dog wheezing at vets office getting checked for heart disease in dogsCongestive heart failure in dogs is a common heart condition that affects many dogs. Although certain dog breeds like the Doberman are prone to congestive heart failure, any dog can, in fact, develop this heart problem. The heart is a muscular pump that pushes blood around the body. This vital function supplies blood to all organs.

When the heart is damaged in some way, it no longer pumps effectively. Happily, the heart and circulation can cope up to a certain point by making adjustments. When it passes the point of being able to adjust further, signs of congestive heart failure develop.  To learn more about congestive heart failure in dogs read on!

What is Congestive Heart Failure in Dogs?

Let’s start at the beginning: What is “congestive heart failure in dogs”?

Often abbreviated to CHF, congestive heart failure in dogs occurs when the heart is struggling to pump effectively. There are many reasons why the heart should fail in this way. Typical causes of congestive heart failure in dogs include:

  • leaky heart valves
  • a disease of the muscle of the heart wall
  • physical pressure squashing the heart, and
  • problems with the electrical pathways

The most common consequence of congestive heart failure in dogs is fluid buildup in the body. The symptom most people are aware of is a cough. This cough is due to fluid accumulating in the lungs. However, heart failure is more complicated than this.

Left-Sided Heart Failure Vs Right Sided Heart Failure

There are two sides to the heart. In simple terms, left-sided heart failure causes a cough. Right-sided heart failure is responsible for fluid pooling in the belly.

But heart failure is rarely this neatly defined. Many dogs show signs of mixed failure, involving both the left and right heart.

Fluid Around Heart: Causes of Heart Failure in Dogs

Another cause of congestive heart failure in dogs is pressure pushing down on the heart. This is caused by fluid buildup between the pericardium (the tough sac in which the heart sits) and the heart muscle. The pericardium cannot stretch, so as fluid accumulates, it squashes the heart.

The compressed heart cannot then fully relax. This stops the chambers filling with blood. Then when the heart contracts, only a small volume of blood is pushed into the circulation.

This form of CHF is known as pericardial effusion. The cause often cannot be identified, this is known as idiopathic. Sadly, a major cause of pericardial effusion is a tumor at the heart base.

xray of enlarged heart in dogs body

Enlarged Heart in Dogs: Could Enlargement of the Heart Cause Congestive Heart Failure?

You may have heard the vet refer to an ‘enlarged heart’. This is a general term that describes heart size on radiography. But the size of the heart shadow gives no information about what’s happening in the heart chambers. A cardiac ultrasound scan is then required to ‘see inside’.

Heart enlargement can be down to one of a number of causes. Identifying the cause matters because alters the treatment. Causes of heart enlargement include:

  • Dilated cardiomyopathy: A disease affecting the heart muscle which becomes weak and baggy. This condition is unfortunately very common in English bred Doberman Pinschers.
  • Pericardial effusion: Fluid around the heart enlarges the silhouette. Golden retrievers seem especially predisposed to this.
  • Compensatory mechanisms: The diseased heart has to work harder, which eventually leads to stretching of the heart chambers. This can happen to any dog with heart disease

Enlarged Heart Symptoms in Dogs: Abnormal Dog Heart Rate, Dog Breathing Heavy, Etc…

Although congestive heart failure occurs for different reasons, the symptoms are often identical.

It’s often not possible to precisely diagnose what’s wrong with the heart from the symptoms alone. General signs of CHF in dogs include:

  • Lack of energy
  • Unwillingness to exercise
  • Heavy panting at rest
  • Rapid breathing
  • Abnormal heart rate for dogs
  • Racing heart
  • Lack of appetite
  • Coughing
  • Restlessness
  • Weight loss
  • Fainting episodes

If you see any of these signs, get your dog checked by a vet.

Types of Heart Failure and Heart Disease in Dogs

Understanding the type of heart failure is important when selecting treatment.

Be alert for changes in your dog, such as a lack of interest in walks or coughing at night. Although not diagnostic in themselves, it gives the vet vital clues for further investigation.

Dog Wheezing or Dog Breathing Fast? Signs of CHF in Dogs/Dog Heart Murmur

The classic sign most people associate with congestive heart failure in dogs is a cough. This tends to be worse when the dog is resting. This is because moving around causes contraction of the skeletal muscles, which aids the circulation a little. Thus, a night-time cough in a dog known to have a heart murmur needs to be taken note of.

Earlier we mentioned the two sides of the heart. It’s the vet’s job to work out which type of failure is occurring, so don’t get too hung up on the details. For your interest:

Right-Sided Heart Failure Symptoms

It is the job of the right heart to push deoxygenated blood into the lungs. When the right heart tires, it causes a problem downstream. In practical terms, blood returning from the body to the heart doesn’t get distributed to the lungs fast enough. Like a log-jam in a river, this cause pressure to build up downstream.

The classic sign of this happening in right-heart failure is fluid building up in the belly. This may give the dog a pot-bellied appearance. But be aware, a pot belly can develop for other reasons, not just right-heart failure. So a trip to the vet is essential.

Left-Sided Heart Failure Symptoms

The left heart is responsible for pushing blood returning from the lungs (rich in oxygen) around the body. This time downstream from the left-heart are the lungs. A buildup up of blood in the lungs causes fluid to leak out. It is this fluid that enters the lungs and causes a cough. This fluid is known as pulmonary edema.

Regardless of the type of heart failure, the same general symptoms apply. The main ones to watch out for are lack of energy and rapid breathing.

The best time to judge is the dog is breathing quickly, is to watch them at rest. Look carefully at the rise and fall of the ribs. A normal respiratory rate at rest is around 20 – 30 breaths. More than this and the dog is breathing rapidly. It’s helpful to video this on your phone to show the vet. This helps because the stress of a veterinarian visit makes most dogs pant anyway, making diagnosis harder.

dog heart diagram of congestive heart failure in dogs

Diagnosis of CHF in Dogs

The first step in the diagnostic tree is for the vet to examine the patient. They will watch the dog breathing at rest before undertaking a physical examination. Whilst the vet may have a suspicion of CHF from the dog’s history and presentation, they won’t assume anything.

The reason behind a thorough physical exam is so as not to miss anything. It might be the dog’s swollen belly isn’t due to fluid retention because of a heart problem, but an endocrine disorder such as Cushing’s disease or even a splenic tumor.

Once the vet has finished looking at the dog’s mucous membranes and feeling the belly, they will listen to the heart. To do this they listen with a stethoscope to the heart sounds in various places over the chest. It’s also important to listen to the right and left-side of the heart, to try and localize the problem.

The vet listens to the heart sounds, rate, and rhythm. This gives the vet clues as to whether the problem is with the valves (and if so which valves) or maybe a congenital problem.

Congenital problems are those problems present at birth. They can include the way the major blood vessels are plumbed into the heart (for example a subaortic stenosis or patent ductus arteriosus) or heart formation (such as an atrial septal defect).

Based on their findings, the vet will decide on which tests will be most useful to make a diagnosis. There are several options, of which the most useful is cardiac ultrasound.

Cardiac Ultrasound

You may be familiar with ultrasound as the tool used to monitor a growing baby in the womb. That same ability to visualize internal structures is hugely valuable when studying the heart.

The beauty of ultrasound is that the operator can see inside the heart and watch, in real time, how the heart contracts. Not only that, but color-flow techniques allow the vet to spot jets of blood flowing in the wrong direction.

Seeing so much detail inside the heart also means it’s possible to take measurements. The vet learns invaluable information from the thickness of the heart walls and the dimensions of the heart chambers themselves. Indeed, the ratio of these measurements is now used to decide the best time to start certain medications such as pimobendan (Vetmedin).

EKG

An EKG is a vital tool for monitoring the heart, especially when the patient undergoes a general anesthetic. However, it is of limited use for diagnosing heart disease. As a diagnostic tool, cardiac ultrasound has largely overtaken an EKG in terms of usefulness.

The place of EKG is strongest is in diagnosing heart rhythm disturbances. These are the conditions caused when the nerves that tell the heart muscle when to contract or relax, don’t fire at the right times.

Chest Radiographs

The strength of x-rays is in showing the pattern of fluid retention in the lungs. This helps the vet decide between pulmonary edema and pneumonia, both of which can cause a cough.

Chest x-rays also tell the vet if the heart is physically larger than expected. However, it gives no information about the cause of that enlargement, which could be due to stretched heart chambers or fluid around the heart.

Dog Congestive Heart Failure: When to Put Down or Possibly Treated

Whilst heart failure cannot be ‘cured’ it can be managed. The effective use of heart medications can improve the dog’s quality of life, and often extend life expectancy.

The drugs most commonly used are ace-inhibitors, such as enalapril; pimobendan which goes by the name of Vetmedin, and diuretics. The latter are commonly known as ‘water tablets’ as they help shift fluid that has built up on the lungs or belly.

Enalapril for Dogs

Ace-inhibitors  (angiotensin-converting enzyme inhibitors) such as Enalapril, help by taking some of the resistance to blood flow out of the circulation. Enalapril has the effect of opening up small blood vessels in the periphery of the circulation, which helps blood flow more easily. Think of this like unblocking the kitchen sink, so that water can flow out more freely.

Another benefit of enalapril is that it subtly changes the blood pressure gradient across vital organs such as the kidney. This improves the circulation to the kidneys, which is often compromised when the heart is failing.

Vetmedin for Dogs

Pimobendan in dogs has become a game changer for those with heart murmurs.

Research has now proven that starting Vetmedin at the right time can greatly extend life expectancy. Importantly, the ideal stage can only be diagnosed by taking measurements during a cardiac heart scan.

That sweet spot for starting Vetmedin is when a dog has a quiet murmur and the heart is just starting to use its compensatory mechanisms. A clue to this is seeing an enlargement of the heart chambers on a scan, but the dog doesn’t yet have any clinical signs.

Timing is everything so what many vets now recommend is that dogs with quiet murmurs have a check scan every 6 – 12 months.

Enlarged Heart: Congestive Heart Failure Stages of Dying

A diagnosis of heart disease is not the same as complete heart failure. There are many stages in-between, which can be managed with appropriate medication.

Ultimately, when the dog does enter terminal heart failure, then it is most humane to let that pet go. These dogs are usually very unwell, not eating, extremely breathless, and with little interest in play or exercise.

doctor checking for heart murmur in dogs body

Congestive Heart Failure Life Expectancy: How Long can a Dog Live with Congestive Heart Failure

Whilst a diagnosis of congestive heart failure is distressing, many dogs do lead a good quality life for months or years to come. All dogs are individuals and there is no one-size-fits-all rule when it comes to life expectancy. The person best placed to advise on what to expect is the vet who made the diagnosis.

However, be aware that you can help your dog. Factors such as managing their weight, keeping them slim, and keeping the dog fit all contribute to reducing strain on the heart.

Common Questions on Congestive Heart Failure in Dogs