Bronchial abnormalities found in a consecutive series of 40 brachycephalic dogs

Davide De Lorenzi San Marco Private Veterinary Clinic, Via Sorio 114/c, 35141—Padua, Italy.

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Diana Bertoncello San Marco Private Veterinary Clinic, Via Sorio 114/c, 35141—Padua, Italy.

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Michele Drigo Department of Public Health, Comparative Pathology and Veterinary Hygiene, Faculty of Veterinary Medicine, Viale dell'Università 16—35020 Legnaro (Padua), Italy.

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Abstract

Objective—To detect abnormalities of the lower respiratory tract (trachea, principal bronchi, and lobar bronchi) in brachycephalic dogs by use of endoscopy, evaluate the correlation between laryngeal collapse and bronchial abnormalities, and determine whether dogs with bronchial abnormalities have a less favorable postsurgical long-term outcome following correction of brachycephalic syndrome.

Design—Prospective case series study.

Animals—40 client-owned brachycephalic dogs with stertorous breathing and clinical signs of respiratory distress.

Procedures—Brachycephalic dogs anesthetized for pharyngoscopy and laryngoscopy between January 2007 and June 2008 underwent flexible bronchoscopy for systematic evaluation of the principal and lobar bronchi. For dogs that underwent surgical correction of any component of brachycephalic syndrome, owners rated surgical outcome during a follow-up telephone survey. Correlation between laryngeal collapse and bronchial abnormalities and association between bronchial abnormalities and long-term outcome were assessed.

Results—Pugs (n = 20), English Bulldogs (13), and French Bulldogs (7) were affected. A fixed bronchial collapse was recognized in 35 of 40 dogs with a total of 94 bronchial stenoses. Abnormalities were irregularly distributed between hemithoraces; 15 of 94 bronchial abnormalities were detected in the right bronchial system, and 79 of 94 were detected in the left. The left cranial bronchus was the most commonly affected structure, and Pugs were the most severely affected breed. Laryngeal collapse was significantly correlated with severe bronchial collapse; no significant correlation was found between severity of bronchial abnormalities and postsurgical outcome.

Conclusions and Clinical Relevance—Bronchial collapse was a common finding in brachycephalic dogs, and long-term postsurgical outcome was not affected by bronchial stenosis.

Abstract

Objective—To detect abnormalities of the lower respiratory tract (trachea, principal bronchi, and lobar bronchi) in brachycephalic dogs by use of endoscopy, evaluate the correlation between laryngeal collapse and bronchial abnormalities, and determine whether dogs with bronchial abnormalities have a less favorable postsurgical long-term outcome following correction of brachycephalic syndrome.

Design—Prospective case series study.

Animals—40 client-owned brachycephalic dogs with stertorous breathing and clinical signs of respiratory distress.

Procedures—Brachycephalic dogs anesthetized for pharyngoscopy and laryngoscopy between January 2007 and June 2008 underwent flexible bronchoscopy for systematic evaluation of the principal and lobar bronchi. For dogs that underwent surgical correction of any component of brachycephalic syndrome, owners rated surgical outcome during a follow-up telephone survey. Correlation between laryngeal collapse and bronchial abnormalities and association between bronchial abnormalities and long-term outcome were assessed.

Results—Pugs (n = 20), English Bulldogs (13), and French Bulldogs (7) were affected. A fixed bronchial collapse was recognized in 35 of 40 dogs with a total of 94 bronchial stenoses. Abnormalities were irregularly distributed between hemithoraces; 15 of 94 bronchial abnormalities were detected in the right bronchial system, and 79 of 94 were detected in the left. The left cranial bronchus was the most commonly affected structure, and Pugs were the most severely affected breed. Laryngeal collapse was significantly correlated with severe bronchial collapse; no significant correlation was found between severity of bronchial abnormalities and postsurgical outcome.

Conclusions and Clinical Relevance—Bronchial collapse was a common finding in brachycephalic dogs, and long-term postsurgical outcome was not affected by bronchial stenosis.

The precise conformation that constitutes brachycephaly has not been rigorously defined, but breeds usually considered to be brachycephalic include English and French Bulldogs, Boston Terriers, Pugs, Pekingese, and Shih Tzus.1 In all these breeds, upper airway obstruction has been described as a result of their abnormal pharyngeal and nasal anatomy as a result of rostral shortening of the skull2; stenotic nares, abnormal turbinates, and soft palate elongation and thickening are the most common components of the brachycephalic airway syndrome.3

Additional conditions that may be present in these breeds are tracheal hypoplasia; esophageal, gastric, and duodenal abnormalities; and ophthalmologic as well as dental malformations.3–5 Affected dogs may have any combination of these disorders, which can cause varying degrees of compromise of the upper respiratory tract resulting in inspiratory stertor, exercise intolerance, dyspnea, gagging, cyanosis, and syncope.3

A definitive diagnosis of upper airway obstruction is provided by pharyngoscopic and laryngoscopic examinations, which are usually performed in conjunction with surgery to relieve obstructions.6 Brachycephalic syndrome is a well-described entity, although to the best of our knowledge, abnormalities of the lower respiratory tract (trachea, principal bronchi, and lobar bronchi) have never been systematically evaluated by endoscopic inspection in these breeds. We hypothesized that as a result of dynamic and chronic obstruction of the upper respiratory tract beginning at birth, these dogs must generate large pressure changes to move air, both during inhalation and exhalation. This could cause detectable abnormalities, including bronchial and tracheal collapse, in the lower respiratory tract as described for children7 and cats8 and which have been experimentally induced in fetal and neonatal piglets.9

The purpose of the study reported here was to investigate and describe endoscopically detectable abnormalities of the lower respiratory tract in a series of client-owned brachycephalic dogs, to evaluate a possible correlation between laryngeal collapse and bronchial abnormalities, and to determine whether dogs with bronchial abnormalities have a less favorable postsurgical long-term outcome.

Materials and Methods

Animals—During the period of January 2007 to June 2008, brachycephalic dogs admitted to the San Marco Private Veterinary Clinic with a history of respiratory distress and noisy breathing were included in this study. All dogs underwent a complete endoscopic examination including pharyngoscopy, laryngoscopy, and tracheobronchoscopy. All endoscopic procedures were performed by the same investigator (DDL). The study protocol was performed in compliance with institutional guidelines for research on animals, the owners of all dogs in our study were informed about all the procedures, and we obtained signed informed consent from every owner.

Procedures—Information obtained for each dog during the preanesthetic evaluation included signalment, clinical signs at the time of admission, physical examination findings, hematologic analysis results, and findings on thoracic radiography (data not analyzed). For the endoscopic procedures, dogs were sedated with medetomidine (30 μg/kg [13.6 μg/lb], IM) and methadone (0.2 to 0.4 mg/kg [0.09 to 0.18 mg/lb], IM), and anesthesia was induced with propofol (4 mg/kg [1.8 mg/lb], IV) and maintained with sevoflurane in oxygen.

Laryngoscopy, pharyngoscopy, and cervical tracheoscopy were performed by use of a 2.7-mm rigid telescopea with a halogen light source with dogs under light sedation following IV administration of an anesthetic; bronchoscopy was performed under a consistent depth of inhalation anesthesia by passing a 2.7-mm × 100-cm fiber-optic endoscopeb through a T-adapter inserted between the tracheal tube and the tubing of the anesthesia machine. All endoscopic examinations were performed with dogs in sternal recumbency and were digitally recorded by a camerac connected to the endoscopes.

Grading systems—Laryngeal collapse was graded as proposed by Leonard.10 Stage 1 was characterized by eversion of the laryngeal saccules, stage 2 by a medial displacement of the cuneiform processes of the arytenoid cartilages, and stage 3 by a collapse of the corniculate processes of the arytenoid cartilages with loss of the dorsal arch of the rima glottis.

We adopted a standard bronchoscopic examination with the tracheobronchial anatomy nomenclature proposed by Amis and McKiernan.11 Once the tip of the bronchoscope approached the carina, each lobar bronchus was examined in the following order: left principal bronchus, left caudal lobe bronchus, left cranial ventral subsegmental bronchus, left cranial dorsal subsegmental bronchus, right principal bronchus, right cranial bronchus, right middle bronchus, right accessory bronchus, and right caudal bronchus.

Tracheal collapse was graded as proposed by Tagner and Hobson.12 Grade 1 represented a reduction of tracheal diameter up to 25%, grade 2 represented a reduction of diameter up to 50%, grade 3 represented a reduction of diameter up to 75%, and grade 4 represented total tracheal collapse with the lumen completely obliterated.

The grade of bronchial collapse was based on the diameter reduction, considering that normal bronchi have a round or slightly oval, smooth appareance.13 Grade 1 represented a diameter reduction up to 30%, grade 2 represented a diameter reduction up to 60%, and grade 3 represented a diameter reduction > 60% up to a complete bronchial collapse (100%). A score from 1 (grade 1 stenosis) to 3 (grade 3 stenosis) was assigned to each collapsed bronchus.

Digital files with images from all the procedures were independently reviewed in a blind, separate fashion. Two scorers gave an independent score for laryngeal and tracheobronchial abnormalities, and a discussion, to reach a consensus opinion, was done only in cases of divergent opinion.

Surgical outcome—Surgery included stenotic nares correction by horizontal wedge resection and resection of elongated soft palate and laryngeal saccules. For dogs that underwent surgical correction of any component of brachycephalic syndrome, telephone interviews with the owners of dogs were conducted ≥ 6 months after surgery. Owners were asked to rate the surgical outcome of their dogs as follows: poor (when the clinical situation worsened or did not improve after surgery), moderate (good improvement of the clinical situation with some limitations of physical activity after surgery), and adequate (excellent improvement in both the clinical situation and physical activity after surgery).

Statistical analysis—Analyses were performed with a commercially available software program.d Data analyses were performed to evaluate the correlation between laryngeal collapse, bronchial abnormalities (computed as the sum of the single bronchial scores), and long-term outcome, with Spearman's rank correlation coefficient. Mann-Whitney and Kruskall-Wallis nonparametric tests were used to compare laryngeal collapse and bronchial abnormalities between sexes and among breeds, respectively. A value of P < 0.05 was considered significant.

Results

The 40 brachycephalic dogs examined with noisy breathing and clinical signs of respiratory distress in the period of January 2007 to June 2008 comprised Pugs (n = 20 [50%]), English Bulldogs (13 [33%]), and French Bulldogs (7 [18%]). The study population included 25 male (1 castrated) and 15 female (2 neutered) dogs. Dogs ranged in age from 4 months to 10 years (mean age, 8.7 years; median age, 3 years). Twenty-four of the 40 (60%) dogs were ≤ 3 years old.

All examined dogs had an elongated soft palate and some degrees of stenotic nares. The grade of laryngeal collapse, number of affected dogs, and percentage distribution within each breed and within the total number of dogs were determined (Table 1). Only 1 French Bulldog had a larynx without any degree of collapse (14.3% [1/7] of all French Bulldogs and 2.5% [1/40] of all examined dogs). Only 1 dog, a 10-year-old neutered female Pug, had complete tracheal collapse (grade 4 thoracic collapse).

Table 1—

Breed distribution of grade of laryngeal collapse in 39* brachycephalic dogs.

BreedGrade 1Grade 2Grade 3
No. of affected dogsPercentage of all dogsNo. of affected dogsPercentage of all dogsNo. of affected dogsPercentage of all dogs
Pug (n = 20)37.71128.2615.4
English Bulldog (n = 13)512.8615.425.1
French Bulldog (n = 6)*410.225.100

One of the 7 French Bulldogs of this study is not represented in the table because it had no laryngeal abnormalities.

Endoscopically detectable bronchial abnormalities were recognized in 35 of 40 (87.5%) dogs. Various combinations of both grade and distribution of bronchial collapse were identified. Dogs with grade 1 collapse (score 1) had bronchi with a slightly oval shape with several regularly spaced folds in the mucosa; dogs with grade 2 collapse (score 2) had bronchi with the oval shape changed into a more flattened profile, and in some instances, deeper mucosal folds were visible; and dogs with grade 3 collapse (score 3) had bronchi in which the lumen appeared flattened along a single plane and mucosal folding was not prominent (Figure 1). Closure of the bronchial lumen appeared to occur first at a point within the lumen, while the lumen on both sides of this point was narrowed but still patent (Figure 2). In all affected dogs, the bronchial diameter did not have substantial variations during the different respiratory phases (nondynamic, fixed collapse). In general, the segmental and subsegmental bronchi examined beyond the collapsed bronchus had a normal shape and appearance.

Figure 1—
Figure 1—

Endoscopic image of the left cranial ventral subsegmental bronchus (black arrow) and left cranial dorsal subsegmental bronchus (white arrow) of a dog; the left cranial ventral subsegmental bronchus has a grade 1 collapse, while the left cranial dorsal subsegmental bronchus has a grade 3 collapse.

Citation: Journal of the American Veterinary Medical Association 235, 7; 10.2460/javma.235.7.835

Figure 2—
Figure 2—

Endoscopic image of the left main bronchus of a dog. The left main bronchus has a grade 3 collapse with almost complete bronchial closure in a flat, horizontal plane.

Citation: Journal of the American Veterinary Medical Association 235, 7; 10.2460/javma.235.7.835

The localization, grade, and breed distribution of bronchial stenoses were summarized (Table 2). Results of data analysis did not reveal any significant differences for laryngeal collapse and bronchial abnormalities with respect to sex of dogs.

Table 2—

Distribution of 94 bronchi affected by bronchial collapse as grouped by breed (Pugs [n = 20 dogs], English Bulldogs [13], and French Bulldogs [7]), grade, and localization in 40 brachycephalic dogs.

BronchusGrade 1Grade 2Grade 3Score
PugEBFBTotalPugEBFBTotalPugEBFBTotal
RPB31042002100111
RB110012103200213
RB20000000010013
RB30000000000000
RB40000100100002
LPB10013104200215
LB1V143294116800845
LB1D13115422810301360
LB2533116208400439
Total178631227332283031NA

EB = English Bulldog. FB = French Bulldog. RPB = Right principal bronchus. RB1 = Right cranial bronchus. RB2 = Right middle bronchus. RB3 = Right accessory bronchus. RB4 = Right caudal bronchus. LPB = Left principal bronchus. LB1V1 = Left cranial ventral subsegmental bronchus. LB1D1 = Left cranial dorsal subsegmental bronchus. LB2 = Left caudal lobe bronchus. NA = Not applicable.

A total of 94 bronchial stenoses (31 [32.9%] grade 1, 32 [34.0%] grade 2, and 31 [32.9%] grade 3) were detected in the 40 dogs. Abnormalities were irregularly distributed among the 2 hemithoraces with 15 of 94 (15.9%) bronchial abnormalities in the right bronchial system (5 grade 1, 6 grade 2, and 4 grade 3; right total score, 29), while 79 of 94 (84.0%) bronchial stenoses were detected in the left bronchial system (26 grade 1, 26 grade 2, and 27 grade 3; left total score, 159).

The left cranial dorsal subsegmental bronchus was the most commonly affected bronchus, with 26 of 94 (27.7%; 5 grade 1, 8 grade 2, and 13 grade 3; total score, 60) having abnormalities, while the left cranial ventral subsegmental bronchus was the second most affected bronchus with 23 of 94 (24.5%; 9 grade 1, 6 grade 2, and 8 grade 3; total score, 45) having abnormalities. In general, the left cranial bronchi (ventral and dorsal subsegmental bronchi) were the most affected structures with abnormalities detected in 49 of 94 (52.1%).

Pug was the most severely affected breed, both for laryngeal collapse (χ2 = 7.3) and bronchial abnormalities (χ2 = 19.4), followed by English Bulldog and French Bulldog. Laryngeal collapse significantly correlated with more severe bronchial collapse, as determined by the sum of the scores (Spearman's U = 0.45).

Of the 36 dogs that underwent surgery and for which follow-up information was available, 21 (58.3%) had an adequate outcome, 11 (30.6%) had a moderate outcome, and 4 (11.1%) had a poor outcome. The severity of bronchial collapse (indicated by the sum of the scores) and outcome were not correlated (Spearman's U = −0.02; P = 0.8).

Discussion

To our knowledge, this is the first study in which endoscopically detectable bronchial abnormalities are described in a series of brachycephalic dogs. While tracheal collapse was detected in only 1 dog in our study, bronchial collapse seemed to be a common finding in dogs of our study. Although the series of brachycephalic dogs in our study may have been too small to provide clinically relevant information and was biased toward dogs with clinical signs of upper airway obstruction, we found that Pugs were at particular risk of bronchial collapse. Moreover, in our study population, the leftside bronchi, particularly the cranial subsegmental branches, were significantly more often affected by this abnormality than the right-side bronchi.

We hypothesized that bronchial collapse can be caused by resistance resulting from obstruction of the upper respiratory tract, a typical feature of these breeds. Brachycephalic breeds are particularly prone to dynamic obstruction of the upper respiratory tract14 as a result of having narrow nares and redundant tissue folds in the pharynx; these obstruct the air passages so that brachycephalic dogs must generate, from birth, large pressure changes during inhalation and exhalation. During both respiratory phases, pressure gradients develop across the walls of the airways; these gradients change the diameter of the collapsible portions of the airways, thereby changing the airway resistance. Whereas dynamic airway collapse usually occurs during inhalation in the extrathoracic portion of the respiratory tract, it occurs during forced exhalation in the intrathoracic portion.15,16

In healthy dolichocephalic dogs, respiratory muscles relax during exhalation, lungs compress gas in the alveoli, and air flows out; pleural pressure during exhalation is slightly negative (subatmospheric). In brachycephalic breeds, upper airway obstruction causes resistance to air flow and a remarkable increase in the pressures in the upper respiratory tract during exhalation as a result of the use of the accessory muscles of exhalation17; as a consequence, as brachycephalic dogs make a greater effort to exhale, the pleural pressure increases well above atmospheric pressure, causing a dramatic increase in the transmural pressure across the wall of the intrathoracic portion of the respiratory tract, which then collapses.

As the airway becomes compressed, air must accelerate through the collapsed portion; according to the Bernoulli effect, the increased velocity through the narrowed bronchi leads to a further decrease in pressure within the collapsed airways and further narrowing. When brachycephalic dogs try harder to exhale, the pressures decrease more and the airway collapse increases.

If this vicious cycle of events happens in young puppies with more pliable and soft cartilages, it could go on until the bronchi have a complete, fixed collapse (Figure 2); because immature airways are highly compliant, in comparison with those of adults,9 the bronchi from young animals may be easily compressed and definitively deformed during continuous forced exhalation, as happens in brachycephalic puppies that already have stertorous breathing and snoring during their first weeks of life. The bronchi from human infants are also closed by relatively small transmural pressures, suggesting that infant airways could be more vulnerable to collapse. This may be because the cartilage plates are more pliable and bend easily under lower pressures; compression of infant airways could occur during forced exhalation, such as continuous crying or coughing,18 or during repeated attempts to clear an obstruction.19

In the dogs of our study, the left-side bronchi were generally more affected by bronchial collapse than were the right-side bronchi. The same distribution is described in infants and children with bronchial collapse.7,20 While, in our dogs, the left cranial dorsal subsegmental bronchus was the most frequently affected bronchus, with 26 (13 grade 3) stenoses detected, in infants and children, the left principal bronchus is the more common site of bronchial collapse because the left mainstem bronchus extends further without branch points than does the right mainstem bronchus, causing it to experience lower resistance to transmural pressures.7

Factors contributing to this particular distribution of bronchial collapse in our group of brachycephalic dogs are not known, though we postulate that thoracic conformation, comprising the anatomic features of individual bronchi and lung lobes, may be responsible for the predominant left-side involvement. Other likely contributing variables could be heart size in conjunction with the shape of the thoracic cavity and concurrent bronchial diseases.

Bronchial collapse could explain the predisposition of Pugs to cranial left lung lobe torsion.21–23 Lung lobe torsion is an uncommon life-threatening condition defined as the rotation of a lung lobe along its long axis with twisting of the bronchovascular pedicle at the hilus.24 Factors contributing to torsion of the left cranial lung lobe in Pugs are not known.21 We suppose that lung lobe atelectasis resulting from bronchial collapse25 may alter the spatial association among the lung lobes and may increase their mobility relative to one another, leading to lobe torsion and thus explaining the particular frequency of left cranial lung lobe torsion in this breed.

Laryngeal collapse is a common secondary change occurring in brachycephalic breeds of dogs,2,4 occurring as a result of the chronic increase in negative pressures during inhalation.17 Results of our study indicate that laryngeal collapse is a more common complication than has previously been reported3,26; overall, 39 of 40 (97.5%) dogs in our study had some degree of laryngeal collapse according to the Leonard grade system.10 Our findings are in good concordance with data reported by Torrez and Hunt.4 In their study, 13 Pugs of 46 (28.3%) brachycephalic dogs had laryngeal collapse, while in our study, Pugs with laryngeal collapse comprised 20 of 40 (50%) dogs.

In our study, we found a significant correlation between the severity of laryngeal collapse and the severity of bronchial collapse; we explain this result as a consequence of congenital abnormalities involving the nose and pharynx, causing brachycephalic puppies to require exaggerated respiratory efforts both during inhalation and exhalation, from their birth. In 1 report,2 the presence of severe secondary laryngeal collapse in a series of 7 brachycephalic puppies aged < 6 months is described; these findings indicate that severe secondary changes caused by respiratory efforts can already be present in young animals. We hypothesize that the same cause (exaggerated respiratory efforts in young animals with more pliable cartilages) is responsible both for laryngeal collapse and bronchial abnormalities, thus explaining the significant correlation between the severity of laryngeal and bronchial collapse.

Despite many reports4 regarding brachycephalic obstructive syndrome, information about the long-term prognosis after surgery is sparse. In our study, followup information was available for all dogs (36/40) that underwent surgical correction of brachycephalic airway obstruction syndrome. The long-term outcome for these dogs was better than previously reported27,28 and is similar to that in a more recent study by Riecks et al.3 Surprisingly, among our dogs, outcomes were not significantly affected by the severity of the bronchial collapse. Some recent publications regarding brachycephalic syndrome in dogs focused on the postoperative outcome in dogs with tracheal hypoplasia3 and laryngeal collapse.2,4 According to findings in a previous study,1 dogs with a hypoplastic trachea may have a less favorable prognosis than those without; Riecks et al3 demonstrated that there is no significant difference in the long-term outcome between dogs with a hypoplastic trachea and dogs with a normal tracheal diameter. The same results were detected for our dogs, in which no significant differences were found among dogs according to their bronchial defects.

The results of our study suggest that bronchial collapse is a common finding in brachiocephalic breeds and that laryngeal collapse is significantly correlated with more severe bronchial collapse, which may be the result of exaggerated respiratory efforts in young puppies with more pliable cartilages. We found no significant correlations between the severity of bronchial abnormalities and postsurgical outcomes, but we think that bronchial collapse might explain the predisposition of Pugs to cranial left lung lobe torsion. Further characterization of bronchial abnormalities in these breeds is required, and the authors recommend more anatomic, histologic, and eventually ultrastructural studies. Wider-prospective studies evaluating the contribution of collapsed bronchi to increased airway resistance as well as the real incidence and breed prevalence of these abnormalities are warranted.

a.

K Storz 64018BS telescope, Karl Storz Endoscopy, Tuttlingen, Germany.

b.

K Storz 60003VB fibroscope, Karl Storz Endoscopy, Tuttlingen, Germany.

c.

III K Storz 69236001 video CCD camera, Karl Storz Endoscopy, Tuttlingen, Germany.

d.

SPSS, version 12.0.0, SPSS Inc, Chicago, Ill.

References

  • 1.

    Hendricks JC. Brachycephalic airway syndrome. Vet Clin North Am Small Anim Pract 1992;22:11451152.

  • 2.

    Pink JJ, Doyle RS, Hughes JML, et al. Laryngeal collapse in seven brachycephalic puppies. J Small Anim Pract 2006;47:131135.

  • 3.

    Riecks TW, Birchard SJ, Stephens JA. Surgical correction of brachycephalic syndrome in dogs: 62 cases (1991–2004). J Am Vet Med Assoc 2007;230:13241328.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 4.

    Torrez CV, Hunt GB. Results of surgical correction of abnormalities associated with brachycephalic airway obstruction syndrome in dogs in Australia. J Small Anim Pract 2006;47:150154.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 5.

    Poncet CM, Dupre GP, Freiche VG, et al. Prevalence of gastrointestinal tract lesions in 73 brachycephalic dogs with upper respiratory syndrome. J Small Anim Pract 2005;46:273279.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 6.

    Hedlund CS. Brachycephalic syndrome. In: Bojrab MJ, ed. Current techniques in small animal surgery. 4th ed. Baltimore: The Williams & Wilkins Co, 1998;357362.

    • Search Google Scholar
    • Export Citation
  • 7.

    Finder JD. Primary bronchomalacia in infants and children. J Pediatr 1997;130:5966.

  • 8.

    Fujita M, Miura H, Yashuda D, et al. Tracheal narrowing secondary to airway obstruction in two cats. J Small Anim Pract 2004;45:2931.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 9.

    McFawn PK, Mitchell HW. Effect of transmural pressure on preloads and collapse of immature bronchi. Eur Respir J 1997;10:322329.

  • 10.

    Leonard HC. Collapse of the larynx and adjacent structures in the dog. J Am Vet Med Assoc 1960;137:360363.

  • 11.

    Amis TC, McKiernan BC. Systematic identification of endobronchial anatomy during bronchoscopy in the dog. Am J Vet Res 1986;47:26492657.

    • Search Google Scholar
    • Export Citation
  • 12.

    Tagner CH, Hobson HP. A retrospective study of 20 surgically managed cases of collapsed trachea. Vet Surg 1982;11:146149.

  • 13.

    Johnson L. Small animal bronchoscopy. Vet Clin North Am Small Anim Pract 2001;31:691705.

  • 14.

    Amis TC, Kurpershoek C. Tidal breathing flow-volume loop analysis for clinical assessment of airway obstruction in conscious dogs. Am J Vet Res 1986;47:10021006.

    • Search Google Scholar
    • Export Citation
  • 15.

    Macklem PT, Mead J. Factors determining maximal expiratory flow in dogs. J Appl Physiol 1968;25:159169.

  • 16.

    Wilson TA, Hyatt RE. Forced expiration. In: Cristal RG, West JB, eds. The lungs: scientific foundations. New York: Raven Press, 1991;1021.

    • Search Google Scholar
    • Export Citation
  • 17.

    Robinson NE. Airway physiology. Vet Clin North Am Small Anim Pract 1992;22:10521057.

  • 18.

    Sotomayor JL, Godinez RI, Borden S, et al. Large-airway collapse due to acquired tracheobronchomalacia in infancy. Am J Dis Child 1986;140:367371.

    • Search Google Scholar
    • Export Citation
  • 19.

    Martinez FD. Sudden infant death syndrome and small airway occlusion: facts and a hypothesis. Pediatrics 1991;87:190198.

  • 20.

    Boogaard R, Huijsmans SH, Pijnenburg MW, et al. Tracheomalacia and bronchomalacia in children: incidence and patient characteristics. Chest 2005;128:33913397.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 21.

    Murphy KA, Brisson BA. Evaluation of lung lobe torsion in Pugs: 7 cases (1991–2004). J Am Vet Med Assoc 2006;228:8690.

  • 22.

    Rooney MB, Lanz O, Monnet E. Spontaneous lung lobe torsion in two Pugs. J Am Anim Hosp Assoc 2001;37:128130.

  • 23.

    Spranklin DB, Gulikers KP, Lanz OI. Recurrence of spontaneous lung lobe torsion in a Pug. J Am Anim Hosp Assoc 2003;39:446451.

  • 24.

    Moon F, Fossum TW. Lung lobe torsion. In: Bonagura JD, ed. Kirk's current veterinary therapy XII: small animal practice. Philadelphia: WB Saunders Co, 1995;919921.

    • Search Google Scholar
    • Export Citation
  • 25.

    Aldrich J. Atelectasis. In: King LG, ed. Textbook of respiratory disease in dogs and cats. St Louis: Elsevier, 2004;465472.

  • 26.

    Lorinson D, Bright RM, White RAS. Brachycephalic airway obstruction syndrome—a review of 118 cases. Canine Pract 1997;22(5–6):1821.

    • Search Google Scholar
    • Export Citation
  • 27.

    Harvey CE, Venker-Van Haagen AJ. Surgical management of pharyngeal and laryngeal airway obstruction in the dog. Vet Clin North Am Small Anim Pract 1975;5:515535.

    • Search Google Scholar
    • Export Citation
  • 28.

    Harvey CE. Review of results of airway obstruction surgery in the dog. J Small Anim Pract 1983;24:555559.

  • Figure 1—

    Endoscopic image of the left cranial ventral subsegmental bronchus (black arrow) and left cranial dorsal subsegmental bronchus (white arrow) of a dog; the left cranial ventral subsegmental bronchus has a grade 1 collapse, while the left cranial dorsal subsegmental bronchus has a grade 3 collapse.

  • Figure 2—

    Endoscopic image of the left main bronchus of a dog. The left main bronchus has a grade 3 collapse with almost complete bronchial closure in a flat, horizontal plane.

  • 1.

    Hendricks JC. Brachycephalic airway syndrome. Vet Clin North Am Small Anim Pract 1992;22:11451152.

  • 2.

    Pink JJ, Doyle RS, Hughes JML, et al. Laryngeal collapse in seven brachycephalic puppies. J Small Anim Pract 2006;47:131135.

  • 3.

    Riecks TW, Birchard SJ, Stephens JA. Surgical correction of brachycephalic syndrome in dogs: 62 cases (1991–2004). J Am Vet Med Assoc 2007;230:13241328.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 4.

    Torrez CV, Hunt GB. Results of surgical correction of abnormalities associated with brachycephalic airway obstruction syndrome in dogs in Australia. J Small Anim Pract 2006;47:150154.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 5.

    Poncet CM, Dupre GP, Freiche VG, et al. Prevalence of gastrointestinal tract lesions in 73 brachycephalic dogs with upper respiratory syndrome. J Small Anim Pract 2005;46:273279.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 6.

    Hedlund CS. Brachycephalic syndrome. In: Bojrab MJ, ed. Current techniques in small animal surgery. 4th ed. Baltimore: The Williams & Wilkins Co, 1998;357362.

    • Search Google Scholar
    • Export Citation
  • 7.

    Finder JD. Primary bronchomalacia in infants and children. J Pediatr 1997;130:5966.

  • 8.

    Fujita M, Miura H, Yashuda D, et al. Tracheal narrowing secondary to airway obstruction in two cats. J Small Anim Pract 2004;45:2931.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 9.

    McFawn PK, Mitchell HW. Effect of transmural pressure on preloads and collapse of immature bronchi. Eur Respir J 1997;10:322329.

  • 10.

    Leonard HC. Collapse of the larynx and adjacent structures in the dog. J Am Vet Med Assoc 1960;137:360363.

  • 11.

    Amis TC, McKiernan BC. Systematic identification of endobronchial anatomy during bronchoscopy in the dog. Am J Vet Res 1986;47:26492657.

    • Search Google Scholar
    • Export Citation
  • 12.

    Tagner CH, Hobson HP. A retrospective study of 20 surgically managed cases of collapsed trachea. Vet Surg 1982;11:146149.

  • 13.

    Johnson L. Small animal bronchoscopy. Vet Clin North Am Small Anim Pract 2001;31:691705.

  • 14.

    Amis TC, Kurpershoek C. Tidal breathing flow-volume loop analysis for clinical assessment of airway obstruction in conscious dogs. Am J Vet Res 1986;47:10021006.

    • Search Google Scholar
    • Export Citation
  • 15.

    Macklem PT, Mead J. Factors determining maximal expiratory flow in dogs. J Appl Physiol 1968;25:159169.

  • 16.

    Wilson TA, Hyatt RE. Forced expiration. In: Cristal RG, West JB, eds. The lungs: scientific foundations. New York: Raven Press, 1991;1021.

    • Search Google Scholar
    • Export Citation
  • 17.

    Robinson NE. Airway physiology. Vet Clin North Am Small Anim Pract 1992;22:10521057.

  • 18.

    Sotomayor JL, Godinez RI, Borden S, et al. Large-airway collapse due to acquired tracheobronchomalacia in infancy. Am J Dis Child 1986;140:367371.

    • Search Google Scholar
    • Export Citation
  • 19.

    Martinez FD. Sudden infant death syndrome and small airway occlusion: facts and a hypothesis. Pediatrics 1991;87:190198.

  • 20.

    Boogaard R, Huijsmans SH, Pijnenburg MW, et al. Tracheomalacia and bronchomalacia in children: incidence and patient characteristics. Chest 2005;128:33913397.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 21.

    Murphy KA, Brisson BA. Evaluation of lung lobe torsion in Pugs: 7 cases (1991–2004). J Am Vet Med Assoc 2006;228:8690.

  • 22.

    Rooney MB, Lanz O, Monnet E. Spontaneous lung lobe torsion in two Pugs. J Am Anim Hosp Assoc 2001;37:128130.

  • 23.

    Spranklin DB, Gulikers KP, Lanz OI. Recurrence of spontaneous lung lobe torsion in a Pug. J Am Anim Hosp Assoc 2003;39:446451.

  • 24.

    Moon F, Fossum TW. Lung lobe torsion. In: Bonagura JD, ed. Kirk's current veterinary therapy XII: small animal practice. Philadelphia: WB Saunders Co, 1995;919921.

    • Search Google Scholar
    • Export Citation
  • 25.

    Aldrich J. Atelectasis. In: King LG, ed. Textbook of respiratory disease in dogs and cats. St Louis: Elsevier, 2004;465472.

  • 26.

    Lorinson D, Bright RM, White RAS. Brachycephalic airway obstruction syndrome—a review of 118 cases. Canine Pract 1997;22(5–6):1821.

    • Search Google Scholar
    • Export Citation
  • 27.

    Harvey CE, Venker-Van Haagen AJ. Surgical management of pharyngeal and laryngeal airway obstruction in the dog. Vet Clin North Am Small Anim Pract 1975;5:515535.

    • Search Google Scholar
    • Export Citation
  • 28.

    Harvey CE. Review of results of airway obstruction surgery in the dog. J Small Anim Pract 1983;24:555559.

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