Preliminary evidence that hydrostatic edema may contribute to the formation of diffuse alveolar damage in a Holstein calf model [version 1; peer review: 2 approved]

• Published in: F1000 research Vol. 7; p. 374
• Main Authors: Neary, Joseph M, Church, Dee
• Format: Journal Article
• Language: English
• Published: England Faculty of 1000 Ltd 2018; F1000 Research Limited; F1000 Research Ltd
• Subjects: Adrenergic beta-Agonists - pharmacology; Alveoli; Animals; Arterial Pressure - drug effects; Blood pressure; Body mass; Bovidae; Cattle; Disease; Disease Models, Animal; Drug dosages; Echocardiography; Edema; Heart; Heart failure; Histology; Hydrostatic Pressure; Hypertension, Pulmonary - chemically induced; Hypertension, Pulmonary - complications; Hypertension, Pulmonary - veterinary; Hypertrophy; Isoproterenol - administration & dosage; Lungs; Male; Mitral valve; Permeability; Pneumonia; Pulmonary Alveoli - pathology; Pulmonary Edema - etiology; Pulmonary Edema - pathology; Septum; Velocity; Ventricle; Ventricular Dysfunction, Left - complications; Ventricular Dysfunction, Left - veterinary; West Texas; United States > US; acute respiratory distress syndrome; congestive heart failure; pneumonia; left ventricle; hypertension
• ISSN: 2046-1402; 2046-1402
• DOI: 10.12688/f1000research.14153.1

Background: Two notable findings of clinically healthy feedlot cattle suggest they may have pulmonary hydrostatic edema during the finishing phase of production: increased pulmonary arterial wedge pressures and pulmonary venous hypertrophy. The goal of this study was to determine if increased pulmonary arterial wedge pressure (PAWP) in a Holstein calf could lead to diffuse alveolar damage consistent with the early, exudative phase of acute interstitial pneumonia of feedlot cattle.
Methods: Six male Holstein dairy calves were given daily subcutaneous injections of the nonspecific ß-adrenergic agonist isoprenaline (10 mg/kg/d), to induce left ventricular diastolic dysfunction, or sterile water for 14 days. On Day 14, pulmonary arterial pressures and wedge pressures were measured, echocardiography performed, and the ratio of mitral valve flow velocity (E) to septal lengthening velocity (e') calculated. Calves were euthanized on Day 15 and lung lesions semi-quantitatively scored.
Results: Mean PAWP was 12 ± 1 mm Hg in calves that received isoprenaline and 7 ± 1 mm Hg in controls (
P = 0.01). Calves that received isoprenaline tended to have greater relative wall thickness than control calves (
P = 0.15) and greater E/e' ratios (
P = 0.16), suggestive of concentric hypertrophy and diastolic dysfunction, respectively. Calves that received isoprenaline also tended to have a left ventricle and interventricular septum that was 29 ± 10 g heavier than control calves (
P = 0.10) when controlling for body mass. Hyaline membranes, the hallmark feature of diffuse alveolar damage, were evident in lung sections from all calves that received isoprenaline but none of the controls.
Conclusions: Consistent with prior pathological and physiological studies of feedlot cattle, this study provides preliminary evidence that cattle presenting with clinical signs and pathology consistent with early stage acute interstitial pneumonia could be attributable to hydrostatic edema associated with left ventricular failure.