Heartworms in Dogs: Causes, Symptoms, and Treatment

What is heart cough in dogs?

A cardiac cough is a cough caused by heart disease—typically by an enlarged heart pressing on the airways (bronchi, trachea) or by pulmonary edema resulting from heart failure (fluid buildup in the lungs). It is a warning sign of advanced heart disease.

Important: Not every cough in dogs is a heart-related cough. Differential diagnoses include bronchitis, tracheal collapse, pneumonia, and heartworms. A heart-related cough is distinguished from other causes through diagnostic testing (X-rays, echocardiography).

Background + Scientific Context

Keene et al. (2019, JVIM, PubMed 31211475) published the ACVIM consensus guidelines on myxomatous mitral valve disease (MMVD)—the most common heart disease in dogs: As MMVD progresses, it causes left atrial dilatation with consequent pressure on the left main bronchus (cough) and pulmonary edema (dyspnea, wet cough). The staging system (A–D) enables prognostic classification and treatment decisions.

Boswood et al. (2016, JVIM, PubMed 27511005) presented the EPIC study—the first large randomized controlled trial of pimobendan administration in the preclinical stage of MMVD (stage B2): Pimobendan prolonged the time to the onset of clinical heart failure by a median of 15 months. The study demonstrates that early treatment in asymptomatic dogs with cardiac enlargement improves the prognosis.

In the QUEST study, Häggström et al. (2008, JVIM, PubMed 18945316) compared pimobendan with benazepril in dogs with overt heart failure due to MMVD: pimobendan significantly prolonged survival. Combination therapy (pimobendan + furosemide + RAAS inhibitor) is now the standard of care in cardiology.

Vitomalia-Position

A persistent cough is not just an “old-age cough.” Dogs don’t cough simply because of their age. Recurring nighttime coughing in small breeds is a warning sign that should be evaluated with an echocardiogram—not treated with cough syrup.

When is heart cough a concern in dogs?

• In dogs over 7 years of age, especially small breeds (Cavalier King Charles Spaniel, Chihuahua, Dachshund): predisposition to MMVD
• For dry or wet nighttime coughs that have worsened
• If you experience a combination of coughing, rapid fatigue, and fainting spells: advanced heart disease
• If a heart murmur is detected during a veterinary examination: regular cardiac checkups
• For dogs with a history of heartworm infection: Rule out heartworm

Practical application

Distinguishing between a heart-related cough and other types of cough:

MMVD Staging (simplified): - Stage A: Predisposed breed, no findings — follow-up recommended - Stage B1: Heart murmur, no cardiac enlargement — Observation - Stage B2: Heart murmur + cardiac enlargement — Pimobendan indicated (according to EPIC) - Stage C: Clinical heart failure — combination therapy - Stage D: Refractory heart failure — intensified therapy

Common Mistakes & Myths

• “My dog only coughs at night—that’s normal.” Nighttime coughing is a classic sign of heart problems—it occurs with pulmonary edema, which worsens when the dog is lying down. It’s not a normal part of aging.
• "Treat with cough medicine until the vet appointment." Cough suppressants mask the symptom without treating the underlying cause. If you suspect a heart-related cause, see a vet immediately.
• "Heart cough is only a problem in large dogs." Small breeds are disproportionately affected by MMVD—nearly 100% of Cavalier King Charles Spaniels develop the condition as they age.

Current State of Research (2026)

MMVD is the most extensively studied heart disease in dogs. Genetic tests for MMVD predisposition are available for Cavalier King Charles Spaniels. NT-proBNP, as a biomarker, allows for non-invasive assessment of cardiac workload. Combination therapy (pimobendan + loop diuretic + ACE inhibitor + spironolactone) is the ACVIM standard of care for stages C/D.

Frequently Asked Questions

What does a heart cough sound like in dogs?

A heart-related cough often sounds wet or productive—as if the dog is trying to bring something up but can’t. It often occurs at night or after physical exertion. In contrast, a tracheal collapse cough sounds dry and cackling, while kennel cough sounds distinctly barking.

What should I do if my dog coughs at night?

Make a vet appointment—as soon as possible, don’t put it off for weeks. The vet will perform a physical exam (listen for heart murmurs), X-rays (to check heart size and lung edema), and an echocardiogram if necessary. In the meantime: limit activity, avoid excitement, and keep the environment cool.

Can heart cough in dogs be treated?

Yes—heart disease can be effectively managed with medication if detected early. Pimobendan has been shown to prolong the symptom-free period and overall survival. While a cure is not possible, modern standard of care can significantly improve both quality of life and life expectancy.

Related terms

• Heart Failure in Dogs
• Dilated cardiomyopathy in dogs
• Heartworms in Dogs
• Bronchitis in Dogs
• Coughing in Dogs

Sources & Further Reading

1. Keene, B. W., Atkins, C. E., Bonagura, J. D., Fox, P. R., Häggström, J., Fuentes, V. L., Oyama, M. A., Rush, J. E., Stepien, R., & Uechi, M. (2019). ACVIM Consensus Guidelines for Diagnosis and Treatment of Myxomatous Mitral Valve Disease in Dogs. Journal of Veterinary Internal Medicine, 33(3), 1127–1140. https://pubmed.ncbi.nlm.nih.gov/31211475/

2. Boswood, A., Häggström, J., Gordon, S. G., Wess, G., Walker, A. L., Borgarelli, M., Burkett, P., Chompoosri, S., Cunningham, S. M., et al. (2016). Effect of Pimobendan in Dogs with Preclinical Myxomatous Mitral Valve Disease and Cardiomegaly: The EPIC Study—A Randomized Clinical Trial. Journal of Veterinary Internal Medicine, 30(6), 1765–1779. https://pubmed.ncbi.nlm.nih.gov/27511005/

3. Häggström, J., Boswood, A., O'Grady, M., Jöns, O., Smith, S., Swift, S., Borgarelli, M., et al. (2008). Effect of pimobendan or benazepril hydrochloride on survival times in dogs with congestive heart failure caused by naturally occurring myxomatous mitral valve disease. Journal of Veterinary Internal Medicine, 22(5), 1124–1135. https://pubmed.ncbi.nlm.nih.gov/18945316/