Heart Murmur in Dogs

Heart murmurs in dogs are not uncommon, but they can be a source of concern for pet owners. A heart murmur is an abnormal heart sound caused by turbulent blood flow. It's crucial to understand that heart murmurs can vary greatly in their severity and implications. Some murmurs are benign and may not impact your dog's life, while others can indicate serious heart conditions. In this article, we will delve into the intricacies of heart murmurs, offering insights and guidance to ensure the best care for your furry friend.

What is a Heart Murmur in Dogs?

A heart murmur is an abnormal sound heard during a veterinarian's examination of a dog's heart using a stethoscope. It is caused by turbulent blood flow within the heart or blood vessels. Murmurs are graded on a scale from I to VI, with grade I being the softest and grade VI the loudest. The grade helps assess the severity of the murmur.

What are Heart Murmur Grades in Dogs? 

Grading system helps veterinarians classify the severity of heart murmurs based on their intensity, and it can provide important information about the underlying heart condition. 

• Grade 1: Barely audible - The least serious type of heart murmur, often difficult to detect without a stethoscope.

• Grade 2: Soft murmur, but easily heard with a stethoscope - Slightly more noticeable than a Grade 1 murmur but still relatively mild.

• Grade 3: Intermediate loudness, most serious problems will result in at least a grade 3 heart murmur in dogs - This grade indicates a moderate intensity murmur and may suggest a more significant underlying issue.

• Grade 4: Loud murmur that can be heard on either side of the chest - A Grade 4 murmur is quite noticeable and may indicate a more severe heart condition.

• Grade 5: Very loud murmur - A Grade 5 murmur is considered severe and may require immediate attention.

• Grade 6: Very loud murmur that can be felt by placing a hand on the dog's chest wall - The most severe type of heart murmur, often associated with critical heart disease and requiring immediate medical intervention.

The grade of a heart murmur can provide valuable information to the veterinarian and guide further diagnostic and treatment decisions. Dog owners need to work closely with their veterinarian if their dog is diagnosed with a heart murmur, as the underlying cause and appropriate management can vary depending on the grade and other factors.

Symptoms of Heart Murmur in Dogs

Not all dogs with heart murmurs will display symptoms, and the severity of symptoms can vary depending on the underlying cause and the grade of the murmur. Common symptoms may include:

• Fatigue and Weakness

• Coughing

• Rapid or labored breathing

• Fainting or collapsing (in severe cases)

• Decreased appetite

• Weight loss

• Gums and/or tongue are bluish in color

• Swollen abdomen (due to fluid accumulation)

What Causes Heart Murmurs in Dogs?

Heart murmurs in dogs are caused by turbulent blood flow within the heart or blood vessels. These abnormal sounds are typically heard when a veterinarian listens to a dog's chest using a stethoscope. There are various underlying causes of heart murmurs in dogs, which can be categorized into two main types: innocent (also known as functional or benign) murmurs and pathological (abnormal) murmurs.

1. Innocent (Functional or Benign) Murmurs

Innocent heart murmurs are common in puppies and young dogs and are typically not associated with underlying heart disease. They often occur due to changes in blood flow patterns as a puppy's heart develops.
These murmurs are usually low-grade (Grade 1 or 2) and tend to disappear as the dog matures.
Innocent murmurs generally don't require specific treatment and are not indicative of a serious health issue.

2. Pathological (Abnormal) Murmurs

Pathological heart murmurs are associated with underlying heart disease or other health conditions. They can occur at any age and are usually of higher grades (Grade 3 or higher).
Common causes of pathological heart murmurs in dogs include:

• Heart valve disease: Conditions like mitral valve disease and aortic valve disease can cause turbulent blood flow as the valves fail to function properly.

• Congenital heart defects: Some dogs are born with structural heart abnormalities that can lead to murmurs.

• Cardiomyopathy: This is a group of diseases that affect the heart muscle, making it less effective at pumping blood.

• Heartworm disease: Infestation with heartworms can cause obstructions in the heart's blood vessels and result in murmurs.

• High blood pressure (hypertension): Elevated blood pressure can cause turbulent flow in the blood vessels, leading to murmurs.

• Anemia: A low red blood cell count can cause increased blood flow velocity, resulting in murmurs.

How Serious is a Heart Murmur in a Dog?

The seriousness of a heart murmur in a dog depends on several factors, including the grade of the murmur, the underlying cause, the dog's age, and overall health. Such as severe heart valve disease or congenital defects may be life-threatening. What's more, early detection and treatment of heartworms are crucial. In advanced cases, heartworm disease can be life-threatening and require aggressive treatment.

Diagnosis and Treatment

If your veterinarian detects a heart murmur in your dog, they will perform further tests to determine the underlying cause and assess the severity of the condition. Diagnostic tests may include:

• Chest X-rays

• Echocardiography (ultrasound of the heart)

• Electrocardiography (ECG)

• Blood tests

• Blood pressure measurement

Treatment options will depend on the cause and severity of the heart murmur:

• Medications: Dogs with heart murmurs may be prescribed medications to manage symptoms and slow the progression of the underlying condition. Common drugs include diuretics, ACE inhibitors, and beta-blockers.

• Surgery: In cases of congenital defects or severe valve abnormalities, surgical intervention may be necessary to correct the problem.

• Diet and Lifestyle: Dietary changes, weight management, and exercise restrictions may be recommended to support your dog's heart health.

• Regular Monitoring: Dogs with heart murmurs will require ongoing veterinary care, including regular check-ups and monitoring of their condition.

How Long Can a Dog Live with a Heart Murmur?

The lifespan of a dog with a heart murmur depends on several factors, including the underlying cause of the murmur, the grade or severity of the murmur, the age and overall health of the dog, and the effectiveness of treatment and management. Here are some general guidelines:

• Dogs with innocent murmurs, which are common in puppies and young dogs, typically have a normal lifespan.

• Dogs with mild to moderate heart disease can often live for several years with appropriate treatment and management. 

• In cases of more severe heart disease or congenital defects, the prognosis may be less favorable. However, some dogs can still live for several months to a few years with proper care and treatment.

Is It OK to Walk a Dog with a Heart Murmur?

Whether or not it's okay to walk a dog with a heart murmur depends on several factors, including the severity of the murmur, the underlying cause of the murmur, and the dog's overall health. In general, mild to moderate heart murmurs may not necessarily restrict a dog from moderate exercise or short walks. However, if you notice signs of distress, such as excessive panting, weakness, coughing, or difficulty breathing during or after exercise, you should stop the activity and consult your veterinarian.

What Should I Feed My Dog with a Heart Murmur?

• Common prescription diets for heart disease include those low in sodium and high in specific nutrients like omega-3 fatty acids

• Reducing the sodium (salt) intake is often crucial for dogs with heart disease, as excess sodium can contribute to fluid retention and increased strain on the heart

• Providing your dog with high-quality protein sources can help maintain muscle mass and overall body condition. Lean meats like chicken, turkey, or fish can be included in their diet

• Frequent, smaller meals

How Can I Prevent Heart Murmurs in My Dog?

Heart murmurs in dogs are typically a symptom of an underlying condition rather than a condition that can be directly prevented. However, you can take steps to reduce the risk of certain heart conditions and promote your dog's overall heart health:

• Heartworm Prevention: Heartworm preventatives are typically administered monthly.

• Balanced Diet: Provide your dog with a well-balanced diet that meets their nutritional needs.

• Maintain a Healthy Weight: Keep your dog at a healthy weight through proper diet and regular exercise.

• Dental Care: Maintain good dental hygiene for your dog. Dental infections can lead to systemic inflammation and potentially affect the heart.

• Avoid Excessive Stress: Minimize stressful situations for your dog, as stress can have an impact on heart health. 

• Breed-Specific Considerations: Be aware that certain dog breeds are more predisposed to specific heart conditions.

• Mitral Valve Disease (MVD): Cavalier King Charles Spaniel
  Dilated Cardiomyopathy (DCM): Doberman Pinscher, Boxer.
  Aortic Stenosis: Newfoundland
  Sudden Death Syndrome: Boxer, Great Dane, and Cocker Spaniel.
  Congenital Heart Defects: Bulldogs and Boston Terriers.

Conclusion

Heart murmurs in dogs can be a sign of an underlying heart problem, and while they can be concerning, many dogs with murmurs can lead happy lives with appropriate management and care. If your veterinarian detects a heart murmur in your dog, it's essential to follow their guidance and treatment recommendations to ensure the best possible outcome for your furry companion. Regular veterinary check-ups and a loving, supportive home environment can go a long way in helping your dog live a fulfilling life despite the presence of a heart murmur.