Brachycephalic Syndrome Research Articles

International congress report

The 42nd World WSAVA Congress and the 23rd FECAVA Eurocongress was hosted by the DSAVA in Copenhagen from 25–28 September. There was an in-depth look at animal health related to responsible breeding, in particular brachycephalic syndrome. One of the headline Congress events was the launch of the first global guidelines for veterinary dentistry.

Effects of manipulations to detect sliding hiatal hernia in dogs with brachycephalic airway obstructive syndrome.

To determine the influence of manipulations aimed at increasing the transdiaphragmatic pressure gradient on the gastro-esophageal junction (GEJ) of dogs with brachycephalic airway obstructive syndrome (BAOS), and to identify the manipulation that most improves the detection of GEJ abnormalities and sliding hiatal hernia (SHH) in dogs with BAOS. In vivo experimental pilot study and prospective clinical study. Five purpose-bred Beagles and 20 dogs diagnosed with BAOS. Respiratory and digestive clinical signs as well as respiratory and GEJ abnormalities were scored. The presence of SHH was investigated using radiography and endoscopy in standard conditions. Endoscopic investigation was repeated after manipulations including manual pressure on the cranial abdomen (MP), Trendelenburg position (30°), or temporary complete endotracheal tube obstruction (ETO). No SHH was detected in any normal dog under any condition. Sixty-five percent of dogs with BAOS presented with digestive clinical signs, including vomiting and/or regurgitation. SHH was observed in only one dog via radiography and was not detected via endoscopy. Manipulations during endoscopy influenced GEJ abnormalities and allowed the detection of SHH in 2 (30°), 4 (ETO), and 5 (MP) dogs, respectively. Digestive clinical signs correlated with GEJ abnormalities observed only in dogs with ETO (P = .02). Manipulations aimed at increasing the transdiaphragmatic pressure gradient during endoscopy in BAOS dogs allowed the detection of GEJ abnormalities and SHH that were not detected under standard conditions. Although MP allowed detection of SHH in more dogs than ETO, scores under MP did not correlate with digestive clinical signs. Therefore, ETO may be more accurate manipulation for the detection of GEJ abnormalities in BAOS dogs.

Computed Tomographic Findings of Adenocarcinoma of the Esophagocardia Region in a Pekingese Dog with Brachycephalic Syndrome

Computed Tomographic Findings of Adenocarcinoma of the Esophagocardia Region in a Pekingese Dog with Brachycephalic Syndrome

Assessment of computed tomography derived cricoid cartilage and tracheal dimensions to evaluate degree of cricoid narrowing in brachycephalic dogs.

The aims of this observational, analytical, retrospective study were to (i) obtain computed tomographic (CT) cricoid dimensions (height, width, and transverse-sectional area), (ii) compare the cricoid dimensions between brachycephalic and mesaticephalic breeds, and (iii) compare cricoid cartilage dimensions between dogs without and affected with brachycephalic airway syndrome. The study is important to help to further evaluate and understand the anatomical components of brachycephalic airway syndrome. Measurements were performed in 147 brachycephalic and 59 mesaticephalic dogs. The cricoid cartilage was found to be significantly more oval in Pugs and French Bulldogs compared to mesaticephalic breeds. The cricoid cartilage transverse-sectional area was smallest for the Pug and, after adjusting for weight, significantly smaller for Pugs (P<0.001), Boston Terriers (P=0.001), and French Bulldogs (P<0.001) compared to Jack Russell Terriers. The tracheal transverse-sectional area at C4 of English Bulldogs was significantly smaller than for Jack Russell Terriers (P=0.005) and Labradors (P<0.001). The cricoid cartilage transverse-sectional area:weight ratio was significantly lower in brachycephalic breeds compared to mesaticephalic breeds (P<0.001). The cricoid cartilage:trachea at C4 transverse-sectional area for brachycephalic dogs was significantly larger than for mesaticephalic dogs (<0.001), demonstrating that the trachea was the narrowest part of the airway. No significant differences were found for cricoid dimensions between dogs affected with and without brachycephalic airway syndrome. However, large individual variation was found among the brachycephalic breeds and further studies investigating the relationship between cricoid cartilage size, laryngeal collapse, concurrent tracheal hypoplasia, and/or severity of brachycephalic airway syndrome are warranted.

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

Stenotic nares, edematous intranasal turbinates, mucosal swelling, and an elongated, thickened soft palate are common sources of airflow resistance for dogs with brachycephalic airway syndrome. Surgery has focused on enlarging the nasal apertures and reducing tissue of the soft palate. However, objective measures of surgical efficacy are lacking. Twenty-one English bulldogs without previous surgery were recruited for this prospective, pilot study. Computed tomography was performed using conscious sedation and without endotracheal intubation using a 128 multidetector computed tomography scanner. Raw multidetector computed tomography data were rendered to create a three-dimensional surface mesh model by automatic segmentation of the air-filled nasal passage from the nares to the caudal soft palate. Three-dimensional surface models were used to construct computational fluid dynamics models of nasal airflow resistance from the nares to the caudal aspect of the soft palate. The computational fluid dynamics models were used to simulate airflow in each dog and airway resistance varied widely with a median 36.46 (Pa/mm)/(l/s) and an interquartile range of 19.84 to 90.74 (Pa/mm)/(/s). In 19/21 dogs, the rostral third of the nasal passage exhibited a larger airflow resistance than the caudal and middle regions of the nasal passage. In addition, computational fluid dynamics data indicated that overall measures of airflow resistance may significantly underestimate the maximum local resistance. We conclude that computational fluid dynamics models derived from nasal multidetector computed tomography can quantify airway resistance in brachycephalic dogs. This methodology represents a novel approach to noninvasively quantify airflow resistance and may have utility for objectively studying effects of surgical interventions in canine brachycephalic airway syndrome.

A novel approach to brachycephalic syndrome. 3. Isolated laser-assisted turbinectomy of caudal aberrant turbinates (CAT LATE).

To describe isolated laser-assisted turbinectomy of caudal aberrant turbinates (CAT LATE) as a new minimally invasive surgical procedure for the treatment of brachycephalic dogs with obstructing caudal aberrant turbinates (CAT). Prospective clinical study. Brachycephalic dogs (24 Pugs, 1 English Bulldog) with CAT but adequate air spaces between the lamellae of the nonobstructing ventral nasal concha. A rhinoscopically guided diode laser fiber introduced from anterior was used to dissect CAT within the nasopharyngeal meatus, while leaving the intranasal turbinates intact. Small grasping forceps were used to extract the dissected CAT from anterior or to push it through the nasopharyngeal meatus for extraction from posterior. Isolated CAT LATE was successfully performed on 32 CAT in 25 dogs. Intranasally applied xylometazoline helped shrink the ventral concha, making the approach and extraction easier. Minor bleeding was the only complication observed. It is possible to remove CAT with endoscopically applied diode-laser energy while leaving the nonobstructing ventral nasal concha intact.

Acute respiratory distress associated with a nasopharyngeal foreign body in a seven-month-old French bulldog

This report describes an acute respiratory distress due to an unusual underlying disorder in a dog of a typical breed predisposed to the brachycephalic obstructive airway syndrome. The physical examination...

Evaluation of Gastroesophageal Reflux in Anesthetized Dogs with Brachycephalic Syndrome.

Brachycephalic airway syndrome may predispose to gastroesophageal reflux (GER) because of the high negative intrathoracic pressures required to overcome conformational partial upper airway obstruction. To investigate this, 20 dogs presenting for elective correction of brachycephalic airway syndrome (cases) and 20 non-brachycephalic dogs (controls) undergoing other elective surgeries were prospectively enrolled. Dogs underwent a standardized anesthetic protocol, and esophageal pH was monitored. Signalment, body weight, historical gastrointestinal and respiratory disease, complete blood count, serum biochemical values, radiographic findings, and anesthetic and surgical time were compared between cases and controls, and dogs that did and did not have basic (pH > 7.5), acidic (pH < 4), or any GER. Controls had higher mean esophageal pH (6.3) compared to cases (5.6, P = .019), but there was no difference in % with GER (cases 60%, controls 40%, P = .34). When all dogs were evaluated, dogs with GER had increased creatinine (P = .01), % positive for esophageal fluid on radiographs (P = .05), and body weight (P = .04) compared to those without GER. GER was common in both cases and controls, and cases had lower esophageal pH; however, greater numbers are required to determine if a true difference exists in % GER.

Denervation-Associated Change in the Palatinus and Levator Veli Palatini Muscles of Dogs with Elongated Soft Palate

Muscle lesions and decreased numbers of peripheral nerve branches have been reported in the soft palates of dogs presenting with brachycephalic airway obstruction syndrome (BAOS). Myosin adenosine triphosphatase staining was employed to investigate whether muscle lesions in the elongated soft palate (ESP) of dogs with BAOS reflect the presence of denervation. Soft palates were collected from nine brachycephalic dogs during surgical intervention for BAOS and from five healthy beagle dogs as controls. In the control soft palates, myofibres with relatively uniform diameters and a random mosaic pattern of type I and II myofibres were observed in the palatinus muscle (PM), while almost all of the myofibres in the levator veli palatini muscle (LVPM) were of type II. In the ESPs, small group atrophy, large group atrophy and angular-shaped atrophy were observed in myofibres of the PM and rarely in the LVPM. Fibre type grouping and an increase in type IIC myofibres were found only in the PM. Morphometric analysis of ESPs revealed a significant increase in the number of type I and II myofibres in the PM showing atrophy or hypertrophy compared with controls. A significant increase in atrophic type II myofibres was found in the LVPM of affected dogs. Myopathy consistent with denervation was observed in the PM, but rarely in the LVPM, of ESP specimens. The results suggest that the myopathy seen in dogs with ESP may partly reflect atrophy of myofibres resulting from damage to peripheral nerve branches, with subsequent reinnervation of myofibres.

How does multilevel upper airway surgery influence the lives of dogs with severe brachycephaly? Results of a structured pre- and postoperative owner questionnaire

Brachycephalic airway syndrome in dogs is typified by a variety of anatomical abnormalities causing a diverse spectrum of clinical signs of varying intensity. This variability makes the assessment of the surgical outcome after upper airway surgery difficult. Using a structured questionnaire, the present study investigated the dog owner-perceived severity and frequency of a broad spectrum of welfare-relevant impairments 2 weeks before and 6 months after brachycephalic dogs underwent a recently developed multi-level upper airway surgery. All dogs underwent surgical treatment of stenotic nares (ala-vestibuloplasty), the nasal cavity (laser-assisted turbinectomy, LATE), the pharynx (palatoplasty and tonsillotomy), and if indicated, laryngeal surgery (laser-assisted ablation of everted ventricles and partial cuneiformectomy). Owners of brachycephalic dogs (n = 102) referred for upper airway surgery were eligible to participate.Questionnaire data from owners of 37 Pugs and 25 French bulldogs were evaluated. In all dogs, the clinical signs associated with brachycephaly improved markedly after surgery. Most encouraging was the striking reduction in life-threatening events by 90% (choking fits decreased from 60% to 5% and collapse from 27% to 3%). The incidence of sleeping problems decreased from 55% to 3%, and the occurrence of breathing sounds declined by approximately 50%. There was a marked improvement in exercise tolerance and a modest improvement in heat tolerance. Dogs with severe brachycephaly benefitted substantially from multi-level surgery, and there were particular improvements in the incidences of severe impairment and life-threatening events. However, despite the marked improvement perceived by dog owners, these dogs remained clinically affected and continued to show welfare-relevant impairments caused by these hereditary disorders.

A Novel Approach to Brachycephalic Syndrome. 2. Laser-Assisted Turbinectomy (LATE).

To introduce a new surgical procedure based on interventional, laser-assisted removal of obstructing turbinate tissue to improve endonasal airway patency in brachycephalic dogs and to confirm the short and long term results using computed tomography (CT) and rhinoscopy. Prospective clinical study. Brachycephalic dogs (n = 158; 70 Pugs, 77 French Bulldogs, 11 English Bulldogs) referred for treatment of severe respiratory distress because of brachycephalic syndrome. Computed tomography and anterior and posterior rhinoscopy were performed to evaluate endonasal obstruction. Laser-assisted turbinectomy (LATE) using a diode laser was performed as part of a multilevel surgery. Nasal conchae that were causing airway obstruction were removed. The obstructing parts of the conchae were safely and efficiently removed by LATE, shaping a patent nasal airway in all dogs. The newly developed surgical procedure involved 3 steps: turbinectomy of the (1) concha nasalis ventralis; (2) rostral aberrantly growing turbinates (RAT); and (3) caudal aberrantly growing turbinates (CAT). Complications of the procedure included transient intraoperative hemorrhage in 51 of 158 dogs (32.3%); however, a temporary tamponade was necessary in only 2/158 dogs (1.3%). After 6 months, regrowth of turbinates required resection of possibly re-obstructing tissue in 25/158 dogs (15.8%; 1 Pug and 24 French Bulldogs). LATE is an effective method for creating a patent nasal airway in brachycephalic dogs with intranasal obstruction.

Anatomical, Cardiovascular, and Blood Gas Parameters in Dogs with Brachycephalic Syndrome

Background: Brachycephalic syndrome is characterized by increased airflow resistance in upper airways due to the combinations of anatomical deformities such as stenotic nares, elongated soft palate, everted laryngeal saccules, and tracheal hypoplasia. There is little information in recent literature about assessment of anatomical, cardiovascular, and blood gases’ parameters of these animals at early stages of the syndrome. The purpose of this study was to characterize and to compare anatomical, cardiovascular, and blood gases’ parameters in young brachycephalic or dolichocephalic and mesocephalic dogs.Materials, Methods &amp; Results: Twenty brachycephalic dogs (BG) and 20 dolichocephalic and mesocephalic dogs (CG), aged up to 5 years, were included in the study. Anatomical abnormalities, systolic (SAP), mean (MAP), and diastolic (DAP) arterial blood pressure were recorded. Blood gas analysis and complete blood counts (CBC) were analyzed. Doppler echocardiography, electrocardiography, ambulatory electrocardiography, and thoracic and cervical radiographs were evaluated. The diameter of the nares in BG was lower when compared to CG (0.23 ± 0.08 versus 0.56 ± 0.05 cm, P &lt; 0.001). The SaO2 was lower (P &lt; 0.001) and MAP was higher in BG (P = 0.05). All brachycephalic dogs had sinus arrhythmia (SA), and 15 (75 %) of these showed SA higher than 20% variation between adjacent RR intervals, whereas in CG, 17 (85%) of animals presented SA and 13 (65%) of these showed SA higher than 20 % variation between adjacent RR intervals. The smallest opening of the nostril, in brachycephalic dogs, was accompanied by a lower SaO2 and higher MAP. Results of this study suggest that young brachycephalic dogs have lower SaO2 and higher MAP when compared with dolichocephalic and mesocephalic dogs.Discussion: The most relevant aspect of this survey was the confirmation that brachycephalic dogs have lower SaO2 and higher MAP when compared to non brachycephalic animals. Few studies correlate upper airway obstruction to cardiovascular and blood gas alterations. Although there were no significant differences between groups for PaO2 and AaDO2, the means for BG were lower and higher, respectively, than CG, showing that obstruction of airways may lead to lower PaO2 and higher AaDO2. In the present study, brachycephalic animals tended to have higher tHb, PCV, DAP, and MAP, and lower SaO2. Even with no significant differences between groups for tHb, PCV, and DAP, one can assume that young animals may not already have presented such alterations, but as the syndrome progresses, these types of abnormalities tend to develop. Hypoventilation results in significantly lower SaO2 in these animals, as observed in this study. All brachycephalic dogs in our study had SA and 2 (10%) showed sinus pauses of 4 s and 6 s duration, which demonstrates a stimulated vagal tone. The percentage of cervical soft tissue (CST) in brachycephalic dogs was proposed in an attempt to objectively measure the soft tissue concentrated in the neck region of these animals, which may be considered a risk factor for development of the syndrome. The CST percentage was higher in BG, probably due to the increased amount of adipose tissue in the neck of these animals, fact that can contribute to an increase in tracheal pressure and vascular resistance in the region. Therefore, alterations of brachycephalic syndrome result in significant cardiovascular and blood gas abnormalities in young brachycephalic dogs, as higher MAP and lower SaO2.

Nasopharyngeal Dimensions From Computed Tomography of Pugs and French Bulldogs With Brachycephalic Airway Syndrome.

To describe the nasopharyngeal airway dimensions of two brachycephalic breeds and to localize the area of smallest airway dimensions. Prospective, descriptive, computed tomographic imaging study. Thirty pugs and 30 French bulldogs with brachycephalic upper airway syndrome. The thickness and length of the soft palate, cross-sectional area of the airway passage dorsal to the soft and hard palates, and cross-sectional area of the frontal sinus were measured and normalized to each dog's skull index and body weight before statistical comparison between breeds. Nasopharyngeal turbinates and surrounding airway space, and a possible relationship between the canine tooth angulation and the severity of airway obstruction were assessed. Pugs had significantly smaller cross-sectional areas of the airway dorsal to the soft and hard palates than French bulldogs. In both breeds, the smallest nasopharyngeal cross-sectional areas were located dorsal to the caudal end of the soft palate. The soft palate of pugs was significantly shorter than that of French bulldogs and also significantly thinner when normalized to each dog's skull index. Pugs more commonly exhibited nasopharyngeal turbinates. Pugs had significantly smaller air-filled cavities at the location of the frontal sinus. No correlation between the nasopharyngeal dimensions and canine tooth angulation was observed. Computed tomographic assessment of the upper airway morphology showed the smallest nasopharyngeal cross-sectional areas were located dorsal to the caudal end of the soft palate in both breeds. Pugs had a smaller nasopharyngeal cross-sectional area despite smaller soft palate dimensions than French bulldogs.

Histopathologic and immunohistochemical features of soft palate muscles and nerves in dogs with an elongated soft palate.

To histologically evaluate and compare features of myofibers within the elongated soft palate (ESP) of brachycephalic and mesocephalic dogs with those in the soft palate of healthy dogs and to assess whether denervation or muscular dystrophy is associated with soft palate elongation. Soft palate specimens from 24 dogs with ESPs (obtained during surgical intervention) and from 14 healthy Beagles (control group). All the soft palate specimens underwent histologic examination to assess myofiber atrophy, hypertrophy, hyalinization, and regeneration. The degrees of atrophy and hypertrophy were quantified on the basis of the coefficient of variation and the number of myofibers with hyalinization and regeneration. The specimens also underwent immunohistochemical analysis with anti-neurofilament or anti-dystrophin antibody to confirm the distribution of peripheral nerve branches innervating the palatine myofibers and myofiber dystrophin expression, respectively. Myofiber atrophy, hypertrophy, hyalinization, and regeneration were identified in almost all the ESP specimens. Degrees of atrophy and hypertrophy were significantly greater in the ESP specimens, compared with the control specimens. There were fewer palatine peripheral nerve branches in the ESP specimens than in the control specimens. Almost all the myofibers in the ESP and control specimens were dystrophin positive. These results suggested that palatine myopathy in dogs may be caused, at least in part, by denervation of the palatine muscles and not by Duchenne- or Becker-type muscular dystrophy. These soft palate changes may contribute to upper airway collapse and the progression of brachycephalic airway obstructive syndrome.

Clinical effects of the use of a bipolar vessel sealing device for soft palate resection and tonsillectomy in dogs, with histological assessment of resected tonsillar tissue.

To investigate whether soft palate resection and tonsillectomy with a bipolar vessel sealing device (BVSD) improves clinical respiratory score. To document histopathological changes to tonsillar tissue following removal with a BVSD. Case series of 22 dogs with clinical signs of upper respiratory obstruction related to brachycephalic airway syndrome. Soft palate and tonsils were removed using a BVSD. Alarplasty and saccullectomy were also performed if indicated. A clinical respiratory score was assigned preoperatively, 24-h postoperatively and 5weeks postoperatively. Excised tonsillar samples were measured and then assessed histologically for depth of tissue damage deemed to be caused by the device. Depth of tissue damage was compared between two power settings of the device. Soft palate resection and tonsillectomy with a BVSD lead to a significant improvement in respiratory scores following surgery. Depth of tissue damage was significantly less for power setting 1 compared with power setting 2. Using power setting 1, median calculated depth of tonsillar tissue damage was 3.4mm (range 1.2-8.0). One dog experienced major complications. Soft palate resection and tonsillectomy with a BVSD led to significant improvement in clinical respiratory score.

Brachycephalic problems of pugs relevant to animal welfare

AbstractExcessive breeding for brachycephaly (fore-shortened muzzle) has led to increasing problems in pugs related to brachycephalic airway syndrome (BAS). Consequently, the German Pug Club (Deutscher Mopsclub eV; DMC) established a stress test in 2009 that must be passed for breeding and requires normalised heart and respiratory rates 15 min after having covered a distance of 1 km. In this study, 42 pugs underwent the stress test under standardised conditions. Taking into account that this exercise should not be too physically demanding for any healthy dog, the results were surprising: 14 of the pugs failed, ie a failure rate of 33.3%. In addition to the stress test, the pugs were assessed according to their heart and respiratory rates at rest, which we predicted would be associated with BAS, and in this test, 21 out of 42 pugs failed. Thus, 50.0% of the pugs were in a severely compromised physical condition. A further group of seven retropugs, ie a crossbreed of pugs with a slightly longer muzzle, was included in the study to compare brachycephalic problems. All of the retropugs passed the test, even when respiratory and heart rates at rest were considered. However, the findings may not be transferable to all retropugs because of the small sample size, so further research is needed. In summary, this study has enabled the development of recommendations for future implementation of stress tests.

Signalment, clinical presentation, concurrent diseases, and diagnostic findings in 28 dogs with dynamic pharyngeal collapse (2008-2013).

BackgroundMost information about pharyngeal collapse in dogs is anecdotal and extrapolated from human medicine. A single case report describing dynamic pharyngeal collapse in a cat has been published, but there is no literature describing this disease process in dogs.ObjectiveTo describe the signalment, clinical presentation, concurrent disease processes, and imaging findings of a population of client‐owned dogs with pharyngeal collapse.AnimalsTwenty‐eight client‐owned dogs with pharyngeal collapse.MethodsRadiology reports of dogs for which fluoroscopy of the respiratory system was performed were reviewed retrospectively. Patients with a fluoroscopic diagnosis of pharyngeal collapse were included in the study population. Data regarding clinical signs, diagnostic, and pathologic findings were evaluated.ResultsTwenty‐eight dogs met the inclusion criteria. The median age of affected patients was 6.6 years, whereas median body condition score was 7/9. The most common clinical signs were coughing (n = 20) and stertor (n = 5). In 27 of 28 cases, a concurrent or previously diagnosed cardiopulmonary disorder was detected. The most common concurrent disease processes were mainstem bronchi collapse (n = 18), tracheal collapse (n = 17), and brachycephalic airway syndrome (n = 8). Fluoroscopy identified complete pharyngeal collapse in 20 of 28 dogs.ConclusionsPharyngeal collapse is a complex disease process that likely is secondary to long‐term negative pressure gradients and anatomic and functional abnormalities. Based on the findings of this study, pharyngeal fluoroscopy may be useful diagnostic test in patients with suspected tracheal and mainstem bronchial collapse to identify concurrent pharyngeal collapse.

GENDER, WEIGHT, AND AGE EFFECTS ON PREVALENCE OF CAUDAL ABERRANT NASAL TURBINATES IN CLINICALLY HEALTHY ENGLISH BULLDOGS: A COMPUTED TOMOGRAPHIC STUDY AND CLASSIFICATION.

English Bulldogs have been reported to demonstrate abnormal growth and development of the nasal turbinates, which contribute to an increase in airway resistance and hence clinical signs of brachycephalic airway syndrome. The purpose of this prospective, cross-sectional study was to assess the prevalence and severity of caudal aberrant turbinate protrusion via CT studies of English Bulldogs with, according to the owners, none or minimal clinical signs of brachycephalic airway syndrome. An additional objective was to propose a classification scheme for describing the degree of caudal aberrant turbinate protrusion in English Bulldogs and to apply this scheme in assessing the effect of gender, weight, and age on prevalence and severity of turbinate protrusion. The nasal cavities of 40 clinically healthy English Bulldogs were examined. The prevalence of caudal aberrant turbinates in this group was 100%. Using our proposed classification scheme, Grade 1 (minimal) was detected in 7 of 40 (17.5%), Grade 2 (mild) in 28 of 40 (70%), and Grade 3 (moderate) in 5 of 40 (12.5%) English Bulldogs. No significant effect of gender, weight, and age on degree of protrusion was found. In conclusion, this study identified minimal to moderate protrusion of caudal aberrant turbinates toward the nasopharynx in all the sampled English Bulldogs, despite the absence of clinical signs of brachycephalic airway syndrome.

Pro-coagulant thromboelastographic features in the bulldog.

To determine if bulldogs develop a hypercoagulable state comparable to that observed in human patients with sleep apnoea hypopnoea syndrome. Thromboelastography was performed in 15 clinically healthy bulldogs and 24 healthy control dogs of other breeds or mixed breed lineage. Bulldogs had significantly shorter R and K times relative to control dogs. The alpha angle, maximum amplitude and overall clot strength was significantly greater in bulldogs than in controls. The largest differences between the groups were found in the maximal amplitude and overall clot strength parameters. These findings support the concept that brachycephalic syndrome promotes a hypercoagulable phenotype similar to that observed with sleep apnoea hypopnoea syndrome in humans. The large increases in maximal amplitude observed suggest platelet hyperreactivity may play an important role.

The anatomy of the dog soft palate. III. Histological evaluation of the caudal soft palate in brachycephalic neonates.

A thickened and abnormally long soft palate is mostly involved in the pathogenesis of both nasopharyngeal and oropharyngeal narrowing, affecting the respiratory activity in virtually all of the brachycephalic dogs suffering from Brachycephalic Airway Obstructive Syndrome (BAOS). The morphology of the soft palate in adult mesaticephalic and brachycephalic dogs has been previously described. In this article specimens from brachycephalic dog neonates (N=10) dead from one to 3 hr after birth of unrelated conditions were collected and histologically evaluated at three transverse levels to describe the microscopic aspect of the caudal part of the soft palate. The soft palate of neonate brachycephalic dogs was histologically characterized by a musculo-connective axis containing salivary glands and coated by a mucosal layer on both the nasopharyngeal and the oral side. Quali-quantitative features, such as thickened superficial epithelium, broad oedema of the lamina propria, mucous gland hyperplasia and diverse muscular modifications described in adult brachycephalic dogs, were not observed in the soft palate of brachycephalic neonate dogs. The lack of tissue lesions in the soft palate of newborn brachycephalic dogs further supports the hypothesis that inspiratory depression during the inspiratory phase causes chronic vibration and microtrauma, which lead to soft palate alterations in adult brachycephalic dogs starting from the earliest grade of the respiratory syndrome. Overall, this study provides baseline information for the comprehension of the pathogenesis of BAOS.