Page 295 - Feline diagnostic imaging

17.3 ­neumomediastinum 299

Figure 17.8 Lateral thoracic image of a cat presented for regurgitation and weakness. A small mediastinal mass is noted just cranial
and ventral to the heart. The cervical and cranial thoracic esophagus is moderately dilated. Thymoma and myasthenia gravis was the
final diagnosis.

(b)

(a)

Figure 17.9 Lateral (a) and ventrodorsal (b) thoracic images of a cat presented for vomiting and weight loss. The sternal lymph node
is enlarged, creating a cranial and ventral mediastinal mass (arrows). This cat had a focal jejunal mass diagnosed as lymphosarcoma.

and bronchovascular sheath, into the mediastinal space tion and positive pressure ventilation (possible baro-
(Macklin effect) [18]. This can occur completely sepa- trauma and tracheal rupture), followed by trauma and
rately from lung trauma that results in a pneumothorax. tracheal foreign bodies, were described in one study as the
Pneumomediastinum secondary to necrotizing viral most common causes of pneumomediastinum [20,21].
pneumonia (feline herpesvirus‐1) was reported as a cause Less commonly, air can enter the mediastinum from
of subcutaneous emphysema and pneumomediastinum in gas accumulation in the retroperitoneal space. In some
one cat [19]. General anesthesia with endotracheal intuba- cases, the cause of pneumomediastinum is not determined