Analysis of right ventricular areas to assess the severity of ascites syndrome in broiler chickens

Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Canada.

Ascites syndrome in broiler chickens is defined as a condition associated with pulmonary hypertension leading to right heart failure, increased central venous pressure, passive congestion of the liver, and accumulations of serous fluids in body cavities. The syndrome is currently seen in fast-growing broiler chickens associated with an increase in the weight, volume, and area of the right ventricle of the heart. The ratio of the right ventricle weight to the total heart mass has been used to assess the consequences of increased blood pressure. The right ventricle area (RVA) can be quantified using image analysis technology. Hearts were removed from 719 male broilers at slaughter (42 d). All birds were visually scored for the incidence of ascites. A score of 0 or 1 represented slight hydropericardium, slight right heart hypertrophy, and slight edema. A score of 4 was assigned to birds with marked accumulation of ascitic fluid in one or more ceolomic cavities, pronounced dilation of the right heart, and prominent liver lesions. A cross-sectional image of each heart slice (a 4-mm-thick slice of the ventricles) was digitally recorded. Using image analysis software, the RVA, left ventricular area (LVA), and total heart area (HA) were determined. Because a slice of the heart was used in image analysis, the importance of maintaining the original shape was determined. Twenty hearts in five ranges of RVA size were scanned in four different positions, which have differing heart slice orientations and differing RVA shapes, for a comparison of positioning technique (placement) relating to the RVA. The shape of the heart slice for image analysis was observed not to be critical for the small RVA. For heart slices with large RVA values, it was found to be critical to analyze the heart slice in a standardized placement.