Vertebral cardiac size and heart location of the Syrian hamster (Mesocricetus auratus) in radiographs and in situ gross dissections

Syrian hamsters (SHs) are a widely used translational cardiovascular research model and popular pets in which cardiac disease has been reported. However, despite their relevance, no information on vertebral heart size (VHS) and cardiac location in this species has been published. This study aimed to examine the hearts of SHs using radiographic and anatomical methods, focusing on VHS and cardiac location, along with the effects of sex, body weight, and body length. Twenty-four healthy adult Syrian hamsters were included in this study. Evaluation of the cardiac silhouette, its radiographic measurements, and cardiac topography was performed in 22 animals, while anatomical cardiac measurements were obtained from 18 suitable cadavers. The cardiac silhouette was typically located between the first intercostal space and the fourth rib, with the majority of the cardiac silhouette oriented to the left side of the median plane. Radiographic VHS values were significantly greater in females than in males A statistically significant inter-observer variation in the radiographic VHS was noted. No significant correlation was found between radiographic or anatomic VHS and body weight or body length. The mean radiographic and anatomic VHS were 8.9 and 6.69 vertebrae, respectively, with the former being significantly higher than the latter ( P ≤ 0.001), indicating that the magnification of the heart was greater than the magnification of the vertebrae. Regarding the origination and topography of the heart in SHs, the mean radiographic VHS in this study was larger than values reported for rabbits, rats, guinea pigs, agoutis, and prairie dogs, but smaller than those of chinchillas and mice. This study provides the first baseline reference values for VHS in Syrian hamsters and suggests that radiography, considering sex-related variations, is a reliable tool for cardiac size assessment. These findings provide useful data for both clinical and experimental cardiology in this species.