Situs inversus in a dog

ABSTRACT

Background: Situs inversus (SI) is a rare congenital malformation characterized by the transposition of the viscera (thoracic and/or abdominal) to the opposite side of its normal topography, as a mirror image. In situs inversus totalis (SIT), all organs are inverted, in addition to the cardiac apex being directed to the right side of the body (dextrocardia). It may not present any clinical signs, and hence, it may be an accidental finding. Because of the rare occurrence of SIT, no epidemiological studies have been conducted in dogs. In 50% of the cases, it may be associated with primary ciliary dyskinesia (PCD), which causes respiratory clinical signs. SIT can be diagnosed using routine examinations such as ultrasonography, radiography, tomography, and echocardiography. The objective of this paper was to describe the radiographic and echocardiographic findings in a dog with SIT.Case A 4-month-old Yorkshire Terrier bitch was admitted to the veterinary clinic, with a clinical complaint of cough. A physical examination showed that the dog’s general conditions were good; it had normal appetite and the mucous membranes had a normal color. Radiographic examination revealed changes in the topographic anatomy of the organs. The cardiac silhouette was inverted, adopting a “D” form; this suggested that the left-side chambers were positioned on the right side, and the right-side chambers were located in the left topographic region. The aortic arch was visible on the right side of the thorax. A diffuse non-structured pulmonary interstitial pattern was observed on latero-lateral projections, which could be associated with an inflammatory process. The fundic region of the stomach, spleen, and thymus were visible on the right side. The liver was on the left side of the patient’s abdomen. The stomach contained a foreign body of radiopaque nature that was considered a radiographic finding.[...]