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Heart Murmurs in Dogs

Heart Murmurs in Dogs: Causes, Symptoms, and Management

A heart murmur in dogs is an abnormal sound heard during the heartbeat cycle caused by turbulent blood flow within the heart or connected large vessels, disrupting regular blood flow. Heart murmurs are described based on timing, location, intensity, quality, and pitch.Β 

The causes of heart murmurs in dogs include congenital heart defects, valvular disease, heartworm disease, cardiomyopathy, endocarditis, or anemia.Β 

The symptoms of a heart murmur in dogs vary depending on its severity and the underlying cause. Common symptoms include coughing, difficulty breathing, lethargy, fainting or collapse, reduced appetite, and swollen abdomen. Heart murmur in older dogs are more common due to degenerative changes in the heart valves.Β 

Managing heart murmurs in dogs involves regular monitoring, medication, diet and exercise, and possible surgical intervention.

What are Heart Murmurs in Dogs?

Heart murmurs in dogs are abnormal sounds produced during the cardiac cycle due to turbulent blood flow, detected by veterinarians using a stethoscope. β€œHeart murmurs in dogs are abnormal sounds heard by a veterinarian when listening to the heart, and can be an indication of heart disease,” according to the study byΒ  Feroli, K., & Failla, M. titled β€œHeart murmur,” 1993.

The effects of heart murmurs in dogs include exercise intolerance, coughing, breathing difficulties, lethargy, weakness, fainting or collapsing, weight loss, and decreased appetite.

What part of a Dog's Heart is prone to Heart Murmurs?

The parts of a dog's heart prone to heart murmurs are the heart valves, leading to disruptions in blood flow and causing distinct murmuring sounds during cardiac cycles. β€œThe heart valves, specifically the quadricuspid aortic valve, can be prone to heart murmurs in dogs,” according to the study by Kettner, F., CΓ΄tΓ©, E., & Kirberger, R. titled β€œQuadricuspid aortic valve and associated abnormalities in a dog,” 2005.

Heart valves maintain proper blood flow within the heart anatomy in dogs. Abnormalities in the valves, such as stenosis (narrowing) or regurgitation (leakage), compromise normal blood flow, leading to turbulence and audible murmurs. The murmurs occur during different phases of the cardiac cycle, indicating the severity and location of the underlying valve issue.Β 

What is the cause of a heart murmur?

The causes of heart murmurs in dogs are listed below.

  • Patent Ductus Arteriosus (PDA): An abnormal blood vessel that remains open after post-birth.
  • Aortic or Pulmonic Stenosis: Narrowing of the aorta or pulmonary artery that restricts blood flow.
  • Ventricular Septal Defect (VSD): An opening in the septum separating the heart's ventricles.
  • Atrial Septal Defect (ASD): An opening in the septum between the heart's atria.
  • Mitral Valve Disease: Degeneration or dysfunction of the mitral valve, leading to regurgitation of blood.
  • Dilated Cardiomyopathy (DCM): Enlargement of the heart chambers, reducing the heart's efficiency.
  • Endocarditis: Infection and inflammation of the inner lining of the heart and its valves.
  • Heartworm Disease: A condition caused by parasitic worms (Dirofilaria immitis) living in the heart and pulmonary arteries.
  • Hypertrophic Cardiomyopathy (HCM): Thickening of the heart muscle, often in the left ventricle, leading to reduced chamber size and impaired filling.
  • Anemia: Reduced red blood cell count causes increased blood flow velocity, leading to a murmur.
  • Hyperthyroidism: An overactive thyroid gland increases heart rate and causes murmurs.
  • Innocent or Physiologic Murmurs: Harmless murmurs are often found in puppies that disappear over time.

Can a heart murmur be an early indicator of heart disease in dogs?

Yes, a heart murmur can be an early indicator of heart disease in dogs. β€œSoft murmurs in small-breed dogs are strongly indicative of subclinical heart disease, while throbbing murmurs are associated with more severe disease,” according to the study by Ljungvall, I., Rishniw, M., Porciello, F., Ferasin, L., & Ohad, D. titled β€œMurmur intensity in small-breed dogs with myxomatous mitral valve disease reflects disease severity,” 2014.Β 

Dogs exhibiting a heart murmur during a routine check-up require close attention. Not all heart murmurs indicate heart disease in dogs, but they must never be ignored.

How does age affect the likelihood of a dog developing a heart murmur?

Age affects the likelihood of a dog developing a heart murmur, with older dogs at a higher risk due to changes in cardiac function and the manifestation of hereditary diseases. β€œHypertrophic cardiomyopathy in an aged dog shows morphological hallmarks of the condition, which can lead to cardiac murmur and convulsive seizure,” according to the study by Washizu, M., Takemura, N., Machida, N., Nawa, H., Yamamoto, T., Mitake, H., & Washizu, T. titled β€œHypertrophic cardiomyopathy in an aged dog,” 2003.

Dogs’ heart muscles weaken as they age, making them prone to valve degeneration. The degeneration accelerates in breeds genetically predisposed to cardiac conditions. The heart struggles to maintain proper blood flow as it ages, increasing the likelihood of turbulent blood flow audible as a murmur.

Is there a genetic component to heart murmurs in dogs?

Yes, there is a genetic component to heart murmurs in dogs, particularly in breeds prone to congenital heart defects due to hereditary factors. β€œRecent years have seen a rise in new breed predispositions for canine heart disease, highlighting the need for veterinarians to recognize these changes and counsel breeders accordingly,” according to the study by Buchanan, J. titled β€œChanging Breed Predispositions in Canine Heart Disease,” 1993.

Genetic testing identifies genetic predisposition early on, allowing for proactive measures to prevent or mitigate the progression of heart conditions.Β 

What are the Symptoms of Heart Murmurs in Dogs?

The symptoms of heart murmurs in dogs are listed below.

  • Coughing: Persistent coughing, especially at night or after exercise, is a sign of heart problems.
  • Difficulty Breathing: Labored or rapid breathing, shortness of breath, and excessive panting indicate heart issues.
  • Exercise Intolerance: Dogs with heart murmurs tire easily, show reluctance to exercise, or exhibit decreased stamina.
  • Weakness or Fainting: Some dogs experience weakness, collapse, or fainting spells (syncope), especially during exertion.
  • Distended Abdomen: Swelling in the abdomen due to fluid accumulation (ascites) is associated with heart disease.
  • Poor Appetite: Reduced interest in food and subsequent weight loss are heart murmur signs.
  • Bluish Gums or Tongue: Cyanosis, or a bluish tint to the gums or tongue, indicates poor oxygenation due to heart issues.
  • Restlessness: Dogs have difficulty settling down, especially at night.
  • Swelling: Fluid retention caused by heart inefficiencies leads to swelling in the legs (edema).

What complications can arise from a heart murmur in dogs?

The complications that arise from a heart murmur in dogs are listed below.

  • Congestive Heart Failure (CHF): Underlying conditions causing heart murmurs, such as mitral valve disease or dilated cardiomyopathy, lead to congestive heart failure. The heart's inability to pump blood efficiently results in fluid accumulation in the lungs (pulmonary edema), abdomen (ascites), or other body tissues.
  • Pulmonary Hypertension: Elevated blood pressure in the pulmonary arteries creates conditions like heartworm or left-sided heart disease, increasing stress on the heart.
  • Cardiac Arrhythmias: Irregular heart rhythms develop as a complication of heart disease, leading to sudden weakness, collapse, or even sudden death.
  • Exercise Intolerance: Dogs with significant heart murmurs tire quickly, become lethargic, or show reluctance to exercise due to reduced cardiac output.
  • Syncope (Fainting): Reduced blood flow to the brain due to severe heart disease causes episodes of fainting or collapse, especially during physical exertion or excitement.
  • Thromboembolism: Blood clots form due to abnormal blood flow patterns and travel to and block important blood vessels, leading to life-threatening conditions like stroke.
  • Endocarditis: Infection of the heart valves occurs, particularly in dogs with pre-existing valve abnormalities leading to severe illness and heart dysfunction.
  • Poor Growth and Development: Puppies with heart defects suffer from congenital heart defects, poor growth, weight gain, and developmental delays.
  • Renal (Kidney) Complications: Chronic heart conditions lead to reduced kidney perfusion, causing kidney dysfunction or failure over time.
  • Ascites and Edema: Fluid accumulation in the abdomen (ascites) and tissues (edema) occur due to right-sided heart failure, leading to discomfort and difficulty breathing.

How are Heart Murmurs in Dogs Diagnosed?

Heart murmurs in dogs are diagnosed by a veterinarian through echocardiograms to assess cardiac structure and function.Β 

Veterinarian diagnosis procedures for heart murmurs include auscultation, echocardiography, chest X-rays, electrocardiography, blood pressure measurement, blood tests, cardiac biomarkers, Doppler ultrasound, Holter monitoring, and, in rare cases, cardiac catheterization.Β 

Heart murmurs are asymptomatic in the early stages, so regular check-ups are essential to detect abnormalities promptly.

Can a heart murmur be detected in puppies?

Yes, heart murmurs can be detected in puppies through physical examinations and monitoring. Regular check-ups enable veterinarians to listen for abnormal heart sounds indicating a heart murmur.Β 

The murmurs vary in intensity and must be monitored to detect associated risks or developmental concerns. Veterinarians recommend appropriate treatment plans and lifestyle adjustments to manage the condition.Β 

Early intervention prevents complications and improves the overall quality of life for puppies.

How long can Dogs live with Heart Murmurs?

Dogs with heart murmurs live for an average of two years, depending on the severity of the condition. Regular monitoring and appropriate treatments influence the prognosis and overall quality of life for affected dogs. β€œThe median survival time for all-cause mortality in dogs with heart murmurs was 25.4 months after disease detection,” according to the study by Mattin, M., Boswood, A., Church, D., McGreevy, P., O'Neill, D., Thomson, P., & Brodbelt, D. titled β€œDegenerative mitral valve disease: Survival of dogs attending primary-care practice in England,” 2015.

Early detection and intervention of the signs of heart murmur in dogs through medications or lifestyle changes significantly impact the dog's lifespan and well-being. Ensuring compliance with prescribed medications and regular check-ups enhances the chances of controlling symptoms.

Can Dogs Die with Heart Murmurs?

Yes, dogs die with heart murmurs. Dogs with untreated or advanced heart murmurs face an increased risk of mortality if the condition progresses to heart failure. β€œA dog died despite medical treatment for cardiac murmurs in a five-year-old boxer dog, indicating that heart murmurs can lead to death in dogs,” according to the study by Jacobs, G., Calvert, C., Hall, D., & Kraus, M. titled β€œDiagnosis of right coronary artery to right atrial fistula in a dog using two-dimensional echocardiography,” 1996.

Untreated heart murmurs impede the heart's ability to pump blood throughout the body effectively. A cascade of detrimental effects, including fluid buildup in the lungs, decreased energy levels, and potential organ damage, are the result.Β 

What Dog Breeds Are Prone to Heart Murmurs?

Dog breeds prone to heart murmurs include Cavalier King Charles Spaniels, Boxers, and Chihuahuas. Certain breeds exhibit a higher prevalence of heart valve abnormalities and cardiac issues that lead to the development of murmurs.

Cavalier King Charles Spaniels have a high incidence of mitral valve disease, which results in heart murmurs. β€œCavalier King Charles Spaniels (CKCS) have a high prevalence of chronic mitral valve disease, leading to heart murmurs in 22% of the studied dogs,” according to the study by Aw, B., & Buchanan, J. titled β€œChronic mitral valve disease in cavalier King Charles spaniels: 95 cases (1987-1991),” 1993.

Boxers are prone to aortic stenosis, which causes turbulent blood flow, leading to murmurs. β€œBoxers are predisposed to subaortic and pulmonic stenosis, with a prevalence of 26.5% for heart murmurs in the studied dogs,” according to the study by HΓΆpfner, R., Glaus, T., Gardelle, O., Amberger, C., Glardon, O., Doherr, M., & Lombard, C. titled β€œ[Prevalence of heart murmurs, aortic and pulmonic stenosis in boxers presented for pre-breeding exams in Switzerland],” 2010.

Chihuahuas are susceptible to myxomatous mitral valve disease (MMVD), which causes Chihuahua heart murmur. β€œIntestinal mucosal injury risk is significantly higher in Chihuahuas with heart failure due to myxomatous mitral valve disease, suggesting the risk could increase with worsening heart disease,” according to the study by Araki, R., Iwanaga, K., Ueda, K., & Isaka, M. titled β€œIntestinal Complication With Myxomatous Mitral Valve Diseases in Chihuahuas,” 2021.Β 

What are the Treatments for Heart Murmurs in Dogs?

The treatments for heart murmurs in dogs are listed below.

  • Diuretics: Diuretics reduce fluid buildup in the lungs and abdomen.
  • ACE Inhibitors: Inhibitors like enalapril and benazepril lower blood pressure and reduce the heart's workload.
  • Beta-blockers: Beta-blockers like atenolol control heart rate and reduce arrhythmias.
  • Positive Inotropes: Intropes strengthen heart contractions and include pimobendan.
  • Antiarrhythmics: Products such as sotalol that manage abnormal heart rhythms.
  • Low-sodium Diet: A nutritious low-salt diet helps reduce fluid retention and manage heart failure symptoms.
  • Weight Management: Maintaining an optimal weight reduces the heart's workload.
  • Exercise Modification: Tailoring exercise routines to the dog's condition and avoiding strenuous activities improve cardiovascular health.
  • Valve Repair or Replacement: A surgical procedure for severe valvular disease.
  • PDA Ligation: Surgical closure of a patent ductus arteriosus.
  • Balloon Valvuloplasty: A non-surgical procedure to open narrowed heart valves.
  • Heartworm Treatment: A treatment to remove heartworms causing murmurs.
  • Antibiotics: Antibiotics treat bacterial infections causing endocarditis.
  • Oxygen Therapy: Oxygen therapy is necessary for dogs with breathing difficulties.
  • Fluid Therapy: Fluid therapy manages a dog’s dehydration and maintains fluid balance.
  • Supplements: Omega-3 fatty acids, taurine, and CoQ10 support heart health.
  • Herbal Remedies: A supplement to relieve heart murmurs used under veterinary guidance.

How can CBD Products help treat Heart Murmurs in Dogs?

CBD products help treat heart murmurs in dogs by improving heart efficiency and regulating cardiac output. β€œActivation of CB2 receptors exhibits cardioprotective properties, helping to maintain appropriate amount of ATP in cardiomyocytes,” according to the study by Polak, A., Harasim, E., & Chabowski, A. (2016). Effects of activation of endocannabinoid system on myocardial metabolism.

CBD oil products have anti-inflammatory properties that help reduce inflammation in the heart muscles, potentially alleviating the strain on the heart caused by murmurs. CBD's ability to reduce anxiety and stress in dogs contributes to overall cardiac health, as stress exacerbates heart conditions.Β 

Heart murmur-related conditions, such as arrhythmias, benefit from CBD's influence on the endocannabinoid system by maintaining proper heart rhythm and managing arrhythmic episodes.

How Much Does it Cost to Treat Heart Murmurs in Dogs?

The cost of treating heart murmurs in dogs ranges from $500 to $10,000 for initial treatment. The cost varies based on severity, geographic location, required interventions, age, overall health, and underlying genetic factors.Β 

Expenses range from diagnostic tests to ongoing management strategies. β€œThe company paid out $5,858,000 for dog heart murmur claims in 2023 alone. Averages paid out to individual pet owners for singular canine heart murmur claims fell between $200 and $500, with some outliers for more severe or milder cases,” according to Trupanion Pet Insurance claims data.Β 

Diagnosing heart murmurs involves echocardiograms and blood work, which elevates costs.

Can Dogs with Heart Murmurs be treated at home?

Yes, dogs with heart murmurs can be treated at home with regular monitoring, a healthy diet, exercise, weight management, oral medications, and regular check-ups. β€œIncidentally detected heart murmurs in dogs can be managed using murmur characteristics, signalment profiling, and multifactorial decision-making to choose an optimal course of treatment,” according to the study by CΓ΄tΓ©, E., Edwards, N., Ettinger, S., Fuentes, V., Macdonald, K., Scansen, B., Sisson, D., & Abbott, J. titled β€œManagement of incidentally detected heart murmurs in dogs and cats,” 2015.

Monitor the dog's behavior, energy levels, appetite, and breathing. Provide a balanced, heart-healthy diet and maintain a moderate exercise routine. Ensure the dog stays at a healthy weight, administer oral medications as prescribed, and schedule regular veterinary check-ups to monitor the dog's heart condition and adjust medications as needed.

What to avoid if your dog has a heart murmur?

The conditions to avoid if your dog has a heart murmur are listed below.

  • Strenuous Exercise: Avoid activities that place excessive strain on the dog's heart, such as intense running, jumping, or prolonged vigorous play. Opt for gentle walks and low-impact exercises instead.
  • Excessive Heat: Avoid exposing dogs to high temperatures, especially during hot weather. Heat adds stress on the heart, so keep dogs cool and well-hydrated.
  • Stressful Situations: Minimize stressors in the dog's environment, as stress worsens heart conditions. Stressors include loud noises, crowded areas, and situations that cause anxiety or excitement.
  • Secondhand Smoke: Avoid exposing dogs to cigarette smoke or other forms of secondhand smoke, as it contributes to heart and respiratory problems.
  • Obesity: Maintain a healthy weight for the dog through a low-sodium diet and regular exercise. Obesity puts extra strain on the heart and worsens heart murmurs.
  • Certain Medications and Supplements: Consult a veterinarian before giving dogs new medications or supplements, as some worsen heart conditions.
  • Skipping Veterinary Check-Ups: Regular veterinary check-ups monitor the dog's heart condition and adjust treatment as needed. Don't skip appointments or delay seeking veterinary care if any concerning symptoms are noticed.

Is it possible to prevent Heart Murmurs in Dogs?

Yes, it is possible to prevent heart murmurs in dogs by screen breeding and early detection through regular veterinary check-ups. β€œEarly detection of heart murmurs in puppies allows breeders to avoid breeding from dogs with genetic defects and prevent the continuation of genetic defects in breeding lines,” according to the study by Pugliese, M., Biondi, V., Maestra, R., & Passantino, A. titled β€œIdentification and Clinical Significance of Heart Murmurs in Puppies Involved in Puppy Trade,” 2021.Β 

Screen breeding dogs for genetic predispositions to heart conditions and exclude candidates from breeding programs. Early detection through regular veterinary check-ups identifies initial signs of heart murmurs or abnormalities. Prompt intervention and management prevent the progression of mild murmurs into more severe cardiac issues.

What is the Prognosis of Heart Murmurs in Dogs

The prognosis of heart murmurs in dogs hinges on factors like the underlying cause, severity of the condition, and response to treatment. β€œMost dogs with left apical systolic heart murmurs do not develop congestive heart failure, and the prevalence of mitral valvular disease is higher in Cavalier King Charles spaniels than in the 6 small breeds investigated,” according to the study by Serfass, P., Chetboul, V., Sampedrano, C., Nicolle, A., Benalloul, T., Laforge, H., Gau, C., HΓ©bert, C., Pouchelon, J., & Tissier, R. titled β€œRetrospective study of 942 small-sized dogs: Prevalence of left apical systolic heart murmur and left-sided heart failure, critical effects of breed and sex,” 2006.

Cardiac function and heart efficiency are key determinants affecting dogs’ prognosis of heart murmurs. Dogs with compromised cardiac function have a poorer prognosis than dogs with maintained heart efficiency.