Tongue and Upper Airway Dimensions: A Comparative Study between Three Popular Brachycephalic Breeds

Evaluation of measurements for tracheal hypoplasia in French bulldogs

Tracheal narrowing may increase airflow resistance, resulting in clinical manifestations associated with brachycephalic obstructive airway syndrome (BOAS). When diagnosing tracheal hypoplasia, established values are based on measurements established for English bulldogs or non-specific "bulldog" breeds. The objective of this study was to investigate tracheal diameter ratios in French bulldogs to gain a better understanding of what would constitute tracheal hypoplasia in this breed. A retrospective observational analysis was conducted to measure the right lateral thoracic radiographs of 139 French bulldogs to investigate tracheal diameter ratios. Pulmonary disease was observed in 55/139 dogs. The mean TD:Ti for healthy French bulldogs was 0.15 (±0.02), and the mean TD:ML was 0.32 (±0.07). 44/84 dogs had a TD:Ti < 0.15 (±0.02), and 37/65 dogs had a TD:ML < 0.32 (±0.07). At least one thoracic vertebral anomaly was observed in 131/139 of evaluated French bulldogs, and sternal malformations were observed in 42/139 dogs. TD:ML showed an excellent interclass correlation between observers (ICCinter 0.9562). The listed covariables were compared for statistical significance when measuring relative tracheal ratios, and none were found. There was a statistically significant relationship between TD:Ti and sex. An objective value for tracheal hypoplasia in French bulldogs has previously not been established. The mean TD:Ti described for French bulldogs in this study is higher than that previously described in other "bulldog" populations. The mean TD:ML is similar to previously reported for non-brachycephalic and non-bulldog brachycephalic small breed dogs. The correlative relationship between TD:Ti and TD:ML was statistically significant but weak.

Salivary cortisol measurements in brachycephalic dog breeds as part of a standardized stress test

Introduction

Brachycephalic obstructive airway syndrome (BOAS) is a common condition in brachycephalic dogs, with Pugs (PG) and French Bulldogs (FB) appearing to be particularly typically affected. Objective and easy-to-perform tests are necessary to detect the disease at an early stage and to exclude dogs affected by BOAS from breeding.

Methods

The present study investigated the extent to which vital signs and salivary cortisol concentrations can be used to distinguish between healthy and BOAS-affected dogs in a standardized fitness test. A total of 57 PG, 56 FB and 27 meso- and dolichocephalic dogs were studied as control group (CG). In addition to vital signs, salivary cortisol concentrations were measured before and after the exercise test.

Results

It emerged that non-brachycephalic dogs showed a higher fitness level than brachycephalic dogs. The PG recovered significantly slower than the FB after the exercise test. In unaffected PG, cortisol levels rose significantly after the test and then fell again, in unaffected FB they fell significantly during the test. Unexpectedly, cortisol levels remained constant in BOAS affected dogs of both breeds.

Discussion

A possible explanation could be a disturbance of the pituitary-hypothalamic-adrenal axis, which could be due to the chronic stress of affected animals. This would have to be clarified in further studies. In conclusion, a submaximal fitness test may be a useful method to identify dogs suffering from BOAS as it is imperative to prevent the breeding and reproduction of affected dogs.

Awake 160-Slice Computed Tomography for Upper Airway Evaluation in 17 Dogs

This study investigated using a 160-slice multidetector computed tomography (CT) scanner for conscious image acquisition in dogs with upper airway disease, and describes findings in dogs that had previously undergone soft palate surgery. Seventeen client-owned dogs with upper airway disease were retrospectively reviewed, and classified into three groups: group I, "untreated brachycephalic obstructive airway syndrome (BOAS) patients"; group II, "previously treated BOAS patients"; and group III, "patients with respiratory disease other than BOAS". Data included signalment, clinical history, direct laryngoscopy and endoscopy findings, previous surgeries and CT findings. CT scans in group I revealed overlong and thickened soft palates in all dogs, and signs of laryngeal collapse in four dogs. Patients in group II exhibited normal soft palate lengths, while patients in group III displayed various findings such as nasopharyngeal narrowing and tracheal collapse. Upper airway examinations under general anaesthesia confirmed most CT findings. This study demonstrates the feasibility and value of conscious CT scanning for assessing upper airway diseases in dogs, providing valuable diagnostic information while eliminating the need for chemical immobilisation, thus reducing patient stress and cost. These findings offer new insight into upper airway anatomy in awake patients, especially in brachycephalic breeds, and lay a foundation for future research.

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.

Evaluation of risk factors for sleep-disordered breathing in dogs

BACKGROUND

Brachycephalic dogs display sleep-disordered breathing (SDB). The risk factors for SDB remain unknown.

OBJECTIVES

To identify risk factors for SDB. We hypothesized that brachycephaly, increasing severity of brachycephalic obstructive airway syndrome (BOAS), excess weight, and aging predispose to SDB.

ANIMALS

Sixty-three privately owned pet dogs were prospectively recruited: 28 brachycephalic and 35 normocephalic (mesaticephalic or dolicocephalic) dogs.

METHODS

Prospective observational cross-sectional study with convenience sampling. Recording with the neckband was done over 1 night at each dog's home. The primary outcome measure was the obstructive respiratory event index (OREI). Body condition score (BCS) was assessed, and BOAS severity was graded for brachycephalic dogs.

RESULTS

Brachycephaly was a significant risk factor for high OREI value (ratio of the geometric means 5.6, 95% confidence interval [CI] 3.2-9.9; P < .001) but aging was not (1.1, 95% CI 1.0-1.2; P = .2). Excess weight, defined as a BCS of over 5/9, (3.5, 95% CI 1.8-6.7; P < .001) was a significant risk factor. In brachycephalic dogs, BOAS-positive class (moderate or severe BOAS signs) was a significant risk factor (2.5, 95% CI 1.1-5.6; P = .03).

CONCLUSIONS AND CLINICAL IMPORTANCE

Brachycephaly decreases welfare in a multitude of ways, including disrupting sleep. Brachycephaly, increasing severity of BOAS and excess weight are risk factors for obstructive SDB.

CT volumetric analysis permits comparison of tongue size and tongue fat in different canine brachycephalic and mesaticephalic breeds

While macroglossia is a newly accepted component of brachycephalic obstructive airway syndrome (BOAS) in dogs, macroglossia with increased tongue fat is a well-known cause for obstructive sleep apnea (OSA) in people, and targeted reduction procedures such as midline glossectomy are used to treat people with OSA. While midline glossectomy has been described in dogs, tissue contributions to macroglossia have not been characterized. The purpose of this retrospective, descriptive, case-control study was to describe and compare volumetric dimensions of the tongue and tongue fat in brachycephalic (BC) and mesaticephalic (MC) dogs using CT images. Data collected included head and neck CT images from 17 BC and 18 control MC dogs. Multiplanar reformatted and 3D reconstructed images were created using image segmentation and specialized visualization software to calculate volumetric dimensions of the total tongue, tongue fat, and tongue muscle. Rostral and caudal topographical distributions of fat were compared. Total tongue and tongue muscle volume (P < 0.0001) and tongue fat volume (P = 0.01) normalized to body weight (BW) were greater in BC dogs. More fat was localized in the caudal tongue in both groups (P < 0.04). In regression analysis, BC conformation and increased weight were significant predictors of increased tongue fat volume. As in people, increased tongue fat may contribute to macroglossia and sleep-disordered breathing in BC dogs. Use of CT volumetry to identify tongue fat deposits may permit targeted surgical reduction of tongue volume in BC dogs and contribute substantially to treatment of BOAS.