumonia respond poorly to treatment, suffer chronic weight loss and may die as a result of an acute exacerbation of the condition. Furthermore, whether the dosing interval suits the current management  must not be considered an important factor in antibiotic selection. However, without accurate ultrasound assessment of the lungs , a provisional diagnosis of chronic suppurative pneumonia cannot be confirmed therefore treatment efficacy cannot be reliably evaluated.
Classification of the ultrasonographic changes into fine-, medium- and coarse-grained structures based upon the echogenic pattern with <10, 10–20 and >20 hyperechogenic zones per centimeter penetration of pneumonic lung tissue [13
] was considered unnecessarily complicated and did not aid formulating the prognosis. Rather, the hypoechoic changes had a distinct columnar appearance dorsally representing the lobular distribution of superficial lung pathology extending to a large hypoechoic area with the sonographic appearance of liver most graphically illustrated when both pneumonic right ventral lung, diaphragm then liver were included in the same field Additional files 3
With some experience, ultrasound examination of both sides of the chest takes only five minutes and as such would not add significant cost to the veterinary examination in general practice. Moreover, establishing the correct diagnosis  and antibiotic therapy  may prove crucial to the likely recovery of the animal; six cattle in this study receiving treatment on referral improved after the antibiotic was changed to penicillin. Responsible antibiotic use by veterinarians necessitates an accurate diagnosis and ultrasound examination provides busy farm animal practitioners with a cost-effective ancillary test for chronic respiratory disease in adult cattle.