Bronchial stent placement in a dog with bronchomalacia and left atrial enlargement

Bronchial collapse and bronchial stenting in 9 dogs

BACKGROUND

Principal and lobar bronchial collapse is increasingly recognized as an isolated entity.

OBJECTIVE

Retrospectively describe the procedure and outcomes of dogs undergoing bronchial stenting at a single referral hospital.

ANIMALS

Nine client-owned dogs with variable degrees of collapse of the left principal bronchus (LPB), lobar bronchus 1 (LB1), and lobar bronchus 2 (LB2), and with clinically relevant signs of respiratory dysfunction.

METHODS

Data were collected from patient records. All dogs underwent stenting of the LPB and LB2. Anatomic and functional impairment grades were assigned to each case before and 4 weeks after stenting. Data regarding response to stenting and complications were evaluated.

RESULTS

Bronchial stenting was considered successful in all cases, with all dogs experiencing improved quality of life (QOL), and decreased functional impairment grade at 4 weeks post-stenting. Follow-up of >6 months was available for 6 dogs and of these, 5 were alive at 12 months, 3 were alive at 18 months, and 1 was alive at 24 months. Stent-related complications occurred in 4 dogs, and were resolvable in 3. Two dogs developed pneumothorax, 1 developed recurrent pneumonia, and 1 developed new-onset coughing. All dogs had mild and manageable coughing post-stenting.

CONCLUSIONS AND CLINICAL IMPORTANCE

Stenting of the LBP and LB2 might be an effective option for dogs with advanced collapse of these bronchi and associated signs. Although all included dogs had resolution or improvement of clinical signs considered life-threatening or as affecting QOL, ongoing coughing is expected. Patient selection appears important with regard to achieving successful outcomes.

Computed tomographic assessment of principal bronchial anatomy in dogs of various thoracic conformations: 93 cases (2012-2017)

OBJECTIVE

To better understand spatial relationships between principal bronchi and other intrathoracic structures by use of CT images of dogs of various somatotypes.

ANIMALS

93 dogs that underwent thoracic CT.

PROCEDURES

Information was collected from medical records regarding signalment and physical examination and echocardiographic findings. Two investigators recorded multiple measurements on a thoracic axial CT image from each dog.

RESULTS

Thoracic height-to-width ratio (H:W) was associated with left principal bronchus (LPB) and right principal bronchus (RPB) H:W, aortic-LPB separation, focal LPB narrowing, and aortic-vertebral overlap. Thoracic H:W was not associated with dog age, weight, sex, or brachycephalic breed. Twenty-five (27%) dogs had focal LPB narrowing, compared with 5 (5%) dogs with focal RPB narrowing (P < 0.001). Ten of 25 dogs had overlap or contact between vertebrae, aorta, LPB, and heart, suggesting a cumulative compressive effect on the LPB, while 15 had LPB-aorta contact and lack of contact between the aorta and thoracic vertebrae, suggesting an aortic constrictive effect on the LPB. None had LPB narrowing without contact from surrounding structures. Inter-rater agreement was high.

CLINICAL RELEVANCE

In dogs that underwent CT and were not selected for clinical suspicion of bronchial disease, principal bronchial morphology was associated with thoracic conformation. Focal LPB narrowing occurred more often than RPB narrowing. Focal LPB narrowing occurred with evidence of extraluminal compression, with or without contact between aorta and vertebrae. Brachycephalic breed could not be used for predicting thoracic H:W.

Bronchial Stent Placement for Palliative Treatment of Pulmonary Carcinoma with Bronchial Obstruction in a Cat

A feral, domestic shorthair was evaluated for palliative treatment of a pulmonary mass with secondary pneumonia. Because of the patient's temperament and extent of the mass, tracheobronchoscopy, bronchial stenting, and biopsy were elected, followed by adjuvant radiation therapy. Stent placement across the malignantly obstructed bronchus permitted drainage and recruitment of the infected lung lobe. Uncomplicated radiation therapy, stent extension, and debulking due to tissue ingrowth were subsequently performed. Successful palliation was achieved for 323 days with subsequent progressive pulmonary and liver metastases.

Clinicopathologic features, comorbid diseases, and prevalence of pulmonary hypertension in dogs with bronchomalacia

Background

Reports of clinicopathologic features of bronchomalacia (BM) differ because of inconsistent definitions and frequent prevalence of comorbid cardiopulmonary disease. Pulmonary hypertension (PH) secondary to BM is poorly described.

Objectives

Dogs with BM will be older but of any somatotype, and increased expiratory effort, ≥1 comorbid disease, and PH will be more common than in dogs without BM.

Animals

Client‐owned dogs (n = 210) evaluated for respiratory signs.

Methods

Medical records of dogs with paired inspiratory: expiratory‐breath‐hold computed tomography, tracheobronchoscopy, or both between January 2016 and December 2019 were retrospectively reviewed. Comparisons between dogs with and without BM using Mann‐Whitney rank sum or χ² tests (P < .05 significant were made). Because of high numbers of variables, criteria with high prevalence (>25%) were identified (n = 10) for univariate analysis (P < .005 significant). Significant variables were submitted for multivariate analysis.

Results

Bronchomalacia was identified in 41% of dogs of all sizes/somatotypes; 38% were >10 kg. All dogs with BM had ≥1 comorbid cardiopulmonary disorder. Dogs with BM were significantly older (P < .001), smaller (P < .001), and were more likely diagnosed with tracheal or mainstem bronchial collapse (P < .001) or bronchiectasis (P < .001). Multivariate analysis confirmed associations with age, tracheal or mainstem bronchial collapse, and bronchiectasis. In dogs with BM, PH was more prevalent.

Conclusions and Clinical Importance

Although significantly more common in older, smaller dogs, BM occurs in dogs of all sizes and in all instances with comorbidities. Echocardiography should be considered in dogs with BM to identify PH.

Lower airway collapse: Revisiting the definition and clinicopathologic features of canine bronchomalacia

Bronchomalacia (BM) is an inconsistently defined term in dogs, impairing understanding of clinical presentation, therapeutic response and prognosis. Herein the authors propose to clarify the definition of canine bronchomalacia (CBM) as regional to diffuse dynamic airway collapse of segmental and/or subsegmental bronchi with associated clinical signs due to airflow limitation. In contrast to tracheal collapse, mainstem bronchial collapse, and in some cases lobar collapse, CBM requires advanced imaging. Common co-morbid conditions (e.g., chronic bronchitis, mitral valve degenerative disease, etc.) should be identified during a comprehensive diagnostic evaluation. Current empiric treatments advocated in absence of clinical trials documenting efficacy in the dog warrant evaluation, as some (e.g., bronchodilators) may have detrimental effects in certain types of airway collapse in humans. There is no direct treatment for CBM, as defined above, but non-specific therapies and targeted treatment of co-morbid disease may improve clinical signs and quality of life. In this manuscript, the authors provide a review of the different types of airway collapse focusing on CBM, reviewing their definition and etiology, proposing a classification scheme, and discussing clinical signs, diagnostic testing, and treatment. Future studies should focus on both improving understanding of the etiology and natural disease progression of CBM and treatment trials.

Evaluation of bronchial narrowing in coughing dogs with heart murmurs using computed tomography

Background

The origin of cough in dogs with heart murmurs is controversial, because the cough could be primary cardiac (eg, pulmonary edema, bronchi compression by left‐sided cardiomegaly) or respiratory (eg, bronchomalacia, other bronchial or bronchiolar disease, interstitial lung disease) in origin.

Hypothesis/Objectives

To study the association between left atrium (LA) dilatation and cardiomegaly and bronchial narrowing in coughing dogs with heart murmurs using computed tomography (CT).

Animals

Twenty‐one client‐owned coughing dogs with heart murmurs and 14 historical control dogs.

Methods

Dogs with cough and murmur were prospectively recruited over 4 months. Cervical and thoracic radiography, echocardiography, and thoracic CT were performed in enrolled dogs. Control dogs, with no disease on thoracic CT and no records of heart murmur and coughing, were gathered from the institution's computerized database. Degree of bronchial narrowing was assessed using the bronchial‐to‐aorta (Ao) ratio, measured by 3 radiologists blinded to the clinical findings. After identifying bronchi that were significantly narrowed in dogs with murmur compared to controls, the relationship between degree of narrowing and LA/Ao ratio (measured echocardiographically) and vertebral heart scale (VHS) measured radiographically was studied in dogs with murmur using mixed‐effects regression.

Result

Significant narrowing was identified for all left‐sided bronchi and the right principal, middle, and caudal bronchi in the coughing dogs, compared with controls. Increasing LA size and VHS were significantly inversely associated with diameter for all left‐sided and right‐sided bronchi indicated above.

Conclusion and Clinical Importance

Results indicate an association between LA enlargement and cardiomegaly and bronchial narrowing and support heart size‐associated exacerbation of cough in dogs with murmurs.

Bilateral bronchial stent deployment for palliative treatment of a compressive intrathoracic mass in a cat

Case summary

Bronchial stents may be useful to relieve clinical signs of extraluminal compression. Herein we describe a case which, to our knowledge, is the first cat where bilateral bronchial stents have been used clinically. Respiratory signs of principal bronchial compression were alleviated after the stent procedure. Minor complications occurred, specifically: severe hypoxia during stent deployment; a transient, self-limiting postoperative pneumothorax possibly associated with ventilation-induced lung injury; bronchopneumonia (possibly pre-existing); and transient worsening of cough postoperatively. Stents were well- tolerated long- term. The cat was euthanased at 44 weeks post-stent procedure, owing to clinical signs of regurgitation, seemingly related to oesophageal dysfunction associated with tumour invasion.

Relevance and novel information

In this case, it appeared that bronchial stents were feasible and the procedure was associated with long-term improvement in respiratory signs related to extraluminal bronchial compression.