Blood gases, acid‐base, and metabolic alterations in calves with bronchopneumonia diagnosed via clinical signs and thoracic ultrasonography: A cross‐sectional study

Abstract Background Bronchopneumonia (BP) in calves potentially causes systemic changes. Objectives To describe metabolic, arterial blood gas, and acid‐base disorders in calves with BP diagnosed by thoracic ultrasound (TUS), Wisconsin score (WISC), and combinations of WISC and TUS. Animals Two hundred thirty‐one dairy preweaned dairy calves from 13 dairy farms. Methods Cross‐sectional study. Each calf sequentially underwent arterial blood gas evaluation, WISC score, venous sampling, and TUS. Calves were grouped based on a single diagnostic method and combination of WISC and 2 TUS cutoffs (≥1 cm; ≥3 cm) as healthy, upper respiratory tract infection, subclinical BP, and clinical BP. Results Oxygenation and acid‐base variables were unaffected. Glucose concentration in TUS‐affected calves was significantly lower (P < .001) than in healthy calves (median ≥TUS1cm = 5.2 mmol/L 25%‐75% interquartile range [IQR] 4.5‐6.1, <TUS1cm = 5.9 mmol/L IQR 5.5‐6.6; ≥TUS3cm = 5.1 mmol/L IQR 4.4‐6.2, <TUS3cm = 5.8 mmol/L IQR 5.3‐6.4). Paraoxonase‐1 was significantly lower (P < .001) in TUS‐affected calves (≥TUS1cm = 64.1 U/mL IQR 40.8‐78, <TUS1cm = 77.3 U/mL IQR 61.9‐96.5; ≥TUS3cm = 59.2 U/mL IQR 37.7‐72.4, <TUS3cm = 72.9 U/mL IQR 53.4‐95.5). None of the variables highlighted clear distinctions in WISC‐detected clinical and subclinical BP calves based on the combination of WISC and TUS. Conclusions and Clinical Importance Clinical signs indicate minor systemic disorders compared to TUS. The abnormalities detected by ultrasonographic examination were moderate and did not deviate from normal reference ranges.