A case report of a complete situs inversus in a Wistar rat

Background: Complete situs inversus is a rare situation when all the organs of the living organism are present but they are on the opposite side. Discovering situs inversus in animals is very difficult because there is no external sign of the abnormal anatomical situation in most cases. Most animal data are published by veterinary doctors, who discover it during an examination, but the occurrence and publication of these data are very rare. Materials and methods: While a male Wistar rat was being used for educational purposes the teacher accidentally discovered that the internal organs were in an unusual anatomical location. First laparotomy, then thoracotomy was performed for confirming the assumption that this was a case of a complete situs inversus. Results and Discussion: During the examination, the following occurrences were ooserved: The spleen was situated on the right side. The pars oesophageal of the stomach, which is identified by its white colour, was positioned on the right, and the pylorus was located in the median line. The stomach was located on the right side. The lobes of the liver were positioned in a way that seemed to be the mirror image of the situs solitus situation. Its biggest lobe could be seen on the right side, and the bigger right medial lobe was on the left side. The left kidney and its blood vessels together with the ureter were in cranial position. Dextrocardia was obse'ved in the thorax. The direction of the heart apex was reversed compared to the normal position, in which case the heart is located on the left side and the apex is directed to the left side, and the arcus aortae reached the heart from the right. The oesophagus was located on the right side of the trachea. Moreover, it became apparent that the right lung had only one lobe while the left lung had 4 lobes as a reflection of a normal situation. At the end of the dissection process, it was concluded that a complete situs inversus was discovered in this laboratory rat. The animal was asymptomatic. There were no visible signs that it had abnormal organ location.