Outcome of laryngeal web resection with mucosal apposition for treatment of airway obstruction in dogs: 15 cases (1992--2006)

OBJECTIVE: To evaluate long-term clinical outcome in dogs with upper airway obstruction treated with laryngeal web resection and mucosal apposition. DESIGN: Retrospective case series. ANIMALS: 15 client-owned dogs with laryngeal web formation. PROCEDURES: Medical records of dogs with laryngeal webs treated with a single procedure of web resection with mucosal apposition by use of a ventral laryngotomy were reviewed. Signalment, history, clinical signs, intraoperative complications, postoperative complications, and hospitalization time were recorded. Owners were interviewed 6 months to 6 years after surgery. RESULTS: Most dogs had a history of oral ventriculocordectomy. Duration of clinical signs ranged from 3 months to 3 years. The most common clinical sign reported was exercise intolerance. Postoperative complications were observed in 4 dogs. Follow-up information was available in 10 dogs, and clinical outcome was classified as excellent in 7 and good in 3. CONCLUSIONS AND CLINICAL RELEVANCE: A single surgical procedure of web resection with mucosal apposition for the treatment of laryngeal web formation in dogs resulted in low morbidity and was associated with a good to excellent outcome.     

Evaluation of a modified castellated laryngofissure for alleviation of upper airway obstruction in dogs with laryngeal paralysis

A modified castellated laryngofissure procedure (castellated laryngofissure, vocal fold resection, and bilateral arytenoid lateralization) was performed on 12 dogs with bilateral laryngeal paralysis. Clinical signs of airway obstruction were assessed and a pulmonary function test (tidal breathing flow volume loop) was used to evaluate the severity of obstruction. The dogs were evaluated before surgery and at various periods from 4 days to 15 months after surgery. One dog died immediately after surgery and 3 dogs died due to nonrelated or unknown causes 1, 9, and 11 months after surgery. Clinical signs of upper airway obstruction disappeared or decreased in severity in the 11 dogs that recovered from surgery. Tidal breathing flow volume loop values were normal in 7 of 10 dogs evaluated within 5 to 189 days after surgery. The modified castellated laryngofissure procedure provided successful long-term relief of upper airway obstruction associated with bilateral laryngeal paralysis.     

Upper airway obstruction in canine laryngeal paralysis

The type and the severity of airway obstruction in 30 dogs with bilateral laryngeal paralysis was assessed, using tidal breathing flow-volume loop (TBFVL) analysis. The dogs had clinical evidence of mild-to-severe upper airway obstruction (ie, respiratory distress, exercise intolerance, stridor). Seventeen dogs had TBFVL consistent with a nonfixed (inspiratory) obstruction, 10 had TBFVL indicative of a fixed (inspiratory/expiratory) obstruction, and 3 had normal TBFVL. Analysis of TBFVL confirmed that dogs with laryngeal paralysis have upper airway obstruction that differs in type and severity. Use of TBFVL provided a quantitative evaluation of airway obstruction and demonstrated the effects of bilateral laryngeal paralysis on the breathing patterns of dogs.     

Comparison of unilateral arytenoid lateralization and ventral ventriculocordectomy for the treatment of experimentally induced laryngeal paralysis in dogs.

This study evaluated changes in respiratory function in dogs with experimentally induced laryngeal paralysis treated with either unilateral arytenoid lateralization or ventral ventriculocordectomy, and compared the effectiveness of these procedures. Evaluation consisted of clinical assessment and tidal breathing flow volume loop and upper airway resistance measurements. Carbon dioxide and doxapram hydrochloride were used as respiratory stimulants. Initially, all dogs improved clinically after corrective surgery. However, by the end of the study, laryngeal collapse had developed in 2 of 5 dogs corrected by ventral ventriculocordectomy. No statistical differences in upper airway mechanics testing were seen between the surgical procedures. With both groups combined, many measurements of upper airway obstruction improved after surgical correction. Based on this study, these surgical procedures yield comparable results, although additional studies are needed to evaluate both the cause of laryngeal collapse and the role of upper airway mechanics testing in the evaluation of canine laryngeal paralysis.     

COMPUTED TOMOGRAPHIC IMAGING OF DOGS WITH PRIMARY LARYNGEAL OR TRACHEAL AIRWAY OBSTRUCTION

Seventeen dogs with clinical signs attributable to nonneoplastic obstruction of the larynx, trachea, or large bronchi underwent computed tomography (CT) imaging. In 16 of the 17 dogs, CT was performed without general anesthesia using a positioning device. Fifteen of these 16 dogs were imaged without sedation or general anesthesia. Three‐dimensional (3D) internal rendering was performed on each image set based on lesion localization determined by routine image planes. Visual laryngeal examination, endoscopy, video fluoroscopy, and necropsy were used for achieving the cause of the upper airway obstruction. The CT and 3D internal rendering accurately indicated the presence and cause of upper airway obstruction in all dogs. CT findings indicative of laryngeal paralysis included failure to abduct the arytenoid cartilages, narrowed rima glottis, and air‐filled laryngeal ventricles. Laryngeal collapse findings depended on the grade of collapse and included everted laryngeal saccules, collapse of the cuneiform processes and corniculate processes, and narrowed rima glottis. Trachea abnormalities included hypoplasia, stenosis, or collapse syndrome. The CT findings in tracheal hypoplasia consisted of a severely narrowed lumen throughout the entire length. Tracheal stenosis was represented by a circumferential decrease in tracheal lumen size limited to one region. Tracheal collapse syndrome was diagnosed by severe asymmetric narrowing. Lobar bronchi collapse appeared in CT images as a narrowed asymmetric lumen diameter. CT imaging of unanesthetized dogs with upper airway obstruction compares favorably with traditional definitive diagnostic methods.     

Laryngeal paralysis in dogs: An evaluation of the bilateral arytenoid lateralisation procedure

Within the past decade, the number of reported cases of laryngeal paralysis in dogs has increased markedly. The disease is characterised by laryngeal obstruction caused by the inadequate abduction and instability of the arytenoid cartilages, aryepiglottic folds and vocal cords. Therefore, surgery performed to alleviate the clinical signs should ideally aim to reduce the airway obstruction and to prevent dynamic collapse. This paper presents the effectiveness of bilateral arytenoid lateralisation in 19 dogs with bilateral laryngeal paralysis. The procedure was effective in alleviating the clinical signs of laryngeal obstruction in all 19 dogs, with most surviving for several years. Postoperative laryngoscopic observations showed that the arytenoid cartilages were held in a satisfactory abducted position. A comparison of PaO₂ values before and after surgery demonstrated a significant (P 0·001) fall in the PaO₂ measurement between the pre- and postoperative blood samples. Postoperative complications included suture prosthesis failure in two dogs and a single non-fatal incident of aspiration pneumonia in two dogs.     

Complications and Long-term Results after Partial Laryngectomy for the Treatment of Idiopathic Laryngeal Paralysis in 45 Dogs

Forty-five dogs with severe respiratory signs caused by idiopathic, acquired laryngeal paralysis were treated by partial laryngectomy. The predominant postoperative complications were coughing in 28 dogs and pneumonia in 15 dogs. Eight dogs required a second operation to alleviate persistent or recurrent upper airway obstruction. Results of surgery were considered excellent in 11 dogs (25%), good in 18 dogs (40%), fair in 6 dogs (13%), and poor in 10 dogs (22%). Poorer results were obtained by surgical residents than by more experienced surgeons. Death in the immediate postoperative period was related to pneumonia (8 dogs) and laryngeal collapse (1 dog). Nine dogs died later of respiratory disease. Although partial laryngectomy is effective for the treatment of laryngeal paralysis, it is not recommended because of the high incidence of postoperative complications.     

COMPUTED TOMOGRAPHY OF NONANESTHETIZED CATS WITH UPPER AIRWAY OBSTRUCTION

Upper airway obstruction is a potentially life‐threatening problem in cats and for which a noninvasive, sensitive method rapid diagnosis is needed. The purposes of this prospective study were to describe a computed tomography (CT) technique for nonanesthetized cats with upper airway obstruction, CT characteristics of obstructive diseases, and comparisons between CT findings and findings from other diagnostic tests. Ten cats with clinical signs of upper airway obstruction were recruited for the study. Four cats with no clinical signs of upper airway obstruction were recruited as controls. All cats underwent computed tomography imaging without sedation or anesthesia, using a 16‐slice helical CT scanner and a previously described transparent positional device. Three‐dimensional (3D) internal volume rendering was performed on all CT image sets and 3D external volume rendering was also performed on cats with evidence of mass lesions. Confirmation of upper airway obstruction was based on visual laryngeal examination, endoscopy, fine‐needle aspirate, biopsy, or necropsy. Seven cats were diagnosed with intramural upper airway masses, two with laryngotracheitis, and one with laryngeal paralysis. The CT and 3D volume‐rendered images identified lesions consistent with upper airway disease in all cats. In cats with mass lesions, CT accurately identified the mass and location. Findings from this study supported the use of CT imaging as an effective technique for diagnosing upper airway obstruction in nonanesthetized cats.     

An experimental evaluation of castellated laryngofissure and bilateral arytenoid literalisation for the relief of laryngeal paralysis in dogs

The aim of this study was to compare the efficacy of 2 surgical procedures for providing an adequate laryngeal airway in dogs after surgically induced laryngeal paralysis. The laryngeal function of 10 healthy, adult experimental dogs was assessed by clinical examination, laryngoscopy, arterial blood gas measurement and analysis of tidal breathing flow-volume loops before, and after, bilateral recurrent laryngeal neurectomy. A castellated laryngofissure with vocal fold resection was done on 5 dogs and bilateral arytenoid cartilage lateralisation performed on the remaining 5 dogs. Six weeks later, the laryngeal function of the 10 dogs was reassessed, before the dogs were killed and a necropsy performed. The visible changes in laryngeal structure were recorded. Both surgical procedures alleviated some of the airway obstruction caused by the bilateral recurrent laryngeal neurectomy, but bilateral arytenoid cartilage lateralisation produced more consistent clinical improvement, a wider rima glottidis, increased inspiratory air flow and a significant increase in post-operative arterial oxygen tension.     

Pattern of breathing in brachycephalic dogs

The pattern of breathing was assessed in 19 brachycephalic dogs, using tidal breathing flow-volume loop (TBFVL) analysis. Fifteen dogs had TBFVL consistent with a fixed-type upper airway obstruction, whereas 4 dogs had a TBFVL indicative of a nonfixed upper airway obstruction. The dogs did not have a TBFVL shape the same as that considered normal for healthy nonbrachycephalic dogs. Tidal breathing flow-volume loops from brachycephalic dogs that were considered to have a normal respiratory tract (n = 11) were similar to those of dogs with clinical signs of upper airway obstruction (n = 8). Respiration was monitored continuously for short periods (20 to 50 minutes) in 3 brachycephalic dogs resting in a cage in a quiet, darkened laboratory; 2 of these dogs had periodic breathing patterns characterized by multiple episodes of alternating hypopnea and arousal. Brachycephalic dogs may be at risk for the development of disordered breathing during sleep.     

Effect of laryngoplasty on respiratory noise reduction in horses with laryngeal hemiplegia

REASONS FOR PERFORMING STUDY: Laryngoplasty is the technique of choice for treatment of laryngeal hemiplegia, with the aim of improving airway function and/or eliminating respiratory noise. However, there are no quantitative data in the literature describing the effect of laryngoplasty on upper airway noise or its relationship to upper airway mechanics in horses with laryngeal hemiplegia. OBJECTIVES: To determine whether laryngoplasty reduces respiratory noise in exercising horses with laryngeal hemiplegia; and to establish whether the degree of upper airway obstruction can be predicted by upper airway noise, or the degree of arytenoid abduction correlated with airway obstruction and noise production. METHODS: Six Standardbred horses with normal upper airways during maximal exercise were used. Respiratory sounds and inspiratory transupper airway pressure (Pui) were measured in all horses before and after induction of laryngeal hemiplegia and 30, 60 and 90 days after laryngoplasty. Inspiratory sound level (SL) and the sound intensity of the 3 inspiratory formants (F1, F2 and F3, respectively) were measured using a computer-based sound analysis programme. The degree of abduction was graded by endoscopic visualisation 1, 30, 60 and 90 days post operatively. Linear regression analysis was used to determine correlations between Pui, sound indices and grades of arytenoid abduction. RESULTS: In laryngeal hemiplegia-affected horses, Pui, inspiratory SL and the sound intensity of F1, F2 and F3 were significantly increased. At 30 days following laryngoplasty, the sound intensity of F1 and Pui returned to baseline values. The sound intensities of F2, F3 and SL were significantly improved from laryngeal hemiplegia values at 30 days post operatively, but did not return to baseline at any measurement period. Sound level, F2 and F3 were significantly correlated with Pui (P<0.05), but the correlations were weak (r2 = 0.26, 035 and 0.40, respectively). Grade of abduction and F2 were positively and significantly correlated (P<0.006, r2 = 0.76). Grade of arytenoid abduction and Pui were not correlated (P = 0.12). CONCLUSIONS: Laryngoplasty reduced inspiratory noise in laryngeal hemiplegia-affected horses by 30 days following surgery, but did not return it to baseline values. While upper airway noise and Pui were correlated, this relationship was insufficiently strong to predict Pui from noise in individual animals. The degree of arytenoid abduction was not correlated with Pui, but was positively correlated with noise production. POTENTIAL RELEVANCE: Laryngoplasty reduces upper airway noise in horses with laryngeal hemiplegia, but is not as effective as bilateral ventriculocordectomy in this regard, although respiratory noise reduction occurs more rapidly than with bilateral ventriculocordectomy. Residual noise during exercise cannot be used as a predictor of improvement in upper airway function in individual horses following laryngoplasty. The degree of arytenoid abduction obtained following surgery does not affect upper airway flow mechanics. Interestingly, we found that the greater the arytenoid abduction, the louder the respiratory noise.     

Negative Pressure Pulmonary Edema as a Post-Anesthetic Complication Associated With Upper Airway Obstruction in a Horse

An 8-year-old Trakehner mare developed fulminant pulmonary edema following suspected upper airway obstruction 50 minutes into an otherwise unremarkable anesthetic recovery after surgery for left cricoarytenoideus dorsalis muscle reinnervation and ventriculocordectomy. Establishing a patent airway by orotracheal reintubation and cardiopulmonary resuscitation attempts were unsuccessful. Gross, histological, and electron microscopic postmortem examination showed severe hemorrhagic pulmonary edema. Laryngeal swelling or hemorrhage were not evident, suggesting laryngospasm or functional airway collapse associated with the underlying left laryngeal paralysis, as a cause of the upper airway obstruction. Negative pressure pulmonary edema is rarely reported in the veterinary literature as a postanesthetic complication.     

Evaluation of unilateral arytenoid lateralization for the treatment of laryngeal paralysis in 14 cats

Laryngeal paralysis is a relatively common cause of upper airway obstruction in middle-aged to older, large-breed dogs; however, it is rare in the cat. The purpose of this study is to describe a series of cats diagnosed with laryngeal paralysis treated by unilateral arytenoid lateralization. Fourteen cats met the criteria of the study. Intraoperative and postoperative complications were seen in 21% (three of 14) and 50% (seven of 14) of cases, respectively. Median duration of follow-up was 11 months (range 3 weeks to 8 years). None of these cats had recurrence of clinical signs. Based on this brief case series, unilateral arytenoid lateralization appeared to be a suitable method for treating laryngeal paralysis in cats. Additional studies are warranted to determine the type and frequency of long-term complications.     

Results of surgical correction of abnormalities associated with brachycephalic airway obstruction syndrome in dogs in Australia

OBJECTIVES: To describe clinical features of brachycephalic airway obstructive disease in dogs, the incidence of laryngeal collapse in dogs presenting for surgery and the outcome after surgery in dogs with laryngeal collapse. METHODS: Basic clinical details were reviewed retrospectively in 73 dogs. Presence of laryngeal collapse and short-term outcomes after surgery were determined for 64 dogs with complete medical records. Long-term outcomes were reviewed for 46 dogs by telephone survey between 19 and 77 months following surgery. RESULTS: Stenotic nares were present in 31 dogs (42.5 per cent), elongated soft palate in 63 (86.3 per cent) and everted laryngeal saccules in 43 (58.9 per cent). The most common breeds were the pug (19 dogs, 26 per cent), Cavalier King Charles spaniel (15 dogs, 20.5 per cent), British bulldog (14 dogs, 19.2 per cent) and Staffordshire bull terrier (4 dogs, 5.5 per cent). Laryngeal collapse was present in 34 of 64 (53 per cent) dogs. No dogs died perioperatively and only one dog was euthanased as a result of its respiratory disease three years after surgery. Telephone interviews indicated that 26 dogs (56.5 per cent) were much improved after surgery, 15 (32.6 per cent) had some improvement and 5 (10.9 per cent) showed no improvement. Signs that persisted after surgery were snoring during sleep (34 dogs, 73.9 per cent), stertor/stridor while conscious (23 dogs, 50 per cent), excessive panting (13 dogs, 28.3 per cent) and dyspnoea (10 dogs, 21.7 per cent). Long-term outcome was considered good, even in dogs with laryngeal collapse. CLINICAL SIGNIFICANCE: Laryngeal collapse is relatively common in dogs presented for surgical correction of brachycephalic airway obstructive disease. Dogs with severe laryngeal collapse often respond well to surgery. Clinical signs rarely resolve completely following surgery.     

Laryngeal collapse in seven brachycephalic puppies

OBJECTIVES: To document the histories, clinical findings, and management of seven puppies with laryngeal collapse occurring secondarily to brachycephalic airway syndrome. METHODS: Seven brachycephalic puppies aged between 4.5 and six months underwent surgery for management of brachycephalic airway syndrome following presentation for exercise intolerance and increased respiratory noise and effort. RESULTS: Stenotic nares of varying severity and an elongated soft palate were common to all dogs. All dogs had tracheal hypoplasia and this was severe in four dogs. Laryngeal collapse was present in all dogs. Two dogs had stage I, four dogs stage II, and one dog stage III laryngeal collapse. The dog with stage III laryngeal collapse and one dog with stage II laryngeal collapse died. There was no apparent association between the changes evident on thoracic radiographs or the degree of tracheal hypoplasia and postoperative outcome. CLINICAL SIGNIFICANCE: The development of severe secondary laryngeal changes in dogs aged six months or less supports the suggestion that immature brachycephalic dogs should undergo assessment and, if indicated, surgery as soon as any clinical signs of BAS are apparent.     

Acute Upper Airway Obstruction Due to Inflammatory Laryngeal Disease in 5 Cats

Objective: To describe a clinical syndrome of upper airway obstruction in 5 cats due to inflammatory laryngeal disease.
Series Summary: Medical records of 5 cats with upper airway obstruction and a histopathologic diagnosis of inflammatory laryngeal disease were reviewed. Historical findings included: dyspnea, anorexia, voice change, and gagging/non-productive retching. Thoracic radiographs revealed a bronchial pattern in 2 cats, with consolidation of the right middle lung lobe in one cats. Laryngeal examinations typically revealed severe swelling and erythema which could not be grossly distinguished from neoplasia. Histopathologic examination of laryngeal biopsies revealed neutrophilic (n=5) and lymphoplasmacytic (n=4) inflammation. All of the cats were treated with corticosteroids and 4 cats received antibiotics. Two cats died while hospitalized, one was discharged and lost to follow-up, and 2 are doing well 7 months and 4 years later, respectively.
New information provided: Inflammatory laryngeal disease in cats may present as an acute upper airway obstruction. These cases may respond to corticosteroids and antibiotics, and some cases may have an excellent long-term prognosis.( J Vet Emerg Crit Care 2001; 11(3): 205–211 )     

Surgical relief of severe laryngeal malformation in an English Bulldog

A 22 month old English Bulldog was presented with progressive upper airway obstruction associated with an elongated soft palate, tonsillitis, everted laryngeal saccules and laryngeal malformation. Surgical management of the case consisted of resection of the elongated soft palate and everted laryngeal saccules, unilateral tonsillectomy and correction of the laryngeal stenosis. The latter was achieved by using a castellated incision through the laryngeal cartilages and first tracheal ring. From this case, it is postulated that, at least in some cases, the common upper airway obstruction syndrome in Bulldogs may not be due to laryngeal collapse as previously thought but rather to congenital malformation of the laryngeal cartilages.     

Surgical relief of severe laryngeal malformation in an English Bulldog

A 22 month old English Bulldog was presented with progressive upper airway obstruction associated with an elongated soft palate, tonsillitis, everted laryngeal saccules and laryngeal malformation. Surgical management of the case consisted of resection of the elongated soft palate and everted laryngeal saccules, unilateral tonsillectomy and correction of the laryngeal stenosis. The latter was achieved by using a castellated incision through the laryngeal cartilages and first tracheal ring. From this case, it is postulated that, at least in some cases, the common upper airway obstruction syndrome in Bulldogs may not be due to laryngeal collapse as previously thought but rather to congenital malformation of the laryngeal cartilages.     

Upper airway obstruction. General principles and selected conditions in the dog and cat

This article presents an overview of the clinical features of upper airway obstructive disorders. It includes more detailed discussions of certain common conditions such as brachycephalic airway syndrome, laryngeal paralysis, and upper airway obstruction due to trauma, foreign bodies, extraluminal masses, and tumours of the larynx and trachea.