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Trachea
Martha M. Larson

Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA

16.1 Trauma noted, but appears to be secondary to upper airway obstruc-
tion (Figure 16.3) [8–10]. Focal dynamic narrowing of the
Tracheal rupture can occur secondary to overinflation of trachea, identified primarily on inspiration, was noted in
the endotracheal tube cuff, blunt trauma, or penetrating cats caudal to a more cranially located airway obstruction,
foreign bodies [1–4]. A pneumomediastinum typically including nasal neoplasia, tracheal polyp, congenital tra-
results, with large amounts of gas within the cervical soft cheal anomaly resulting in obstruction from granulation
tissues often noted (depending on location of tracheal tissue, and histiocytic sarcoma [8–10]. It is postulated that
rupture) (Figure 16.1). Tracheal rupture secondary to an upper airway obstruction could lead to increased airway
endotracheal tube overinflation tends to be longitudinal. If resistance, increased inspiratory effort, and subsequent
there is not a complete rupture, tracheal stenosis may occur decreased intratracheal pressure during inspiration and
2–3 weeks later (Figure 16.2). Increased pressure on the tracheal collapse [9]. Careful evaluation of the trachea and
tracheal mucosa from the overinflated cuff can cause nasal cavity is recommended when tracheal collapse is
ischemic damage, followed by mucosal ulceration and noted in the cat [9].
necrosis. The underlying tracheal cartilage is resorbed,
with a resultant concentric scar formation [5].
Tracheal avulsion injury can occur after blunt trauma to 16.3 Tracheal Foreign Bodies
the head and/or thorax, with overextension injury to the
neck [6, 7]. The avulsion is usually located in the cranial Tracheal foreign bodies are relatively rare in cats [11–15].
trachea, at the level of the second, third or fourth thoracic Reported foreign bodies in cats include stones, bone frag-
vertebra. A pneumomediastinum may be present when the ments, teeth, and plant material such as twigs. The most
patient is presented immediately after the traumatic event, common location is at or just cranial to the carina
but resolves within weeks. A spherical radiolucent dilation (Figures 16.4 and 16.5). Small fragments of material could
can be identified at the level of the tracheal disruption, extend into the more peripheral airways, but this appears to
which likely represents a gas‐filled pseudo‐airway. This is be less common in cats than dogs due to their much smaller
a sequela to tracheal avulsion, forming secondary to a airway diameter. Radiopaque foreign bodies, such as stones
circumferential tracheal stenosis at the rupture site. or bone fragments, are easily visualized. However, less
opaque soft tissue structures, such as plant material, might
still be visible if surrounded by air within the tracheal lumen.
16.2 Tracheal Collapse If foreign material does extend into the smaller airways,
focal pulmonary infiltrates might be visible. However, lack
Tracheobronchomalacia, the disease process resulting in of classic radiographic signs does not rule out a foreign body,
tracheal collapse in older small‐breed dogs, has not been and additional imaging, such as computed tomography or
reported in the cat. Tracheal collapse in the cat has been bronchoscopy, might be necessary for diagnosis.

Feline Diagnostic Imaging, First Edition. Edited by Merrilee Holland and Judith Hudson.
© 2020 John Wiley & Sons, Inc. Published 2020 by John Wiley & Sons, Inc.