Aortic/Subaortic Stenosis in Dogs

Aortic and subaortic stenosis (SAS) in dogs is a serious congenital heart condition that affects the heart's ability to pump blood efficiently. This article provides a detailed overview of the condition, treatment options, hereditary factors, prognosis, and frequently asked questions to help dog owners understand and manage this disease effectively.

What is aortic/subaortic stenosis in dogs?

Aortic stenosis and subaortic stenosis are forms of heart disease in which the aortic valve or the area below it narrows, obstructing blood flow from the heart to the body. The severity of stenosis can range from mild to severe, and more severe cases can lead to heart failure or sudden death.

• Aortic stenosis (AS): Narrowing of the aortic valve, which restricts blood flow from the left ventricle to the aorta.
• Subaortic stenosis (SAS): A most common form in dogs, where fibrous tissue develops under the aortic valve, causing an obstruction.
  
  

Causes and Risk Factors

The main cause of subaortic stenosis in dogs is genetic inheritance. Certain breeds are predisposed to the condition, including:

• Golden Retrievers
• Rottweilers
• Newfoundland
• Boxers
• German Shepherds
• Great Dane
• Bullmastiffs
  
  

This condition is usually diagnosed in puppies or young dogs, and symptoms worsen over time. Other risk factors include:

• Congenital heart defects: Some dogs are born with heart defects that contribute to the development of SAS.
• Environmental factors: While genetics play an important role, certain environmental factors during fetal development can increase the risk.
• Nutrition and prenatal care: Poor prenatal care can sometimes contribute to congenital heart problems.

Categories of Aortic Stenosis

Aortic stenosis is classified according to severity:

1. Mild: Minimal obstruction with no significant symptoms. Dogs can lead normal lives without intervention.
2. Moderate: Noticeable heart murmurs and increased risk of complications, requiring medication and monitoring.
3. Severe: Significant obstruction leading to heart failure, fainting, and sudden death, often requiring surgical intervention or intensive medical treatment.

Symptoms of Aortic/Subaortic Stenosis in Dogs

Many dogs with mild SAS may not show symptoms. However, in moderate to severe cases, signs include:

• Exercise intolerance
• Fainting (syncope), especially after activity
• Shortness of breath (dyspnea)
• Fatigue and lethargy
• Coughing, especially after exertion
• Irregular heartbeat (arrhythmias)(Related:Dog's normal heart rate)
• Sudden collapse or death in severe cases

How does SAS affect a dog's daily life?

A dog with mild to moderate SAS can continue to enjoy a relatively normal life, but with certain restrictions:

• Limited strenuous exercise: High-intensity activities can worsen symptoms.
• Regular follow-up: Routine visits to the vet help keep track of the progression of the condition.
• Dietary adjustments: Reducing sodium intake and maintaining a heart-healthy diet can help manage symptoms.

Diagnosing Aortic/Subaortic Stenosis

Veterinarians diagnose SAS through:

• Auscultation: Detecting heart murmurs with a stethoscope.
• Echocardiogram: The most accurate method of assessing the severity of stenosis by measuring blood flow and heart function.
• Electrocardiogram (ECG): Detects abnormal heart rhythms.
• Chest X-rays: Evaluates the size of the heart and lung health.
• Doppler ultrasound: Measures blood velocity and turbulence.

When should you seek veterinary help?

If your dog exhibits symptoms such as frequent fainting, shortness of breath, or exercise intolerance, an immediate veterinary evaluation is recommended.

Treatment of Canine Subaortic Stenosis

There is no cure for SAS, but treatments focus on controlling symptoms and improving quality of life.

Drugs

• Beta-blockers (e.g., atenolol, propranolol): Reduce heart rate and oxygen demand, which helps control obstruction of blood flow.
• Angiotensin-converting enzyme (ACE) inhibitors (such as enalapril, benazepril): Lower blood pressure and reduce the workload on the heart.
• Antiarrhythmic drugs: help control irregular heartbeats, preventing sudden cardiac events.
• Diuretics: Reduce fluid buildup in cases of heart failure.

Surgical and Interventional Procedures

• Balloon valvuloplasty: A minimally invasive procedure to widen the narrowed area using a catheter and balloon.
• Open-heart surgery: This is rarely done, but it may be considered in severe cases when other treatments fail.
• Pacemaker implant: Used to control severe arrhythmias and heart blocks.

Lifestyle adjustments

• Exercise management: Avoid high-intensity activities that strain the heart.
• Dietary modifications: A heart-healthy diet, often low in sodium, can help maintain optimal cardiovascular function.
• Routine veterinary visits: Regular check-ups to monitor progression and adjust treatment accordingly.

Is aortic stenosis hereditary?

Yes, aortic stenosis is an inherited condition, especially in breeds prone to congenital heart defects. Responsible breeding practices and genetic screening can help reduce the prevalence of this disease. Breeders should examine dogs for heart murmurs and perform echocardiograms prior to breeding.

Life expectancy of a dog with subaortic stenosis

The prognosis depends on the severity:

• Mild cases: Dogs can live a normal life with minimal complications.
• Moderate cases: Life expectancy may be shortened, but treatment may improve quality of life.
• Severe cases: Many dogs succumb to heart failure or sudden death before the age of three.

Final stages of aortic stenosis in dogs

In the final stages, symptoms worsen and may include:

• Severe exercise intolerance
• Frequent fainting episodes
• Shortness of breath and cough
• Congestive heart failure causing fluid buildup in the lungs

How quickly does aortic stenosis get worse?

SAS is a progressive condition. In some cases, symptoms gradually worsen, while in others, there is a sudden deterioration due to arrhythmias or heart failure.

Can aortic stenosis cause sudden death?

yes. Severe aortic stenosis increases the risk of fatal arrhythmias, which lead to sudden death without warning. Many cases occur during physical exertion or stress.

What happens if the stenosis is not treated?

Without treatment, dogs with moderate to severe stenosis face a high risk of heart failure, collapse, or sudden death. Early diagnosis and treatment are crucial.

FAQ 

What are the warning signs of aortic stenosis in dogs?

Key warning signs include fainting, exercise intolerance, labored breathing, and a heart murmur detected during routine exams.

Can aortic stenosis be cured in dogs?

No, but treatment can control symptoms and extend lifespan.

What is the cost of treating aortic stenosis in dogs?

Costs vary depending on the type of treatment:

• Medications: $50–$200/month
• Echocardiogram: $500–$1,500
• Balloon valvuloplasty: $3,000–$7,000

How often should a dog with SAS visit the vet?

Dogs with SAS should be checked every 6 to 12 months, or more frequently for severe cases.

Can a dog with aortic stenosis lead a normal life?

Mild cases may not affect life expectancy, but moderate to severe cases require careful management to improve longevity and quality of life.

By understanding aortic/subaortic stenosis in dogs, pet owners can take proactive steps to manage the condition and improve the well-being of their furry friend. Early diagnosis, proper treatment, and regular veterinary care are key to improving outcomes for affected dogs.