A New Canine Laryngeal Entity: Bilateral Movable Inflammatory Masses with Excellent Surgical Outcomes

Clinical characteristics and histopathologic features of movable inflammatory laryngeal masses in five dogs

Aki Fujiwara-Igarashi; Sho Goto; Yuta Nakazawa; Takafumi Ohshima; Haruyoshi Tetsu; Kenichi Inaba; Yukino Machida; Masaki Michishita

Background

Inflammatory laryngeal masses in dogs are rarely reported, and available information regarding their clinical presentation, pathology, and outcomes is limited. While inflammatory laryngeal disease is more commonly described in cats, canine cases are uncommon and often documented only as isolated reports. The authors aimed to characterise the clinical features, diagnostic imaging findings, histopathological characteristics, and outcomes of dogs with a previously unreported presentation: bilateral, movable inflammatory laryngeal masses originating from the laryngeal ventricles.

Methods

Medical records from two veterinary referral centres (2021–2023) were retrospectively reviewed. Five dogs diagnosed with inflammatory laryngeal masses were included. Clinical signs, laboratory findings, radiography, fluoroscopy, echolaryngography, and endoscopic examinations were assessed. All dogs underwent laryngoscopic surgical excision of the masses. Histopathological examination of excised tissue was performed, and follow-up data were collected to assess clinical outcome and recurrence.

Results

The median age of affected dogs was 11 years, with Yorkshire Terriers overrepresented. Clinical signs were mild and intermittent, most commonly stridor, followed by dysphonia and snoring. Imaging demonstrated soft tissue masses within the laryngeal lumen that were movable and displaced cranially during expiration. Endoscopy revealed bilateral, pedunculated masses originating from the laryngeal ventricles in all dogs. Histopathology consistently demonstrated chronic laryngitis characterised by lymphoplasmacytic infiltration, fibrosis, edema, and lymphangiectasia, with occasional neutrophilic inflammation. Surgical excision resulted in rapid resolution of clinical signs, and no recurrence was observed during a median follow-up period of 13 months.

Limitations

The study was limited by its small sample size and retrospective design. Postoperative laryngoscopic evaluation was not performed, meaning subclinical recurrence could not be fully excluded. Additional diagnostic investigations, such as immunohistochemistry or molecular testing, were not undertaken, preventing complete exclusion of underlying lymphoproliferative disease.

Conclusions

This case series describes a novel presentation of bilateral, movable inflammatory laryngeal masses in dogs, likely representing chronically inflamed and everted laryngeal saccules. These lesions were associated with mild clinical signs and a favourable prognosis following surgical excision. The findings support the use of fluoroscopy and echolaryngography as minimally invasive diagnostic tools and suggest that surgical management alone may be sufficient for long-term resolution.

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