Evidence of cor pulmonale and liver disease in association with pneumonia in feedlot and dairy cattle at an altitude of 975 m

• Published in: Journal of animal science Vol. 94; p. 83
• Main Authors: Gulick, A K, Neary, J M
• Format: Journal Article
• Language: English
• Published: Champaign Oxford University Press 01.10.2016
• Subjects: Altitude; Bovidae; Cardiac output; Cardiac ventricles; Cattle; Congestion; Dairy cattle; Death; Distension; Enlargement; Epidemiology; Fatalities; Feedlots; Feeds; Health risks; Heart; Heart diseases; Histology; Hyperplasia; Hypertrophy; Lesions; Liver; Liver diseases; Lung diseases; Mortality; Myocardium; Organs; Oxygen requirement; Pneumonia; Reduction; Respiratory diseases; Risk factors; Ventricle
• ISSN: 0021-8812; 1525-3163
• DOI: 10.2527/jam2016-0171

The objective of this observational study was to determine if cor pulmonale is evident in cattle at the moderate altitude of 975 m. Cor pulmonale is defined as right ventricular enlargement and dysfunction due to diseases affecting the lung or pulmonary vasculature. Right ventricular dysfunction can manifest as congestive hepatopathy. A convenience sample of necropsies were performed on one feedlot (n = 16) and one dairy (n = 4) between May 16 and September 4, 2015. A case history was obtained, gross lesions were recorded, and the cardiac ventricles weighed to determine the ratio of right ventricular free wall to total ventricular myocardium (RV:T). Sections of the right diaphragmatic, middle, and cranial lung lobes and liver were collected for histology. Vascular and hepatic lesions were scored semiquantitatively. Of the 16 feedlot cattle necropsied, 2 died from cor pulmonale secondary to bronchointerstitial pneumonia, 8 died from pneumonia, and 6 died from miscellaneous causes. Dairy cattle died from interstitial pneumonia (n = 3) and miscellaneous causes (n = 1). The RV:T ratio varied according to cause of death (P < 0.001): 0.37 ± 0.02 in cattle that died of cor pulmonale, 0.28 ± 0.01 in cattle that died of pneumonia, and 0.25 ± 0.01 in cattle that died of miscellaneous diseases. All cattle showed histological evidence of pulmonary vascular remodeling regardless of the cause of death or degree of right ventricular hypertrophy. The predominant vascular lesions included pulmonary arterial adventitial hyperplasia and pulmonary venous distension. Anatomic reduction of the pulmonary vascular bed was evident in cattle with pneumonia. Liver disease, consisting of sinusoidal dilation, lipidosis, and necrosis, was most severe in cattle that died of cor pulmonale and pneumonia. These findings indicate that cor pulmonale may be more problematic in cattle at modest elevation than is currently appreciated and confirm our previous epidemiological findings that respiratory disease is a risk factor for cor pulmonale in cattle. Venous congestion secondary to cor pulmonale may have contributed to the development of liver disease in cattle with pneumonia. Systemic consequences of right heart failure result from a reduction in cardiac output and venous congestion; consequently, organs with high oxygen requirements, such as the liver, are most at risk of cellular dysfunction and death. Moreover, because respiratory disease is a risk factor for cor pulmonale and the clinical signs overlap, the true incidence of cor pulmonale may be greater than current estimates suggest.