Congenital heart defects are abnormalities that affect the heart’s structure or function. When a defect is called congenital, this means it is present at birth. Other heart defects exist that are acquired. This means they develop later in life. Congenital defects can range from minor to very severe. The impact they have on your dog’s health can vary greatly. Luckily for our canine companions, there have been significant advancements in diagnosing and treating heart defects in recent years. This article will discuss congenital heart defects and how they are treated, read on to find out more! 

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What is a congenital heart defect in dogs ? 

A congenital heart defect is an abnormality present at birth that affects the structure or function of the heart. The defect can involve abnormalities in the heart’s blood vessels, chambers, or valves. It can also be a combination of a few different things present at the same time. 

There are many different types of congenital heart defects. Some of the more common include:

Patent ductus arteriosus: 

This is one of the most common congenital heart defects. It occurs when the ductus arteriosus, a blood vessel that bypasses the lungs in foetal circulation, doesn’t close when the pup is born. 

Subaortic stenosis: 

This is a condition where the opening of the aorta, the largest artery in the body, is narrowed. The narrowing that occurs makes it more difficult for blood to flow out of the heart. This can put extra strain on the heart muscle as it pumps. 

Pulmonic stenosis: 

This is a condition where the opening between the right ventricle (one of the 4 chambers of the heart) and the pulmonary artery (a blood vessel leading to the lungs) is narrower than usual. This narrowing makes it more difficult for blood to flow from the heart to the lungs.

Ventricular septal defect: 

This is another congenital heart defect, sometimes known as a “hole in the heart”. Here, there is a literal hole in the wall that separates the heart’s lower chambers, the ventricles. The wall is called a septum. This hole through the septum allows blood to flow from the left ventricle, which pumps oxygenated blood to the body, into the right ventricle, which pumps deoxygenated blood to the lungs.   

Atrial septal defect: 

Another type of “hole in the heart”, this defect occurs when an opening between the right and left atrium (the two upper chambers of the heart) is present. The opening allows blood to flow abnormally between the left and right atria.  

Tetralogy of Fallot: 

This is a rare and complicated heart defect. There are four separate abnormalities present in this disorder. These are: 

  1. Ventricular Septal Defect – A hole in the wall (septum) between the two lower chambers of the heart (ventricles).   
  2. Pulmonic Stenosis – Narrowing of the pulmonary valve, which controls blood flow from the right ventricle to the lungs.   
  3. Overriding Aorta – The aorta, the main artery carrying blood from the heart, sits on top of both ventricles instead of just the left ventricle.   
  4. Right Ventricular Hypertrophy – Thickening of the right ventricle’s muscle wall due to increased workload caused by the other three abnormalities.   

Clinical signs of heart defects in dogs

Clinical signs of congenital heart defects can vary greatly. Some dogs show no clinical signs at all. Others will have a bad cough, have become exercise intolerant and some may even present collapsed. There is some overlap of clinical signs with each defect and some differences. Your vet will be able to hear a heart murmur when they listen to your dog’s chest with a stethoscope. There are different types of heart murmur that they will be able to identify over different areas of the heart. 

Typical signs seen with a patent ductus arteriosus include: 

  • Breathing difficulties
  • Lethargy 
  • A heart murmur that is loud and continuous like a washing machine 
  • Exercise intolerance
  • Abnormal pulses 
  • Fluid build up in the lungs or abdomen 
  • Stunted growth 

Signs seen with subaortic stenosis include:

  • Exercise intolerance: 
  • Fainting episodes 
  • Heart murmur: A loud heart murmur can often be heard by your vet with a stethoscope. 
  • Stunted growth
  • Sudden death: In some cases, severe subaortic stenosis can cause sudden death.

Signs seen with pulmonary stenosis include:

  • Exercise intolerance
  • Fainting episodes, usually during exercise or if the dog is stressed.
  • Cyanosis: A bluish tinge to the gums and mucous membranes. (This occurs because there isn’t enough oxygen in the blood). 
  • Heart murmur: A harsh murmur can be heard when listening to the heart with a stethoscope. 
  • Stunted growth 
  • Poor weight gain

The signs seen with ventricular septal defect include:

  • Heart murmur
  • Exercise intolerance
  • Fainting episodes
  • Stunted growth 
  • Cyanosis
  • Lethargy 
  • Coughing

Signs seen with atrial septal defect include:

  • Heart murmur:
  • Exercise intolerance
  • Breathing difficulties 
  • Fainting episodes 
  • Stunted growth
  • Lethargy 
  • Cyanosis 
  • Coughing

Signs seen with Tetralogy of fallot include:

  • Cyanosis: 
  • Panting
  • Breathing difficulties 
  • Fainting episodes 
  • Exercise intolerance
  • Stunted growth:
  • Heart murmur
  • Lethargy
  • Decreased appetite

Treatment for heart defects in dogs 

There are lots of different treatment options for congenital heart defects. Your vet will need to take into account: 

  • The severity of the heart defect 
  • Your dog’s size
  • Your dog’s age. 
  • And your dog’s general health status and the presence of other diseases

They will also weigh up the risks and benefits of each treatment option.

Patent Ductus Arteriosus treatment

Surgery is the treatment of choice for this condition. The duct is tied off to prevent blood from flowing through it. In some cases, a less invasive procedure where a catheter is inserted into the artery and a coil or ductal occluder device is placed to block the ductus arteriosus.

For dogs with this defect, surgical repair should be carried out as soon as possible. If the surgery is delayed, the chances of irreversible heart damage will increase. If the dog is in heart failure already, they will need to be stabilised before the operation is carried out. 

Subaortic stenosis treatment

Treatment very much depends on the severity of the disease. In mild cases, your vet may recommend regular check-ups and monitoring of the dog’s heart health. In mild cases, a drug called a beta-blocker can sometimes be used to reduce the heart’s workload and improve blood flow. And in severe cases, surgical intervention may help.

Minimally invasive techniques have been described that involve putting a catheter with a balloon into the area of the valve. This is called a balloon valvuloplasty. When the balloon is blown up, it stretches the tissue around it. Other treatment options include a cutting balloon valvuloplasty.

Open resection has been attempted, however, this is very risky, and not many vet hospitals have the equipment to perform it. 

Ventricular septal defects treatment 

Depending on the severity of the defect, some cases do not require treatment and have a good prognosis. If a dog is showing symptoms, drugs can be used. This may include drugs like diuretics or bone marrow suppressants. Weight management, exercise restriction, and a specialised low-sodium diet are often recommended for dogs. 

Dogs with a more severe ventricular septal defect can be candidates for surgery. Surgical closure of the defect is a very tricky procedure. It can be done by open-heart surgery or in some cases a coil or occluder can be used. 

Pulmonary stenosis  treatment

In mild cases, your vet may recommend regular check-ups and monitoring of the dog’s heart health. Medication such as Beta-blockers can sometimes be used to reduce the heart’s workload and improve blood flow.

For severe cases of pulmonary stenosis, surgical repair may be necessary. Some options include:

  • Balloon Valvuloplasty:  A minimally invasive procedure where a catheter is inserted into a vein leading to the heart. The balloon is dilated to reduce the obstruction. 
  • Pulmonary valvotomy: A procedure where the narrowed pulmonary valve is surgically widened to improve blood flow.

Atrial septal defects 

If there is only a small atrial septal defect and the dog is not showing any symptoms, your vet may simply recommend regular check-ups and monitoring. Medications can be used in some cases to manage symptoms. 

If a larger defect is present, surgery may be required to close it. This can be done via open heart surgery, or as a minimally invasive approach, using a catheter. This is a very risky operation. 

Tetralogy of Fallot 

In mild cases, some dogs may be monitored without requiring immediate treatment. Some cases can benefit from medical management. Beta-blockers can be used to reduce the heart’s workload and improve blood flow. In some cases, diuretics may be prescribed to manage fluid buildup.

Surgery has been reported although it is not commonly carried out. Some palliative surgical techniques have been described that set out to relieve clinical signs but again, they are relatively rare.  

Prognosis for canine congenital heart defects 

The prognosis for dogs with congenital heart defects varies greatly depending on the type and severity of the defect present. Factors that will influence the prognosis include: 

The severity of the defect: 

More severe defects are generally associated with poorer prognosis. Defects that significantly impair blood flow or allow for heart failure to develop can pose greater challenges.

Early detection of the defect: 

Early diagnosis allows for prompt treatment and management which can improve outcomes. Identifying the defect before complications arise can make a huge difference. 

Appropriate treatment and management of the defect: 

The effectiveness of treatment, including choice of surgical interventions and medical management, will significantly impact the prognosis. 

Age of the dog: 

Some congenital defects are so severe they are not compatible with life. If a defect has not been noted until later in a puppy’s life then it may be less severe; however, the prognosis may also be poorer if other complications have occurred. 

Presence of concurrent diseases:

Additional health conditions, such as infections or other heart problems, can complicate the management of congenital heart defects and may affect the prognosis.

It’s important to note that even with a good prognosis, dogs with congenital heart defects may require lifelong monitoring and treatment. Regular check-ups and good communication with your vet are essential for ensuring the dog’s well-being and maximising their lifespan.

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Final thoughts 

Congenital heart defects in dogs are a complex group of conditions. While often severe, the good news is most of them can be managed with appropriate veterinary care. Early diagnosis and treatment are crucial for improving a dog’s quality of life and their lifespan. 

With a good understanding of the signs, causes, and available treatment options, owners can be better equipped to look after their canine companions. It’s important to remember that even with a congenital heart defect, lots of dogs can live happy and fulfilling lives. 

Sources and further reading