Thoracic Ultrasonography and Bronchoalveolar Lavage Fluid Analysis in Holstein Calves with Subclinical Lung Lesions

Abstract

BackgroundThoracic ultrasonography (US) and bronchoalveolar lavage fluid (BALF) analysis are antemortem methods used to identify the lung lesions associated with bovine respiratory disease (BRD). Accuracy of US and the cell distributions in BALF have not been characterized in calves with subclinical disease.ObjectivesTo evaluate the accuracy of US and BALF and describe BALF characteristics in calves with subclinical lung lesions.AnimalsTwenty‐five Holstein calves, 1–12 weeks old.MethodsIn this prospective study, calves with low respiratory scores underwent US, BALF and postmortem examination (normal US, n = 5; comet‐tails, n = 5; consolidation, n = 15). Bronchoalveolar lavage fluid was collected and analyzed for total and differential cell counts. Lung lesions were assessed by gross and histopathologic examination. Data were analyzed using nonparametric methods and relative risk analysis. The accuracy of US and BALF were estimated relative to postmortem examination.ResultsThe sensitivity and specificity of US for detecting lung lesions was 94% (95% CI, 69–100%) and 100% (95% CI, 64–100%), respectively. A cut‐point of ≥4% BALF neutrophils was associated with the highest BALF sensitivity and specificity, 81% (95% CI, 56–94%) and 75% (95% CI, 36–95%). The presence of consolidation on US increased the risk of having a BALF neutrophil proportion ≥4% (RR, 3.9; 95% CI, 1.13–13.45; P = .003).Conclusions and Clinical ImportanceUltrasonography accurately detects lung lesions in calves with subclinical disease. Clinicians should use a cut‐point of ≥4% BALF neutrophils to diagnose subclinical respiratory disease.

Validation of a clinical scoring system for bovine respiratory disease complex diagnosis in preweaned dairy calves using a Bayesian framework

“…One limitation of the present study is due to the imperfect test that was used as a proxy of BRD. Thoracic ultrasound is a fast and reliable test to detect BRD induced lung lesions (Ollivett et al, 2015). Moreover, it can be performed even by relatively novice ultrasound operator (Buczinski et al, 2013).…”

Incremental Value (Bayesian Framework) of Thoracic Ultrasonography over Thoracic Auscultation for Diagnosis of Bronchopneumonia in Preweaned Dairy Calves

“…The TUS was performed using an ultrasound unit with a 7.5 MHz, linear‐array transducer . The thoracic area scanned was slightly modified from a previous study, as it also included the right lung field cranial to the heart (1st–2nd intercostal spaces), as described . An abnormal TUS was defined by the presence of any area of consolidated lung with a depth ≥1 cm (using the 1‐cm grid of the ultrasound apparatus; Fig ) …”

Association of lung lesions measured by thoracic ultrasonography at first diagnosis of bronchopneumonia with relapse rate and growth performance in feedlot cattle

“…Thoracic ultrasonography was performed by the same experienced clinician using an Ibex Pro device (EI Medical Imaging, Loveland, Colorado) using a 6.2 MHz linear probe, maximal depth, 9 cm; total gain, 32 dB (far gain, 36 dB; near gain, 13 dB) as described previously . The thorax was neither shaved nor clipped before performing TUS, and isopropyl alcohol (70%) was used as a transducing agent, as described previously . Because a previous study indicated that lung lesions associated with negative outcomes in feedlot steers were located in the mid‐to‐ventral section of the thorax, only the mid‐to‐ventral portions of the 4th, 5th, and 6th intercostal space were examined (1st to 3rd intercostal spaces cannot be not scanned in animals of this size, particularly when they are restrained in a chute [SB, personal communication]).…”

“…Severity of lung lesions was evaluated offline as described by a clinician experienced in TUS and blinded to health and performance outcomes. Briefly, for each video, quantitative assessment of the maximal depth (in cm) and maximal area (manually counting the number of squares with consolidated lung; in cm 2 ) of lung consolidation was performed using the squared screen (1 cm 2 ) of the video recording as landmark.…”