Association of Visual Heart Score with Gross Lung Pathology and Histology of Hepatic and Cardiopulmonary Tissues in Cattle at Harvest.

Non-infectious cardiac failure in feedyard cattle has become more frequently diagnosed. There is limited research assessing gross and histologic lesions in grossly abnormal hearts of harvested cattle. Cases were stratified by heart score (HS) using a scale of 1-5, with 1 representing a normal heart and 5 representing severely remodeled ventricles. Cattle were evaluated for gross lesions of the heart, lung, and liver. Samples collected from each animal for histology included cardiac (n = 4), pulmonary (n = 4), and hepatic (n = 1) tissues. Histologic evaluation scored cardiac and hepatic fibrosis and necrosis, embedded myocardial protozoal cysts (EMPCs) were quantified, and pulmonary lesions were categorized based on histologic patterns. Of 103 cases, 40 had normal HSs (NHSs) (1 or 2), and 63 had abnormal HSs (AHSs) (3, 4, or 5). There were 64 cases with normal lung deflation scores, and 39 cases with abnormal lung deflation scores. At least one cardiac section contained EMPCs in 67 cases. Cattle with abnormal lung deflation scores were more likely to have an AHS (0.76 ± 0.07, p ≤ 0.01) compared with cattle with normal deflation scores (0.52 ± 0.06). Cattle with EMPCs present in at least one cardiac section were more likely to also have an AHS (0.73 ± 0.05, p ≤ 0.1) compared with cattle without EMPCs (0.39 ± 0.08). No histological findings for the lungs or liver were associated with abnormal heart score; however, lung deflation and EMPCs were associated with abnormal heart score.