Nebulization of epinephrine to reduce the severity of brachycephalic obstructive airway syndrome in dogs

Smoke Inhalation in Veterinary Patients: Pathophysiology, Diagnosis, and Management

Smoke contains a mixture of harmful gases, chemicals, and superheated particles. Inhalation of smoke causes generalized hypoxia and airway inflammation due to impaired oxygen transport and utilization, as well as thermal and chemical injury in the airways. Generally, treatment is supportive with oxygen therapy and airway management, including chest physiotherapy, bronchodilators, and nebulization. Immediate oxygen therapy is mandatory for all suspected smoke inhalation patients and should not be delayed pending diagnostic test results or due to "normal" oxygen saturation readings that can be falsely elevated in carbon monoxide intoxication. Smoke inhalation patients with mild clinical signs who respond well to initial stabilization generally have a favorable prognosis. However, patients with severe signs or progression despite initial stabilization may require more advanced or intensive care.

Laser-Assisted Turbinectomy in Dogs

This article discusses the laser-assisted turbinectomy (LATE) procedure and indications for its performance in dogs suffering from brachycephalic obstructive airway syndrome (BOAS). The article summarizes landmark works that reported, for the first time, endoscopic-assisted identification and treatment of structures within the brachycephalic nose that contribute to intranasal obstruction and resistance to breathing, specifically hypertrophic and aberrant nasal turbinates. Brachycephaly is discussed in the context of how these aberrations form and how definitive treatments such as LATE and adjunctive treatments such as ala vestibuloplasty, folded flap palatoplasty, and others may ameliorate the negative effects and improve patient outcomes associated with aberrant intranasal conchal configurations.

Surgical management of brachycephalic obstructive airway syndrome: An update on options and outcomes

Dogs with a brachycephalic conformation often experience a collection of abnormalities related to their craniofacial conformation, which can lead to a variety of clinical signs such as stertor, exercise intolerance, respiratory distress, and gastrointestinal signs such as regurgitation, among others. This collection of abnormalities is termed brachycephalic obstructive airway syndrome (BOAS). With the rise in popularity of several brachycephalic breeds, veterinarians and veterinary surgery specialists are seeing these dogs with increasing frequency for surgical and medical treatment of these clinical signs, leading to an increased interest in developing surgical techniques for dogs with BOAS and evaluating objective methods of determining outcome after surgery. Advances in anesthetic management including standardized protocols and use of local nerve blocks to decrease opiate use may decrease postoperative complications. A variety of new or modified surgical techniques to manage hyperplastic soft palate and stenotic nares, among other BOAS components, have been developed and studied in recent years. Newer studies have also focused on risk factors for development of major complications in the postoperative period and on objective measurements that may help determine which patients will receive the most benefit from BOAS surgery. In this review, the newest studies focused on updates in anesthetic management, surgical techniques, and postoperative care will be discussed. Additionally, updated information on complication rates and outcomes for dogs undergoing surgical management of BOAS will be included.

A retrospective observational cohort study on the postoperative respiratory complications and their risk factors in brachycephalic dogs undergoing BOAS surgery: 199 cases (2019-2021)

OBJECTIVES

To observe the occurrence of postanaesthetic respiratory complications and to determine their prevalence and risk factors in dogs undergoing brachycephalic obstructive airway syndrome surgery.

MATERIALS AND METHODS

Data from 199 clinical records were retrospectively analysed. Univariable logistic regression followed by multivariable logistic regression was used to identify associations between the dependent variables (set as the postoperative respiratory complications observed in the study dogs) and various independent covariates. The quality of model-fit was assessed using the likelihood ratio test. P≤0.05 was considered statistically significant.

RESULTS

Four postoperative respiratory complications were observed: hypoxaemia (n=10/199; 5%), dyspnoea requiring tracheal re-intubation (n=13/199, 7%), dyspnoea requiring tracheostomy (n=10/199, 5%) and aspiration pneumonia (n=12/199, 6%). Univariable logistic regression showed an association between postoperative aspiration pneumonia and increasing body condition score and American Society of Anaesthesiology classification; however, when these covariates were evaluated in the multivariable model significance was not maintained. Risk factors for tracheostomy were preoperative and postoperative aspiration pneumonia (odds ratio: 9.52, 95% confidence interval: 1.56 to 57.93) and increasing brachycephalic obstructive airway syndrome grade (odds ratio: 4.65, 95% confidence interval: 0.79 to 27.50).

CLINICAL SIGNIFICANCE

High brachycephalic obstructive airway syndrome grade and aspiration pneumonia, either developing peri-operatively or as pre-existing condition, may represent risk factors for postoperative tracheostomy. Preoperative diagnosis of aspiration pneumonia may further increase the risk of postoperative complications.

Nebulised adrenaline in the post-operative management of brachycephalic obstructive airway syndrome in dogs: short-term outcomes in 90 cases (2014-2020)

CASE HISTORIES

Medical records from a single UK-based referral hospital were retrospectively reviewed to identify brachycephalic dogs who had undergone corrective airway surgery and were nebulised with adrenaline in the post-operative period. Ninety dogs were identified between August 2014 and March 2020.

CLINICAL FINDINGS

Agitation following nebulisation with adrenaline was uncommon, with 86/90 (96%) dogs remaining calm, and overall outcome was reported as satisfactory in 68 of 73 (89%) dogs for which this information was available. Median respiratory rate at T0 (prior to first nebulisation) and T60 (1 hour following nebulisation) were both 20 breaths/minute with a median difference of 0 (95% CI = 0-0) breaths/minute (p = 0.657). Median heart rate at T0 and T60 were both 80 beats/minute with a median difference of 3 (95% CI = -10 to 7) beats/minute (p = 0.948). Two dogs experienced tachycardia, but this was not associated with the timing of administration of adrenaline. Complications reported in the 24 hours following surgery included regurgitation (n = 36), increased respiratory noise and effort (n = 10), aspiration pneumonia (n = 4), and inappetence (n = 3). A temporary tracheostomy tube was placed in 13 (14.4%) dogs.

CLINICAL RELEVANCE

Nebulisation with adrenaline is feasible, results in minimal increases in respiratory rate and heart rate and is associated with agitation in only a small number of dogs.

Challenges of transsphenoidal pituitary surgery in severe brachycephalic dogs

Introduction

Transsphenoidal hypophysectomy is the standard surgical technique for the excision of pituitary neoplasms. Anatomy may be more obscured in brachycephalic skull types due to the crowding of soft tissue and osseous structures. We describe the unique challenges to approach the sphenoid bone and localize the correct burr hole site in severe brachycephalic dogs.

Materials and methods

A single institution retrospective case series of brachycephalic dogs with pituitary-dependent hypercortisolism (PDH). Preoperative computed tomography enabled 3D-, and cross-sectional reconstruction to plan and dry-practice the position of the ideal burr hole in relation to the sella turcica, pterygoid hamular processes, and hard palate. Rostral burring of the caudal hard palate obscuring the direct sphenoid approach necessitated adaptations to the original transsphenoidal hypophysectomy procedure. Postoperative outcomes and complications with respect to those seen in mesocephalic dogs are described.

Results

Ten brachycephalic dogs including French Bulldogs (n = 9) and a single Dogue de Bordeaux were included. All dogs were diagnosed with PDH and had preoperative advanced imaging performed on the skull. All but one dog had an enlarged pituitary gland, with a median pituitary/brain value of 0.5 (range 0.21-0.9). A total of 11 transsphenoidal hypophysectomy procedures were performed in these 10 dogs. Rostral extension of the soft palate incision into the hard palate was performed to access the burr hole site on the sphenoid bone. Major complications included aspiration pneumonia (n = 1), severe gastroesophageal reflux (n = 1), and central nervous signs (=1). All dogs survived until discharge, with a median time to follow-up of 618 days (range 79-1,669 days). Seven dogs experienced long-term remission of PDH.

Conclusion

Brachycephalic dogs undergoing transsphenoid al hypophysectomy benefit from meticulous presurgical planning and extension of the approach into the caudal hard palate. Advanced surgical skills can render a good outcome in a technically challenging environment.