History
A 4-month-old sexually intact male Pug was evaluated because of a protrusion over the caudal aspect of the sternum. On physical examination, the dog did not have any signs of pain and was bright, alert, and responsive. On palpation of the rib cage, there was an external protrusion of the sternum palpated at the level of the xiphoid. The lung sounds were clear on thoracic auscultation, and the patient was eupneic. The heart rate and rhythm were normal, and no murmurs were ausculted. Radiographs of the thorax were obtained (Figure 1).
Right lateral (A) and ventrodorsal (B) radiographic views of the thorax of a 4-month-old sexually intact male Pug evaluated because of a protrusion over the caudal aspect of the sternum of 2 months' duration.
Citation: Journal of the American Veterinary Medical Association 238, 5; 10.2460/javma.238.5.565
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Radiographic Findings and Interpretation
On the lateral view, the sternum has 7 rather than 8 sternebrae and moderate ventral deviation of the sternum at the level of the xiphoid is evident. On the ventrodorsal view, the cranial mediastinum appears wide with concave margins; this finding is considered to be typical for Pugs. The apex of the heart extends caudal to the last sternal segment on the lateral view. There is a ventral protrusion of the skin and subcutaneous tissues along the caudal edge of the ventral thoracic region in the area of the caudal edge of the last sternal segment (Figure 2). These findings are consistent with pectus carinatum.
Same radiographic images as in Figure 1. On the lateral view (A), notice that the sternum has 7 rather than 8 sternebrae with moderate ventral deviation of the sternum at the level of the xiphoid. The apex of the heart extends caudal to the last sternal segment (small arrows). There is a ventral protrusion of the skin and subcutaneous tissues along the caudal edge of the ventral thoracic region in the area of the caudal edge of the last sternal segment (large arrows). On the ventrodorsal view (B), the cranial mediastinum appears wide with concave margins (arrows); this radiographic finding is considered to be typical for Pugs.
Citation: Journal of the American Veterinary Medical Association 238, 5; 10.2460/javma.238.5.565
Comments
Physical examination and radiographic findings in the dog of this report revealed a deformity of the caudal portion of the sternum, including absence of a sternal segment. A diagnosis of pectus carinatum is easily made on the basis of findings on thoracic radiographs. In the dog of this report, thoracic radiographs were evaluated further for any concurrent abnormalities (eg, cardiac abnormalities or signs of pneumonia), and none were noted. Some humans with pectus carinatum may develop a rigid chest wall, in which the chest diameter is almost fixed in full inspiration. In these patients, respiratory efforts are less efficient, and as a consequence, lung compliance can potentially be decreased.1 In dogs and cats with pectus carinatum, the condition may be associated with congenital cardiac disease as well.2 No cardiac abnormalities were observed in our patient. Pectus carinatum is defined as a protrusion abnormality of the sternum, characterized by an idiopathic overgrowth of the costal cartilages.1 In the dog of this report, no further diagnostic or therapeutic procedures were performed because of the lack of clinical signs attributable to the deformity. The owner was instructed to observe the dog for clinical signs of disease including respiratory distress, collapse, or exercise intolerance. If any of these signs developed, further diagnostic tests, including electrocardiography, echocardiography, and blood gas analysis, could be performed. For some owners, the major concern is cosmetic. However, 4 months after initial evaluation of this dog, the owner reported that the dog's sternal area appeared physically normal.
Radiographs of the thorax provide information about any possible associated intrathoracic disease, severity of the lung compression, and mediastinal displacement. Thoracic radiography may also reveal the degree of cranial displacement of the sternum, particularly in relation to the vertebral column. However, it does not provide any information about the appearance of the affected ribs because the cartilaginous part is the involved part and is not visible on radiographic images. In addition, thoracic radiography allows for assessment of the vertebral column and possible associated scoliosis, a common finding in many patients with pectus carinatum. Computed tomography can provide helpful information related to the commonly seen asymmetry of the thorax in patients with pectus carinatum.
- 1.↑
Kravarusic D, Dicken BJ, Dewar R, et al. The Calgary protocol for bracing of pectus carinatum. J Pediatr Surg 2006; 41:923–926.
- 2.↑
Suter PF. Pectus carinatum. In: Suter PF, Lord PF, eds. Thoracic radiography: a text atlas of thoracic diseases of the dog and cat. Wettswil, Switzerland: Suter, 1984;162–163.