Canine Congenital Heart Diseases are abnormalities or defects of the cardiovascular system (of the heart) that are present in the womb and remain at birth. The results of genetic or hereditary defects, infections, environmental conditions, or medications taken by the mother. The result of poisoning or poor maternal nutrition and in some cases a combination of these factors that may develop later in the dogs life. The most common defects are Aortic Stenosis, Pulmonic Stenosis and Patent Ductus Arteriosus. Without treatment these conditions and other Congenital Heart Diseases can lead to a variety of problems including Congestive Heart Failure.
Types of Congenital Heart Disease in Canines (CHDs)
The three most common CHD’s are
Patent Ductus Arteriosus
Less common CHD’s are
Atrial Septal Defect
Canine Dilated Cardiomyopathy
Mitral Valve Dysplasia
Persistent Right Aortic
Tetralogy of Fallot
Tricuspid Valve Dysplasia
For information on Congestive Heart Disease see further below
To understand stenosis, you must first have a basic understanding of heart anatomy. The heart has two sides, left and right.
The right side receives the deoxygenated blood carried from the body and then pumps it to the lungs to be oxygenated.
The left side of the heart receives oxygenated blood from the lungs and then pumps it to the body to be used by the bodies muscles and important organs such as the liver, kidneys etc.
As the blood is pumped from the left ventricle it must pass through a special gate called the aortic valve.
In Dogs and Humans with Subaortic Stenosis, the area at the base of the aorta just below the aortic valve (subaortic) is constricted (narrowed).
This is referred to as Stenosis and is caused by a ring of fibrous tissue that has formed in this area. A bit like squeezing the garden hose pipe, it would reduce the flow of water to the sprinkler.
Experiment: If you are under 18 please get adult supervision. – Take a rubber band and wrap it around your finger. The blood flow will be restricted to and from the finger tip, it will redden in colour and you will begin to feel your fingertip pulsing because of the back pressure within the fingertip – this is how the heart will feel and long term would cause problems – your finger would also suffer long term if you left the rubber band on so be sure to remove the elastic band after just a few minutes.
This heart problem typically gets worse over time because the restriction gets tighter causing a serious lack of flow to the body via the aorta and creating back pressure in the left ventricle of the heart which means it has to overwork (strain) to keep up normal supply (increasing the chance of heart stroke/failure).
Pulmonic Stenosis (PD) is essentially the opposite of Aortic stenosis and obstructs the flow of blood to the pulmonary artery from the right ventricle. As such it interferes with the flow of blood between the lungs and heart, clearly a dangerous prospect if the blood cannot reach the lungs to be oxygenated.
This defect is frequently found in breeds such as Boxers, Bulldogs, Boston Terriers, Labrador Retrievers, Samoyeds, Russell Terriers, and Newfoundland’s.
Patent Ductus Arteriosus (PDA)
This condition can affect any breed of dog but is more prevalent in females.
As an embryo develops within the womb, some of the embryo’s own vital organs are not needed for their normal function. So some of the blood vessels in the embryo bypass the usage of certain organs only giving them enough blood to develop until the foetus is separated by birth from its mother.
The lungs are an obvious one as breathing is not required whilst the embryo is growing in the sac. Thus the organs that are not necessary to the embryo at this time are circumvented (bypassed) by a vessel called the “ductus arteriosus,” this shunts (moves) blood from the pulmonary artery which would normally supply blood to the lungs and instead pumps it to the aorta.
In any new-born animal, this temporary structure is expected to close within the first few weeks of life so that the blood can move directly to and from the lungs, thereby receiving any necessary oxygen the body needs to carry out its normal functions.
It is when this temporary blood vessel remains OPEN, (essentially leaking), that the resulting disease occurs and is referred to as “patent ductus arteriosus” or “PDA.”
If this occurs, the change of pressure in the heart, can result in a reversal of blood flowing through the still open or leaking blood vessel (from the aorta to the pulmonary artery), this then allows increased blood to flow to the lungs or, less commonly, the blood can flow in the opposite direction through the blood vessel.
Too much blood in the lungs means fluid build-up between the heart and lung. Too much blood in the left side of the heart means the heart has to work harder (increased chance of heart stroke/failure).
Either way both problems mean this disease will eventually end in heart failure, generally within the first two years of life. Treatment of some kind is a must if your dog is to survive long term.
A Note of Hope
Although canine heart diseases can be serious and often life-threatening, there are many treatment options available that can help your dog live a high quality and long life.
Drugs, diet therapy, therapeutics, and activity modification are strategies used in treating CHD’s in dogs. Your vet can help you to selecting the best treatment and /or therapy for your dog.
Atrial Septal Defect
This condition is commonly known as a “Hole in the Heart”. There will be a hole or a defect in the separating wall between the left and right atrium of the heart.
If your dog has Atrial Septal Defect, it has a defect or hole in the wall separating the left and right atrium of the heart. The heart consists of four chambers, and the left and right atria are the two of them.
The walls between the rooms of the heart muscle are called the septal. When the dog is still embryonic heart starts of as a single tube. During its growth toward being a new born puppy the heart will then gradually separate into four chambers just before the puppy is born.
This handicap can grow at different stages of the growing process, and the result can be small or large defects in the Atrial Septal of the dog’s heart.
Canine Congenital Heart Disease
The most common types of congenital heart disease in dogs include:
- Congestive Heart Failure (CHF)
- Canine Dilated Cardiomyopathy (CDC)
- Pulmonic Stenosis (PS)
Congestive Heart Failure (CHF) Also known as Congestive Heart Disease
Congestive Heart Failure or CHF occurs when the dog’s heart cannot pump adequate blood throughout his body. CHF can also cause increases in pressure and fluid within the heart, which can potentially leak into the lungs, negatively impacting your pet’s breathing.
CHF may affect one side of the animal’s heart or both sides. The condition progresses slowly and can take years to manifest or spot if you do not know the symptoms.
Canine Dilated Cardiomyopathy (CDC)
Canine Dilated Cardiomyopathy affects the cardiac muscles. CDC impacts the heart’s ability to generate enough pressure required to pump blood throughout the dog’s vascular system. Although it has been suggested that Canine Dilated Cardiomyopathy is genetic, it can also be caused by other factors such as infections and nutrition.
Breeds like Cocker Spaniels, Boxers, and Great Danes are more predisposed to CDC.
Pulmonic Stenosis (PS)
Symptoms of Congenital Heart Failure
Heart disease in dogs may result in congestive heart failure (CHF). That’s when your dog’s heart has trouble pumping enough blood to the rest of the body.
Knowing the symptoms of congenital heart disease can be crucial in getting your furry companion the medical help they need. Problematically the symptoms of congenital heart defects vary depending on the severity and type of heart disease involved.
Common signs include difficulty breathing, shortness of breath, coughing, fatigue, fainting, or a build-up of fluid in the abdomen or lungs.
Common signs of congestive heart failure are persistent coughing, often accompanied by difficulty in breathing. Fluid accumulation in the lungs leads to an enlarged heart that can then create pressure against the trachea. This is an irritation which can induce a cough.
Many dogs with congenital heart failure also have reduced stamina, i.e. they tire out quickly, and will not engage in walking or playing as they did before attaining the condition.
Other signs of CHF are coughing when sleeping or at rest, excessive panting, a swollen belly, persistent loss of appetite, and one particularly easy sign to look for is bluish or pale gums.
If any of these signs are present in your pet, you should immediately get in touch with your veterinarian.
Diagnosing and Detecting Heart Disease in Dogs
Diagnosing heart disease in dogs entails combining several different methods. Often, a physical exam can pick up a heart murmur (turbulent movement of blood) or abnormal heart rhythm (arrhythmia). An ECG and imaging tests like X-rays or an ultrasound of the heart (echocardiogram) may be necessary to establish the specific type of heart disease type.
Heart failure is a syndrome in which a severe dysfunction leads to failure of the cardiovascular system. If your dog is suffering from heart failure the bodies system is unable to maintain enough blood circulation throughout the animal’s body. Dogs with long term heart defects will develop generalized muscle wasting and weight loss and possible dank hair or loss of it in places.
However, not all dogs with heart disease will end up developing heart failure. The prevalence of congenital heart disease in dogs is estimated at below 1%. It is, therefore, crucial to differentiate between congenital heart disease and heart failure for proper diagnosis and treatment.
Treating Heart Disease in Dogs
Since heart disease is a broad umbrella term for many conditions that interfere with the heart’s functioning, treatments are broad and wide-ranging. Heart disease in dogs can be managed or treated through prescription drugs, supplements, diet changes, and if needed surgical intervention depending on the severity and specific condition.
The goal of treating congestive heart disease or failure is to increase blood flow to the heart, lungs, and other parts of the body and reduce fluid build-up. Such treatments are designed to help improve the length and quality of the life of your pet.
Often, once a dog has been diagnosed with CHF, they may have to take medication for life. Sometimes the treatment regime is initiated during a short stay in the pet hospital with follow-up visits. Other times, the veterinarian may feel comfortable with simply allowing treatment at home.
The medications or therapy chosen will depend on the type and severity of the heart disease and the pet’s overall health. The veterinarian may, at times, decide to have the animal wear a monitor for several days that records the irregular heartbeats. Although not very common, some forms of canine heart disease may require surgery.
Caring for a Dog with CHD at Home
At home, dogs with heart disease need monitoring and special care. Proper monitoring of your dog at home may help delay CHF onset and help alert you if the condition worsens. General activity, water intake, appetite, behavior, and general activity should be closely monitored.
Although heart disease can be serious, there are many treatment options available to help your pet not just control the symptoms but enjoy a higher quality of life. These include diet therapy, therapeutics, and modification of activity. Your vet can help you choose the best therapies for your four-legged pal.
Your vet can help you know what symptoms to look for and monitor. Ensure you follow the instructions from your veterinarian.