On presentation, the dog was alert and ambulatory but exhibited moderate inspiratory stridor. He was mildly dehydrated and thin, with a body condition score of 2/5. Results of a complete blood count, serum chemistry profile, and thyroid testing (TSH and free T4 by equilibrium dialysis) were within normal limits. Thoracic radiographs were unremarkable aside from mild degenerative joint disease of the shoulders.
Given the dog’s signalment and clinical signs, laryngeal paralysis was considered the leading differential diagnosis.
To further evaluate laryngeal function, IV propofol was administered to permit a thorough laryngeal examination. Arytenoid function appeared normal, with adequate abduction bilaterally. However, distortion of the mucosa ventral to the epiglottis was observed, along with a pedunculated bridge of mucosa connecting to a mass located to the left of the larynx and extending into the proximal esophagus.
General anesthesia was then induced and maintained with isoflurane via a cuffed endotracheal tube. The dog was positioned in sternal recumbency, and Babcock forceps were used to gently retract the mass into the pharynx. The mass was cylindrical, approximately 7 cm long and 4 cm wide (Fig. 1, 2).
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| Fig. 1: Oral mass in oral cavity (held by forceps) |
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| Fig. 2: Pedunculated portion of mass (white arrow) |
The mucosal peduncle was ligated using one circumferential and one transfixing ligature of 2-0 polydioxanone, followed by sharp excision with Metzenbaum scissors. A small residual mucosal defect ventral to the epiglottis was closed with a single simple interrupted suture. No additional abnormalities or hemorrhage were noted on repeat laryngeal examination. Fine-needle aspirates of the submandibular lymph nodes, which were normal in size, were obtained prior to recovery.
Recovery from anesthesia was uneventful.
The dog was discharged two days postoperatively, breathing comfortably and able to eat and drink without difficulty. Cytologic evaluation of the lymph nodes was unremarkable. Histopathology of the excised mass revealed a high-grade neurofibrosarcoma, with complete surgical excision.
At recheck 10 days postoperatively, the owner reported marked improvement. The dog had no difficulty breathing, swallowing, or eating, and inspiratory stridor had resolved completely. Three months after surgery, the dog continued to do well, had gained weight, and remained clinically normal. Although consultation with an oncologist was recommended, the owner declined adjunctive chemotherapy or radiation therapy.
Discussion
This case represents an unusual cause of inspiratory stridor and weight loss in an older Labrador retriever. The initial presentation was highly suggestive of laryngeal paralysis, emphasizing the importance of maintaining a broad differential diagnosis in dogs with upper airway obstruction. Sedated laryngeal examination was essential in establishing the correct diagnosis.
In addition to respiratory signs, this dog had a notable history of anorexia and weight loss. The pedunculated nature of the mass allowed it to intermittently prolapse into the proximal esophagus, likely interfering with normal swallowing despite the absence of overt dysphagia reported by the owner.
Advanced imaging of the pharyngeal and laryngeal region may have aided in identifying a mass; however, the mobility of the lesion makes detection by plain radiography unlikely unless contrast material is used. Computed tomography or ultrasonography may be useful in selected cases, and ultrasonography has been described for evaluation of laryngeal disorders in dogs [1].
Neurofibrosarcomas, also classified as peripheral nerve sheath tumors, are rare in the oral cavity or pharynx of dogs. These tumors more commonly arise from peripheral nerves, the brain, or spinal cord and are considered a subtype of soft tissue sarcoma. Reported oral tumors in dogs more frequently include melanoma, squamous cell carcinoma, and fibrosarcoma. Laryngeal tumors themselves are uncommon but encompass a wide range of histologic types [2,3].
The tumor in this case was unusual not only for its histologic classification but also for its location and pedunculated morphology, which allowed complete excision without removal of any laryngeal cartilages. In contrast, most laryngeal tumors are not amenable to complete resection without aggressive procedures such as partial or total laryngectomy.
High-grade soft tissue sarcomas carry a guarded long-term prognosis due to the risk of local recurrence and metastasis [4]. More recent studies suggest improved outcomes when surgery is combined with radiation therapy [5]. Early detection and complete surgical excision remain critical, and consultation with an oncologist should be considered when feasible.
Summary
Not all Labradors with inspiratory stridor have laryngeal paralysis. Careful diagnostic evaluation, including sedated laryngeal examination, is essential before committing to definitive airway surgery. This case highlights the value of surgical judgment, restraint, and thorough assessment in achieving an excellent outcome.
References
1. Rudorf H, Barr FJ, Lane JG. The role of ultrasound in the assessment of laryngeal paralysis in the dog. Vet Radiol Ultrasound. 2001;42(4):338–343.
2. Ruppert C, Hartmann K, Fischer A, et al. Cervical neoplasia originating from the vagus nerve in a dog. J Small Anim Pract. 2000;41(3):119–122.
3. Withrow SJ, Vail DM, Page RL. Small Animal Clinical Oncology.
4. Ciekot PA, Powers BE, Withrow SJ, Straw RC, Ogilvie GK, LaRue SM. Histologically low-grade, yet biologically high-grade, fibrosarcomas of the mandible and maxilla in dogs: 25 cases (1982-1991). J Am Vet Med Assoc. 1994 Feb 15;204(4):610
5. McKnight JA, Mauldin GN, McEntee MC, et al. Radiation treatment for incompletely resected soft-tissue sarcomas in dogs.
