A castrated male domestic longhaired cat of unknown age was presented for a preanesthetic evaluation before a dental treatment.
The cat was bright, alert, and responsive. A physical examination revealed a palpable pectus excavatum and severe gingivitis
with dental tartar. The cat's temperature and heart and respiratory rates were normal. No abnormalities were identified on
thoracic auscultation. The owner had not reported that the cat was symptomatic.
A thoracic radiographic examination (Figures 1-3) done as part of the preanesthetic evaluation revealed a caudoventral deviation of the xiphoid process and productive remodeling
changes at the juncture between the seventh and eighth sternebrae. A mild diffuse bronchointerstitial pattern was noted, which
may have resulted from a chronic respiratory disease such as feline asthma.
Figure 1. A left lateral thoracic radiograph reveals an enlarged cardiac silhouette and a linear soft tissue band (arrow)
connected to the diaphragm, caudoventral deviation of the xiphoid process, and a diffuse bronchointerstitial pattern.
The cardiac silhouette was markedly enlarged on all views, causing an elevation of the tracheal carina as seen on both lateral
views (Figures 1 & 2). The right border of the cardiac silhouette was outlined by a fat opacity (Figure 2), which was thought to be the falciform fat. The size of the pulmonary vessels was normal. On the left lateral view, a dorsal
peritoneopericardial mesothelial remnant connected the cardiac silhouette with the cranial diaphragmatic border (Figure 1).
Figure 2. A right lateral thoracic radiograph shows the cardiac silhouette outlined by a fat opacity.
On the ventrodorsal view (Figure 3), a pleural fissure line was visible between the right cranial and middle lung lobes. This fissure line could indicate previous
pleuritis. Partial atelectasis of the caudal subsegment of the left cranial lung lobe was also seen, with an associated lobar
sign. A coexisting lobar infiltrate could not be ruled out. As a result of the atelectasis, a mediastinal shift to the left
was present. Radiographic attenuation of the left caudal lobar bronchus was also seen. In addition, a loss of normal diaphragmatic
contour with confluence with the cardiac silhouette was noted. Also on the ventrodorsal view, a small mineralized interstitial
nodule could be seen in the right fifth intercostal space. This nodule could represent a benign nodule such as pulmonary osteoma,
an old inflammatory lesion such as an abscess, or an early pulmonary mass.
Figure 3. A ventrodorsal thoracic radiograph reveals partial atelectasis of the caudal subsegment of the left cranial lung
lobe (arrow) and a pleural fissure line between the right cranial and middle lung lobes.
Because of the loss of clear diaphragmatic outline, the enlarged cardiac silhouette with normal-sized pulmonary vessels, and
pectus excavatum, congenital peritoneopericardial hernia was the most likely diagnosis.