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 ≥TUS_1cm = 5.2 mmol/L 25%-75% interquartile range [IQR] 4.5-6.1, <TUS_1cm = 5.9 mmol/L IQR 5.5-6.6; ≥TUS_3cm = 5.1 mmol/L IQR 4.4-6.2, <TUS_3cm = 5.8 mmol/L IQR 5.3-6.4). Paraoxonase-1 was significantly lower (P < .001) in TUS-affected calves (≥TUS_1cm = 64.1 U/mL IQR 40.8-78, <TUS_1cm = 77.3 U/mL IQR 61.9-96.5; ≥TUS_3cm = 59.2 U/mL IQR 37.7-72.4, <TUS_3cm = 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.

Keywords: blood gas analysis; calves; clinical signs; respiratory disease; thoracic ultrasonography.