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No Correlation Between Chronic Cough and Radiographic Signs of Bronchial Narrowing in Dogs with Cardiomegaly and Left Atrial Dilation Secondary to Primary Mitral Valve Regurgitation
by
, , and
Kira Y. van Opstal
1, 
Mark D. Kittleson
2,
Erik Teske
1
,
Edoardo Auriemma
3,
Henk van den Broek
1,
Giliola Spattini
4,
Federico R. Vilaplana Grosso
5 and
Viktor Szatmári
1,*
1
Department of Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CM Utrecht, The Netherlands
2
Veterinary Information Network and School of Veterinary Medicine and Epidemiology, University of California, Davis, CA 95616, USA
3
AniCura Istituto Veterinario Novara, 28060 Granozzo con Monticello, NO, Italy
4
Clinica Veterinaria Castellarano, 42014 Castellarano, RE, Italy
5
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32611, USA
*
Author to whom correspondence should be addressed.
Animals 2025, 15(17), 2510; https://doi.org/10.3390/ani15172510
Submission received: 16 July 2025
/
Revised: 16 August 2025
/
Accepted: 22 August 2025
/
Published: 26 August 2025
(This article belongs to the Special Issue Respiratory Diseases of Companion Animals)
Simple Summary
Mitral valve regurgitation (MR) is the most common heart disease in dogs, particularly affecting middle-aged to elderly toy and small breeds. Severe MR leads to enlargement of the heart, especially the left atrium, which on radiographs often appears to compress the adjacent airways. Chronic cough, frequently due to chronic bronchitis and/or airway collapse, is also common in these dogs. The cause of coughing in dogs with a severely enlarged left atrium remains debated. Some experts attribute the cough to mechanical compression of the airways by the enlarged heart, while others believe that healthy airways cannot be compressed and that the cough is due to concurrent airway disease, with airway collapse secondary to mural weakness. Our study aimed to investigate the correlation between chronic cough, severe left atrial enlargement, and airway narrowing. Four independent veterinary radiology specialists evaluated 51 sets of radiographs for evidence of bronchial narrowing from coughing and non-coughing dogs, all with left atrial enlargement. None of the radiologists could reliably predict which dogs had a chronic cough, and agreement on bronchial narrowing was poor. Dogs with left atrial enlargement and radiographically evident airway narrowing sometimes coughed and sometimes did not. Similarly, some dogs with left atrial enlargement but no apparent airway narrowing coughed, and some did not. It was impossible to distinguish the groups based on these radiographic features. We conclude that bronchial compression by an enlarged heart is an unlikely cause of chronic cough in dogs with left atrial enlargement.
Abstract
Background: Some dogs with severe mitral valve regurgitation can have chronic cough, but its cause is unclear. Many of these dogs exhibit left principal (synonym mainstem) bronchial collapse or compression. Some clinicians believe that an enlarged heart, particularly the dilated left atrium, compresses the left principal bronchus, while others argue that a healthy bronchus cannot be compressed and that the cough is due to concurrent airway disease, such as bronchomalacia. In this study, we aimed to investigate the correlation between chronic cough and radiographic signs of bronchial narrowing in dogs with cardiomegaly secondary to primary mitral valve regurgitation. Methods: Four radiologists independently evaluated 51 sets of thoracic radiographs from client-owned dogs with cardiomegaly due to severe mitral valve regurgitation, including 26 sets of radiographs belonging to dogs with chronic (>8 weeks) cough and 25 without cough. The presence or absence of bronchial narrowing was assessed while the radiologists were blinded to patient characteristics and each other’s findings. Results: Interobserver variability was high, and the radiologists could not reliably predict which dogs had a chronic cough. Dogs with left atrial enlargement and airway narrowing sometimes coughed and sometimes did not. Likewise, some dogs with left atrial enlargement but no signs of airway compression or collapse coughed, and some did not. It was impossible to distinguish the groups based on these features. Conclusion: Bronchial compression by an enlarged heart and left atrium is an unlikely cause of chronic cough in dogs with severe primary mitral valve regurgitation.
