INTRODUCTION The pericardium is a fibroserous membrane continued with the sterno-pericardial ligament attached to the ventral aspect of the diaphragm, anchoring the heart in the thorax. Also, the pericardium restrains the cardiac filling and protects the heart from dilatation and myocardial rupture (Sisson and Thomas, 1999). Partial pericardial defects are rare in human medicine, usually silent anomalies, left sided and congenital origin, approximated to 1/10.000 and most, incidental findings, engendering a small risk of cardiac hernia (Ilhan et al., 2012; Vesely and Julsrud, 1989; Yousefzadeh et al., 1982). Hernia of the left and right atrium, atrium and ventricle, cardiac apex, or entire heart, have been reported in humans (Sisson and Thomas, 1999) and dogs (Gaag and Luer, 1977). The right pericardial anomalies are very rare findings and few cases have been described even in human medicine (Minocha et al., 1979). Sometimes, along with hernia, a myocardial strangulation is produced, generating blood ceasing and clotting. Depending on the size and location of the hernia, other topographic or physiological changes may be found. The pericardial defect can be congenital or acquired. The factors responsible for the congenital closure defects of the pericardium are connected to the embryogenesis of the coelom (Gaag and Luer, 1977). Acquired pericardial defects are often found in adults and may result due to pericardial injuries such as trauma, pericarditis, tamponade, or disruption of the pericardium (Liedtke and DeMuth, 1973). The aim of the study is to describe an uncommon cardiac pathology in a geriatric dog represented by a pericardial tear with right auricular hernia and incarceration and to explain the pathological mechanism comparing to human medicine findings, considering the association of two uncommon pathologies. The peculiarity of this case is represented by the spectacular shape and dimensions of the right auricle herniated through the pericardial tear and the unknown etiology of the pathological findings. Pericardial Closure Defect with Right Atrial Herniation in a Dog Radu Andrei BAISAN 1* , Magdalena Cristina BARBAZAN 1 , Diego PIANTEDOSI 2 , Vasile VULPE 1 1 Department of Clinical Sciences, Faculty of Veterinary Medicine, USAMV Iasi, Romania. 2 Department of Veterinary Medicine and Animal Productions, Univestity of Naples Federico II, Italy *Corresponding author: baisan.andrei_mv@yahoo.com Bulletin UASVM Veterinary Medicine 72(2) / 2015, Print ISSN 1843-5270; Electronic ISSN 1843-5378 DOI:10.15835/buasvmcn-vm: 11400 Abstract A 16 years old German Shepherd dog was referred to the teaching hospital of Veterinary Medicine Faculty of Iasi, with cardio-respiratory symptoms. Clinical examination, electrocardiography, thoracic X-ray and echocardiography have been performed and congestive heart failure due to right cardiac dilatation was diagnosed. Due to the dog’s death, necropsy have been performed and revealed a right pericardial closure defect with the hernia and incarceration of the right atrium in the mediastinum. The aim of the study is to describe an uncommon cardiac pathology in a geriatric dog represented by a pericardial tear with the right auricular hernia and incarceration and to raise hypothesis of the pathological findings etiology. Keywords: atrial hernia, dog, heart