Fast lung ultrasonography (FLUS) as a rapid diagnostic method for bovine respiratory disease

Clinical scores and lung auscultation are commonly used for the diagnosis of bovine respiratory disease (BRD) in field conditions, despite low sensibility and specificity (Calf Respiratory Scoring Chart - CRSC: sensibility (Se) 55%, specificity (Sp) 58%, thoracic auscultation: Se 3-17%) [1]. Thoracic ultrasonography (TUS), on the other hand, represents the "gold standard" for the evaluation of lung damages (Se 79.4%, Sp 93.9%) [2]. However, TUS is often demanding, especially for untrained veterinarians and it is not suitable to investigate a large number of animals. The aim of this study is to evaluate the accuracy of a fast lung ultrasonography (FLUS) for the diagnosis of BRD, compared to TUS. One hundred Holstein Friesian calves, aged between 1 to 6 months, belonging to different dairy herds with different BRD prevalence, were enrolled. All calves were examined by a single operator using CRSC [3], thoracic auscultation and complete TUS [2]. Between lung lobes those are more frequently affected by BRD, for fast lung ultrasonography we scanned only those are easier to detect: the caudal aspect of cranial lobe of the left lung (IV and V left intercostal spaces), the caudal aspect of cranial lobe of the right lung (IV right intercostal space) and the middle lobe of the right lung (V right intercostal space). Both TUS and FLUS were scored using the ultrasonography scoring system proposed by Ollivett and Buczinski [2] and animals were considered affect by BRD if the score was ≥ 2. Sensibility (Se), specificity (Sp), positive predicting value (PPV), negative predicting value (NPV), accuracy (Acc) and Coehn’ Kappa concordance test (K) of FLUS were calculated using TUS as a gold standard. A total of 55 out of 100 calves had a TUS score ≥ 2 and therefore were considered affected by BRD. FLUS presented a Se = 84.62%, Sp = 100%, PPV 100%, NPV =77,78% Acc 90% and K = 0.577 (P value < 0,001). Our results suggest that FLUS is a practical and speedy method that can provide a good representation of pulmonary lesions and can be easily performed by a single operator. FLUS can be considered an additional tool to reach an early and accurate diagnosis, especially during xamination of a herd. Furthermore, FLUS can be used to apply a selective therapeutic protocol with reduction of unnecessary antibiotic treatments.