Laryngeal paralysis associated with a muscle pseudotumour in a young dog

Abstract

An 18-month-old male entire Bloodhound dog was presented with a six-week history of progressive inspiratory dyspnoea, stridor, dysphonia and exercise intolerance. CT scan performed elsewhere had revealed the presence of an unencapsulated nodular mass (3x1x5 cm) dorsal to the larynx and first tracheal rings. Laryngoscopy demonstrated the presence of bilateral laryngeal paralysis and distorted laryngeal architecture suggestive of extraluminal compression. Histopathology results of incisional biopsies from the mass were suggestive of a benign non-neoplastic muscular lesion. Surgery was performed to manage laryngeal paralysis and attempt mass excision. A second histopathology examination confirmed an inflammatory and dysplastic lesion suggestive of a pseudotumour. All clinical signs resolved after surgery and at the 13 months follow-up the dog remains asymptomatic. To the authors' knowledge, this is the first report of a case of laryngeal paralysis caused by a muscle pseudotumour in a young dog.

Keywords: Dog; Laryngeal paralysis; Larynx; Muscle pseudotumour.

Fig. 1

CT scan images (from left to right: sagittal, transverse and dorsal plane): the mass-type lesion (short arrows) extends dorsally to the first tracheal rings and larynx, causing right lateral deviation of the proximal trachea and oesophagus; the deviation of the intraoesophageal tube appears evident (long arrows).

Fig. 2

Laryngoscopy image: The extraluminal mass distorts the normal laryngeal architecture causing narrowing of the glottis lumen (arrows) and bilateral laryngeal paralysis.

Fig. 3

Histology image: Portion of skeletal muscle with markedly distorted architecture and mild inflammatory changes. Myofibers show severe variations in size, shape and staining affinity. Disarray of orientation is evident, with fibres in transverse, longitudinal and oblique section. Degeneration, regenerative changes and fibrosis are also evident (H&E stain, 10X).