Quantification of nasal airflow resistance in English bulldogs using computed tomography and computational fluid dynamics

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.

The mobility of the brachycephalic canine nostril in relation to the degree of nostril stenosis

Previous studies have shown that the most reliable external conformational risk factor of whether a brachycephalic dog will develop Brachycephalic Obstructive Airway Syndrome (BOAS) is the status of nostril stenosis, assessed as a static observation using the brachycephalic nostril grading scheme. The nostrils however are a dynamic structure, opening further when the dog is exercising, sniffing or panting. The hypothesis of this study was that brachycephalic dogs with open or mildly stenotic nostrils are more likely to have nostril mobility whilst dogs with moderately or severely stenotic nostrils are more likely to have immobile nostrils. A retrospective study of dogs presented for BOAS assessment at two UK referral centres between 2012 and 2020 was performed. Data extracted included nares stenosis status and nares mobility. A mesocephalic pilot control group was recruited from a third referral centre. Statistical analysis was performed with χ2, Cochran-Armitage, spearman's rho and linear-by-linear tests as appropriate. Of the 974 brachycephalic dogs included in the study: 124 had open nostrils (68.5% mobile); 212 mildly stenotic nostrils (58.5% mobile); 379 moderately stenotic nostrils (35% mobile) and 259 severely stenotic nostrils (19.3% mobile). The nostril stenotic status was significantly associated with nostril wing mobility (χ2 =135.55; P<0.0001). When considering open and mildly stenotic (considered acceptable) nostrils versus moderate and severely stenotic nostrils, mobility was 62% versus 25.5% (χ2= 135.88; P = <0.0001). All 27 mesocephalic dogs had nostril mobility. Brachycephalic dogs with moderate and severely stenotic nares have reduced nasal mobility compared to brachycephalic dogs with mildly stenotic and open nares. Data is further evidence that dogs with moderately and severely stenotic nares should not be bred.

The effect of the surgical treatment of brachycephalic obstructive airway syndrome on the thermoregulatory response to exercise in French bulldogs: a pilot study

Introduction

Due to altered anatomy of the upper respiratory tract, brachycephalic dogs exhibit increased airway resistance and reduced surface area for evaporative heat loss, predisposing them to respiratory and thermoregulatory problems, a syndrome referred to as Brachycephalic Obstructive Airway Syndrome (BOAS). Compared to non-brachycephalic dogs, brachycephalic breeds are more susceptible to heat-related injuries even at low ambient temperatures and relatively low physical activity levels. Surgical treatment alleviates clinical signs, potentially improving dogs' thermoregulatory ability with BOAS. Our study aimed to investigate the thermoregulatory response in French bulldogs before and after the surgical correction of BOAS, respectively.

Methods

Thirteen dogs were exposed to dynamic exercise on a treadmill and the dynamics of their rectal temperature (RT) and heart rate (HR) was measured. The experiment was performed in two independent sessions, before and after the surgical treatment. The test consisted of two consecutive 5-min walks at a speed of 2.5 km/h, first at an inclination of 0% and the second at an inclination of 5%, and a 30-min recovery period. Rectal temperature and HR were measured before the start of the test (t0), at the end of the first (t1) and the second part (t2), and 15 min (t3) and 30 min (t4) in the recovery.

Results

A significant increase in RT and HR was observed during exercise and recovery compared to the resting values, implying that the exercise intensity was sufficient to challenge the thermoregulatory response. The increase of RT was significantly lower during both parts (t1: p  = 0.004; t2: p  <  0.001) of exercise after the surgical treatment than before the treatment. Although a trend of lower RT after recovery was observed compared to before the surgery, it did not reach statistical significance. Similarly to RT, the HR was significantly lower during exercise after the first (p  =  0.020) and the second part (p  =  0.011) of exercise after the surgery compared to before the surgery but did not reach significance in the recovery.

Conclusion

Surgical treatment of BOAS can improve thermoregulation during exercise in French bulldogs with BOAS.

Computational fluid dynamics comparison of the upper airway velocity, pressure, and resistance in cats using an endotracheal tube or a supraglottic airway device

Intoduction

In veterinary medicine, airway management of cats under general anesthesia is performed with an endotracheal tube (ETT) or supraglottic airway device (SGAD). This study aims to describe the use of computational fluid dynamics (CFD) to assess the velocities, pressures, and resistances of cats with ETT or SGAD.

Methods

A geometrical reconstruction model of the device, trachea, and lobar bronchi was carried out from computed tomography (CT) scans that include the head, neck, and thorax. Twenty CT scans of cats under general anesthesia using ETT (n = 10) and SGAD (n = 10) were modeled and analyzed. An inspiratory flow of 2.4 L/min was imposed in each model and velocity (m/s), general and regional pressures (cmH2O) were computed. General resistance (cmH2O/L/min) was calculated using differential pressure differences between the device inlet and lobar bronchi. Additionally, regional resistances were calculated at the device's connection with the breathing circuit (region A), at the glottis area for the SGAD, and the area of the ETT exit (bevel) (region B) and the device itself (region C).

Results

Recirculatory flow and high velocities were found at the ETT's bevel and at the glottis level in the SGAD group. The pressure gradient (Δp) was more enhanced in the ETT cases compared with the SGAD cases, where the pressure change was drastic. In region A, the Δp was higher in the ETT group, while in regions B and C, it was higher in the SGAD group. The general resistance was not statistically significant between groups (p = 0.48). Higher resistances were found at the region A (p = <0.001) in the ETT group. In contrast, the resistance was higher in the SGAD cases at the region B (p = 0.001).

Discussion

Overall, the provided CT-based CFD analysis demonstrated regional changes in airway pressure and resistance between ETT and SGAD during anesthetic flow conditions. Correct selection of the airway device size is recommended to avoid upper airway obstruction or changes in flow parameters.

Nasal anatomy and sniffing in respiration and olfaction of wild and domestic animals

Animals have been widely utilized as surrogate models for humans in exposure testing, infectious disease experiments, and immunology studies. However, respiratory diseases affect both humans and animals. These disorders can spontaneously affect wild and domestic animals, impacting their quality and quantity of life. The origin of such responses can primarily be traced back to the pathogens deposited in the respiratory tract. There is a lack of understanding of the transport and deposition of respirable particulate matter (bio-aerosols or viruses) in either wild or domestic animals. Moreover, local dosimetry is more relevant than the total or regionally averaged doses in assessing exposure risks or therapeutic outcomes. An accurate prediction of the total and local dosimetry is the crucial first step to quantifying the dose-response relationship, which in turn necessitates detailed knowledge of animals' respiratory tract and flow/aerosol dynamics within it. In this review, we examined the nasal anatomy and physiology (i.e., structure-function relationship) of different animals, including the dog, rat, rabbit, deer, rhombus monkey, cat, and other domestic and wild animals. Special attention was paid to the similarities and differences in the vestibular, respiratory, and olfactory regions among different species. The ventilation airflow and behaviors of inhaled aerosols were described as pertinent to the animals' mechanisms for ventilation modulation and olfaction enhancement. In particular, sniffing, a breathing maneuver that animals often practice enhancing olfaction, was examined in detail in different animals. Animal models used in COVID-19 research were discussed. The advances and challenges of using numerical modeling in place of animal studies were discussed. The application of this technique in animals is relevant for bidirectional improvements in animal and human health.

Ala vestibuloplasty improves cardiopulmonary and activity-related parameters in brachycephalic cats

OBJECTIVE

To evaluate the effects of ala vestibuloplasty on cardiopulmonary and lifestyle-related parameters in brachycephalic (BC) cats.

STUDY DESIGN

Prospective cohort.

ANIMALS

Client-owned BC cats (n = 19).

METHODS

Cats were assessed preoperatively by airway computed tomography (CT), endoscopy, contrast echocardiography, cardiac biomarkers, and structured owner questionnaire. Ala vestibuloplasty was performed bilaterally, and blood values, imaging, and owner questionnaire responses were re-evaluated 8-20 weeks postoperatively.

RESULTS

Cats were presented for predominantly respiratory clinical signs attributable to brachycephaly. Preoperatively, all cats had stenotic nares, prolonged normalized pulmonary transit time (nPTT) (mean 5.43 ± 1.10 s), and a hyperattenuating pulmonary pattern. No complications occurred following surgery. Postoperatively, nPTT (mean 3.89 ± 0.74 s, p < .001) and frequencies of sneezing (p = .002), snoring (p = .006), open-mouth breathing (p = .0004), and nasal discharge (p = .019) were decreased. Cats exhibited increased activity (p = .005), less frequent dyspnea during activity (p < .001), longer duration of activity before becoming dyspneic (p = .002), faster recovery from activity (p < .001), and decreased respiratory noise (p < .001). Median questionnaire scores improved from preoperative to postoperative (p < .001).

CONCLUSION

Anatomic, echocardiographic, and CT changes were common in this cohort of clinically affected BC cats. Pulmonary blood flow and respiratory function were improved after surgery.

CLINICAL SIGNIFICANCE

Stenotic nares are the predominant airway abnormality in BC cats. Ala vestibuloplasty is a safe procedure that improves cardiac and CT abnormalities and respiratory and other clinical signs in BC cats.

In-silico decongested trial effects on the impaired breathing function of a bulldog suffering from severe brachycephalic obstructive airway syndrome

BACKGROUND AND OBJECTIVE

Brachycephalic obstructive airway syndrome (BOAS) susceptible dogs (e.g., French bulldog), suffer health complications related to deficient breathing primarily due to anatomical airway geometry. Surgical interventions are known to provide acceptable functional and cosmetic results; however, the long-term post-surgery outcome is not well known. In silico analysis provides an objective measure to quantify the respiratory function in postoperative dogs which is critical for successful long-term outcomes. A virtual surgery to open the airway can explore the ability for improved breathing in an obstructed airway of a patient dog, thus supporting surgeons in pre-surgery planning using computational fluid dynamics.

METHODS

In this study five surgical interventions were generated with a gradual increment of decongested levels in a bulldog based on computed tomography images. The effects of the decongested airways on the breathing function of a patient bulldog, i.e., airflow characteristics, pressure drop, wall shear stress, and air-conditioning capacity, were quantified by benchmarking against a clinically healthy bulldog using computational fluid dynamics (CFD) method.

RESULTS

Our findings demonstrated a promising decrease in excessive airstream velocity, pressure drop, and wall shear stress in virtual surgical scenarios, while constantly preserving adequate air-conditioning efficiency. A linear fit curve was proposed to correlate the reduction in the pressure drop and decongested level.

CONCLUSIONS

The in silico analysis is a viable tool providing visual and quantitative insight into new unexplored surgical techniques.

Assessment of Nasal Structure Using CT Imaging of Brachycephalic Dog Breeds

The response to treatment of brachycephalic airway syndrome (BAS) varies among brachycephalic dog breeds. We hypothesized that variations in nasal structure are one of the factors responsible for this difference. To confirm this variation, we measured the ratio of the airway cross-sectional area to the total nasal cavity area (AA/NC) in three brachycephalic dog breeds. Head CT images of French bulldogs, shih tzus, and pugs were retrospectively collected. Four specific transverse planes were used to calculate AA/NC ratios. Fifty brachycephalic dogs were included in the study: French bulldogs (n = 20), shih tzus (n = 20), and pugs (n = 10). The AA/NC ratio of Shih Tzus was larger in the rostral nasal cavity and smaller toward the caudal area, whereas the other two breeds showed an inverse tendency. The results obtained from the current research indicate that the AA/NC ratio can be used to evaluate the structure of the nasal cavity. Moreover, analyzing the point with the smallest AA/NC ratio can be useful in quantifying nasal airway obstruction and the severity of BAS. These results will be useful in understanding the complexity of BAS pathophysiology and in the implementation of treatment.

Variations in facial conformation are associated with differences in nasal microbiota in healthy dogs

BACKGROUND

Extrinsic and intrinsic factors have been shown to influence nasal microbiota (NM) in humans. Very few studies investigated the association between nasal microbiota and factors such as facial/body conformation, age, and environment in dogs. The objectives are to investigate variations in NM in healthy dogs with different facial and body conformations. A total of 46 dogs of different age, living environment and from 3 different breed groups were recruited: 22 meso-/dolichocephalic medium to large breed dogs, 12 brachycephalic dogs and 12 terrier breeds. The nasal bacterial microbiota was assessed through sequencing of 16S rRNA gene (V1-V3 regions) amplicons.

RESULTS

We showed major differences in the NM composition together with increased richness and α-diversity in brachycephalic dogs, compared to meso-/dolichocephalic medium to large dogs and dogs from terrier breeds.

CONCLUSION

Healthy brachycephalic breeds and their unique facial conformation is associated with a distinct NM profile. Description of the NM in healthy dogs serves as a foundation for future researches assessing the changes associated with disease and the modulation of NM communities as a potential treatment.

Computational fluid dynamics comparison of impaired breathing function in French bulldogs with nostril stenosis and an examination of the efficacy of rhinoplasty

BACKGROUND

Brachycephalic obstructive airway syndrome (BOAS) in dogs indicates a particular set of upper airway abnormalities found in brachycephalic dogs (e.g., French bulldogs). Stenotic nares is one of the primary BOAS-related abnormalities restricting the functional breathing of affected dogs. For severe stenosis, rhinoplasty is required to increase the accessibility of the external nostril to air; however, the specific improvement from surgery in terms of respiratory physiology and uptake of inhaled air has not been fully elucidated METHOD: This study employed Computational Fluid Dynamics (CFD) simulations to evaluate the effects of different stenotic intensities on airflow patterns in a total of eight French bulldog upper airways. A bulldog with severe stenosis after surgery was included to examine the efficacy of the surgical intervention.

RESULTS

The results showed homogeneous airflow distributions in healthy and mild stenosis cases and significantly accelerated airstreams at the constricted positions in moderate and severe stenosis bulldogs. The airflow resistance was over 20-fold greater in severe stenosis cases than the healthy cases. After surgery, a decrease in airflow velocity was observed in the surgical region, and the percentage of reduced airflow resistance was approximately 4%.

CONCLUSIONS

This study suggests impaired breathing function in brachycephalic dogs with moderate and severe stenosis. The results also serve as a reference for veterinarians in surgical planning and monitoring bulldogs' recuperation after surgery.

Influence of computed tomographic dimensions of the nasopharynx on middle ear effusion and inflammation in pugs and French bulldogs with brachycephalic airway syndrome

OBJECTIVE

To compare the prevalence of middle ear abnormalities in pugs and in French bulldogs and evaluate the influence of nasopharyngeal dimensions on middle ear effusion.

STUDY DESIGN

Retrospective study.

ANIMALS

Thirty pugs and 30 French bulldogs with brachycephalic airway syndrome and no known history of ear disease.

METHODS

Computed tomographic (CT) studies were reviewed for middle ear effusion, mucosal contrast enhancement, signs of osteitis, and tympanic wall thickness. Soft palate thickness and cross-sectional areas of the nasopharynx at the opening of the auditory tube were measured and normalized to each individual's skull index before statistical comparison between breeds. Statistical dependence of middle ear abnormalities and nasopharyngeal dimensions was assessed by using Spearman's rank correlation tests.

RESULTS

Middle ear effusion was observed in 17 of 30 (56.7%) French bulldogs and five of 30 (16.7%) pugs. Contrast enhancement of the tympanic bulla was noted in 25 of 60 (41.6%) French bulldog ears and three of 60 (5.0%) pug ears. The cross-sectional airway dimensions (difference [Δ] = 0.31 cm² , P < .0001) and soft palate thickness (Δ = 0.44 cm, P < .0001) were reduced in pugs compared with in French bulldogs. Weak correlations were detected between soft palate thickness and nasopharyngeal dimensions and presence of tympanic bulla effusion (r = 0.324 and r = 0.198, respectively) or contrast enhancement (r = 0.270 and r = 0.199, respectively).

CONCLUSION

Middle ear effusion and inflammation were more common in French bulldogs than in pugs and did not seem related to nasopharyngeal dimensions.

CLINICAL SIGNIFICANCE

French bulldogs with brachycephalic airway syndrome seem predisposed to middle ear effusion and inflammation.

Radiographic tracheal dimensions in brachycephalic breeds before and after surgical treatment for brachycephalic airway syndrome

The objective of this retrospective study was to compare preoperative and postoperative tracheal measurements in brachycephalic dogs undergoing surgical treatment of brachycephalic airway syndrome (BAS) using 2 radiographic methods (TD:TI and TT:3R). Medical records of 24 brachycephalic dogs with surgically corrected BAS were reviewed. Represented breeds included English bulldogs (n = 9), French bulldogs (n = 9), pugs (n = 5), and a Japanese chin (n = 1). Dogs with BAS that had postoperative thoracic radiographs ≤ 1 week after surgery showed no significant difference in the mean TD:TI ratios (P = 0.06) or mean TT:3R ratios (P = 0.19) when comparing preoperative to postoperative ratios. Dogs that had postoperative thoracic radiographs > 1 week after surgery showed no significant difference in the mean TD:TI ratios (P = 0.06) or mean TT:3R ratios (P = 0.32) when comparing preoperative to postoperative ratios. According to these findings, surgical correction for BAS does not resolve or improve tracheal hypoplasia in brachycephalic breeds.

Dorsal offset rhinoplasty for treatment of stenotic nares in 34 brachycephalic dogs

OBJECTIVE

To describe the technique, outcome, and owner satisfaction associated with dorsal offset rhinoplasty (DOR) to treat stenotic nares in brachycephalic dogs.

STUDY DESIGN

Retrospective case series.

ANIMALS

Thirty-four client-owned dogs.

METHODS

Medical records of dogs treated with DOR at a veterinary teaching hospital over a 6-year period were identified. Dorsal offset rhinoplasty was defined as removal of a dorsal wedge of nasal planum from each naris with apposition of the rostral abaxial tissue to the caudal axial tissue, resulting in translocation of the alar cartilage in both median and dorsal planes. Immediate and postoperative complications were recorded. Owners were asked to report any complications with healing of the nares and to score their satisfaction with the appearance of the nares.

RESULTS

Thirty-four dogs met the inclusion criteria. Twenty-nine (85%) dogs were examined a median of 402.5 days (range, 23-2042) postoperatively, with no major complications related to the rhinoplasty recorded. Eighteen owners responded a median of 701 days (range, 37-1622) postoperatively. One owner reported that self-trauma led to collapse of one naris. One owner reported collapse of both nares within 4 years; timing and cause were unknown. Sixteen of 17 responding owners reported that they were very satisfied with the outcome of the rhinoplasty. The owner of the dog with the collapsed naris was very unsatisfied. One owner did not provide a satisfaction score.

CONCLUSION

Owners were generally highly satisfied with DOR, and complications were uncommon.

CLINICAL SIGNIFICANCE

This report describes an alternate technique to treat stenotic nares.

Canine nasal septum deviation can be a normal variation and correlates with increasing skull indices

Nasal septal deviation has been studied in relation to nasal pathology and mass effect in dogs. The purpose of this retrospective, cross-sectional study was to compare the prevalence of nasal septal deviation in dogs with rhinitis, neoplasia, and those without nasal pathology based on the facial index, skull index, and cranial index. Computed tomographic studies of the nasal cavities of dogs performed over a 5-year period were retrospectively reviewed. This study had 233 dogs meeting the inclusion criteria with 135 dogs with no nasal pathology, 63 dogs with nasal neoplasia, and 35 dogs with rhinitis. The prevalence of nasal septal deviation, the angle, maximum distance, and longitudinal extent of deviation were recorded, as well as measurements to calculate the facial index, cranial index, and skull index. The results showed no difference in the prevalence of nasal septal deviation between dogs with nasal pathology and those without. The mean longitudinal extent of deviation and maximum distance of deviation was statistically greater for those with neoplasia compared to those with rhinitis and without nasal pathology. The longitudinal extent of deviation was inversely proportional to the cranial index, facial index, and skull index. The angle of deviation was directly proportional to the facial index and skull index. In conclusion, nasal septal deviation is an anatomic variant in different breeds of dogs with no predilection based on nasal pathology. Nasal septal deviation should be interpreted cautiously in the assessment of canine nasal disease.

Use of computational fluid dynamics to compare upper airway pressures and airflow resistance in brachycephalic, mesocephalic, and dolichocephalic dogs

Brachycephalic dog breeds are prone to breathing difficulties because of their upper airway anatomy. Several surgical techniques exist to correct anatomical pathologies and common surgical approaches aim to correct functional abnormalities in the nares and/or the soft palate. However, further research is needed to improve clinical outcomes. This study evaluated air pressure and airflow resistance in the upper airways and trachea in nine sedated, sternally recumbent dogs of different skull types (dolichocephalic, n=3; mesocephalic, n=3; brachycephalic, n=3). CT images were acquired from the nostrils to the caudal border of the lungs and geometrical reconstruction of the upper airway and trachea was performed. Analysis of computational fluid dynamics was performed using inspiratory flow adapted to bodyweight for each dog. Flow (L/min) and pressure (cmH₂O) were computed for the entire upper airway and trachea. Resistance (cmH₂O/L/min) was calculated using pressure differences between the nose, larynx, and trachea. In this pilot study, statistical comparisons were not performed. Pressure maps, airflow, and resistance were similar in dolichocephalic and mesocephalic breeds. Median pressure difference (3.76cmH₂O) and resistance (0.154cmH₂O/L/min) between the nose and larynx were numerically higher in brachycephalic dogs than in other breeds (0.45cmH₂O and 0.016cmH₂O/L/min, respectively). Median pressure difference (0.205cmH₂O) and resistance (0.009cmH₂O/L/min) between the larynx and trachea was numerically similar in all dogs, except for the English bulldog. The methodology used in this preliminary study to quantify airflow characteristics such as pressure and resistance could improve the understanding of brachycephalic obstruction airway syndrome.

The impact of tongue dimension on air volume in brachycephalic dogs

OBJECTIVE

To compare the dimensions and density of the tongue in brachycephalic and mesaticephalic dog breeds and to document the relative extents of the nasopharyngeal and oropharyngeal airways occupied by the tongue and palatal tissues.

STUDY DESIGN

Case control study.

ANIMALS

Sixteen brachycephalic dogs and 12 mesaticephalic dogs.

METHODS

The volume of the tongue was measured with computed tomography in all dogs. Cross-sectional areas of tongue, oropharynx, nasopharynx, and palatal soft tissue were evaluated at two levels, the caudal aspect of the hard palate and the level of the hamulae of the pterygoid. Density of the tongue and soft palate were measured. All variables were compared between brachycephalic and mesaticephalic dogs (P ≤ .05).

RESULTS

Absolute tongue volumes did not differ between groups, the volume of the tongue was greater in brachycephalic dogs than in mesaticephalic dogs when expressed relative to (a) body weight (median 5650, interquartile range [IQR] 4833-6522 vs median 4454, IQR 4309-4743, respectively), (b) ratio between skull length/width (70 833, IQR 62490-126 209 vs 48 064, IQR 22984-64 279, respectively), and (c) skull length (689.93, IQR 618.55-970.61 vs 460.04, IQR 288.77-561.69, respectively). The proportion of air (oropharyngeal and nasopharyngeal)/soft tissue (tongue and palatal tissue) in brachycephalic dogs was decreased by approximately 60%, and the tongue was approximately 10 times denser in brachycephalic dogs than in mesaticephalic dogs.

CONCLUSION

A relative macroglossia was detected in brachycephalic dogs along with reduced air volume in the upper airway. Tongues of brachycephalic dogs were denser than those of mesaticephalic dogs.

CLINICAL SIGNIFICANCE

The relative macroglossia in brachycephalic breeds may contribute to upper airway obstruction.