If your dog becomes lethargic and develops a cough, it could be a sign of heart disease. In this post, you’re going to learn exactly what are the causes of congestive heart failure in dogs. This guide also includes lots of advice on testing, diagnosis and treatment. Let’s dive right in!
What is Congestive Heart Failure?
Congestive heart failure (CHF) is a term that refers to the heart’s inability to pump adequate blood to the body. There are many causes of CHF in dogs. The two most common reasons are:
- Mitral valve insufficiency (MVI). MVI is a leaky mitral valve, which is the valve between the left atrium and the left ventricle.
- Dilated cardiomyopathy (DCM).
What is Heart Disease?
A very complicated subject but some necessary information allows understanding and what to look out for! The heart is a pump, consisting of four chambers; the right atrium and ventricle and the left atrium and ventricle. The atria and ventricles are separated by the mitral valve on the left side and the tricuspid valve on the right. These valves stop the backflow of blood. The right side of the heart pumps deoxygenated blood that has returned from the body through the pulmonary artery into the lungs, where it is oxygenated (if the lungs are functioning correctly).
The oxygenated blood then returns to the left atrium before being pumped by the left ventricle to the body. Most commonly in older dogs, heart disease occurs as a result of valve or cardiac muscle problems.
Heart disease causes blood to be pumped less effectively around the body, leading to inadequate blood supply to muscles and organs. Fluid can also back up in a dog’s lungs or abdomen. This can lead to congestive heart failure and can affect one or both sides of the heart.
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Left-Sided Heart Failure
Damage to the mitral valve allows the backflow of blood from the left ventricle to the atrium and consequent poor tissue perfusion initiating a change of events that at first helps maintain blood pressure but ultimately causes more damage. Fluid retention in the lungs is the result. Signs to look for:
- Increased respiratory rate (tachypnoea)
- Difficulty breathing (dyspnoea)
- Exercise intolerance
- Collapsing or fainting
- Increased heart rate (tachycardia)
Right-Sided Heart Failure
Less often, the tricuspid valve is affected. (Although Labradors can have a malformation of the valve; a condition called tricuspid valve dysplasia, which causes a murmur to be audible high up on the right side of the chest. Puppies should be checked for this). In right-sided failure, fluid builds up in the abdomen, and the liver is enlarged. Signs to look out for:
- Abdominal distension
- Exercise intolerance
- Weight loss
Dog Breeds with Heart Problems
Heart disease is quite common, especially in older dogs, and is also quite common in certain breeds, such as the Cavalier King Charles Spaniel, Boxer, Great Dane, and Dobermann Click To Tweet So, what are the causes of congestive heart failure in dogs? There are several causes for heart disease in dogs, and these may be congenital, inherited, or degenerative.
Causes of Congestive Heart Failure in Dogs
The most common disease, especially in smaller breeds, is mitral valve disease (MVD). With this disease, there are changes to one of the four sets of valves in a dog’s heart. As the mitral valve degenerates, it no longer fully closes with each pumping action and allows some blood to leak back into the atrium as the ventricle contracts. This turbulent blood flow is heard as a whooshing sound, instead of an apparent “lub-dub” heartbeat. Vets call these abnormal sounds heart murmurs. Heart murmurs are graded according to severity, from grade I (barely audible) to grade VI (very loud).
Heart Muscle Damage
In larger dogs, heart failure can be caused by dilated cardiomyopathy (DCM), where the ventricles (lower chambers of the heart) can become enlarged and weakened, and mostly affects one side of the heart more than the other. Essentially, the muscle becomes limp and useless as a pump. Unfortunately, the prognosis is poor.
What are the Symptoms?
Early symptoms of heart disease include lethargy, tiredness, muscle weakness, reduced activity, and later in the course of the illness, collapse.
Many owners will report that their dog has a funny cough, that sounds like the dog has something stuck in his throat. This cough can be caused by fluid collecting in the lungs as the heart struggles to pump blood effectively, or it may be caused by an enlarged heart pushing on the windpipe. This cough can get worse after exercise, or if the dog gets over-excited.
In some cases, the dog will have an enlarged abdomen caused by fluid collecting in the liver or abdominal cavity.
Testing and Diagnosis
Signs of heart failure can include a fast, weak pulse, and poor circulation. Your vet will listen to your dog’s chest with a stethoscope for abnormal sounds like murmurs, which can indicate fluid in the lungs. Vets can also press on the dog’s gums and see how quickly the colour returns – in healthy dogs, the colour should return within three seconds, but can take longer in dogs with heart disease, due to poor circulation.
Your vet should take x-rays of your dog’s chest to look for fluid in the lungs, and to assess the size of the heart.
An ultrasound will allow the vet to assess the heart’s chambers, valves, walls, and blood flow.
What Treatment is Available?
There are many medications available to treat and control heart murmurs. Standard treatment for MVD is angiotensin-converting enzyme (ACE) inhibitors, which can help reduce the resistance in the circulation in the body, which eases the heart’s workload. Diuretics reduce circulating blood volume and reduce fluid in the lungs and abdomen. Pimobendan is a drug with multiple effects on the heart, including helping it to beat more powerfully. Some congenital problems, such as patent ductus arteriosus (PDA), can be cured with surgery.
Depending on the severity of the disease, and the causes of congestive heart failure in dogs, they can live relatively healthy lives for months, or even years, with medication and monitoring. Sadly, there is no cure for most heart diseases, so it is a matter of making your dog’s life as comfortable as possible.
How You Can Help
Your vet may suggest a diet that is low in sodium, and his diet may be restricted when it comes to treats, as many contain high amounts of salt.
You need to watch your dog closely when he is exercising to make sure he doesn’t overdo it. If he starts panting or slows down, make sure he gets plenty of rest. Speak to your vet about adjusting your dog’s walk and exercise plan to make sure he gets just the right amount of exercise to keep him healthy, but doesn’t put too much strain on his heart.
The most important thing is to be vigilant and keep an eye out for changes in your dog’s breathing, behaviour, appetite, activity levels, and the amount of water he drinks. If your dog’s condition changes or worsens at any time, go and see your vet straight away.
Heart Disease vs Chronic Bronchitis?
It may well be that your dog is nor suffering from heart disease but has chronic bronchitis instead. A vet can diagnose this when there has been coughing on most days over two months. A variety of causes, including passive tobacco smoke exposure (PTSE), previous respiratory infections and pure bad luck conspire to cause chronic inflammation of the airways, leading to increased mucus production and poor performance of the cilia (the little hairs that continually waft mucus out of the lungs).
It is worth stating that the results of a four-year study at the Animal Medical Centre of Nihon University, Kanagawa, Japan, showed that PTSE made virtually every canine respiratory condition worse. While it is likely that PTSE actually causes damage, it is evident that it exacerbates pre-existing lung and heart conditions.
As a result, the tiny airways, called bronchioles, become plugged and thicken. Dogs are usually bright, but there is a chronic cough (with occasional production of white foam), and exercise tolerance is reduced. Sometimes wheezing or crackling can be heard.
Steroids, antibiotics and bronchodilators can help, but care should be used with anti-cough medicine because this can cause a dangerous build-up of mucus in the airways. It is preferable to only use it at night to allow rest. Remember there are many other lung diseases caused by (for example) allergy, parasites and tumours. Please consult your vet for a full diagnosis.
Vets can differentiate between the common causes of coughing in older dogs. Obviously, most youngsters present with infectious coughs, but geriatrics can be affected by lung and heart problems. If your old dog is coughing, have a heart and take them for a check-up.
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I hope this article helped you to understand the causes of congestive heart failure in dogs. If you have any questions or comments, please leave them below, and I will get back to you as soon as possible.