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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. [ABSTRACT FROM AUTHOR]

Background: Stenting has become popular to treat tracheal collapse in dogs, but complications might arise and negatively affect treatment outcome. Objectives: Determine the overall prevalence of complications of tracheal stenting in dogs. Methods: A bibliographic search was performed of publications from 2000 to 2020. Studies were assessed for quality of evidence and measured prevalence of the 8 most commonly reported complications after tracheal stenting in dogs (stent fracture, stent migration, relapsing collapse, granuloma formation, tracheobronchial infections, and early, late, and clinically relevant late cough). Random effects meta‐analyses were used to estimate pooled complications prevalence. Results: Fifteen studies met inclusion criteria. Cough (early: 99%; 95% confidence interval [95% CI]: 95%–100%, late: 75%; 95% CI: 63%–85%, and clinically relevant: 52%; 95% CI: 42%–61%), tracheobronchial infections (24%; 95% CI: 14%–35%), and granulomas (20%; 95% CI: 11%–30%) were common after tracheal stenting. Stent fractures (12%; 95% CI: 5%–20%), relapsing collapse (10%; 95% CI: 5%–15%), and stent migration (5%; 95% CI: 1%–9%) were less frequent. Significant heterogeneity among studies was identified for the estimated prevalence of stent fracture, granulomas, infections, and late cough. Conclusions and Clinical Importance: Tracheal stenting in dogs is associated with a high risk of coughing and a moderate risk of tracheobronchial infections and granuloma formation. Because most complications will impact a dog's quality of life, owners must be informed that tracheal stenting is a second‐line procedure that does not necessarily alleviate the need for medical treatment and frequent follow‐up visits. Additional studies are warranted to identify the risk factors of these complications. [ABSTRACT FROM AUTHOR]

Looking more closely at the results, the gradient was highest for left caudal bronchus (LB2) and left principal bronchus (LPB), which are the bronchi located just dorsal to the left atrium (Figure 1). It therefore seems logical that these bronchi would be the most narrowed bronchi associated with an enlarged left atrium. [Extracted from the article]