Pectus Excavatum is a congenital developmental deformity of the anterior chest wall, characterized by the dorsal deviation of the caudal sternum and associated costal cartilages or a ventral to dorsal narrowing of the entire thorax in which several ribs and the sternum grow abnormally. It has been reported in dogs, kittens, lambs and calves. Burmese kittens and Brachycephalic dogs are more predisposed. Common clinical signs include increased inspiratory effort, inspiratory stridor, moist rales, dyspnea and exercise intolerance. Cardiac murmurs associated with concurrent cardiac defects or compression of the heart and kinking of the great vessels are common. Increased pressure in utero, rickets and increased traction on the sternum due to abnormalities of the diaphragm have been postulated as specific mechanisms. Pectus Excavatum is initially suspected from visual examination of the anterior chest. The radiographic confirmation of Pectus Excavatum is based on the thoracic shape and radiographic changes. Cardiac malposition is usually seen, with the heart shifted to the left of midline and sometimes cranially. More objective parameters have also been suggested including the Fronto-sagittal index (FSI) and vertebral index. More recently the “Haller index” has been used based on CT scan measurements. An index over 3.25 is often defined as severe. Patients with mild disease (flat chest) may become normal without surgical intervention. However, animals with moderate or severe disease need surgical intervention. Severity of this condition is repaired in animal by surgical removal of the affected portion of the sternum and replacement with a graft and also by using a cast with sutures around the sternum.