Written by Liza Cahn, DVM
As most pet parents can attest, dogs have big hearts. These adorable fur balls add so much love to our families, and in return, we must provide them with proper care. But despite our best efforts, heart disease is common in dogs, affecting nearly eight million dogs in the United States.
It is more common in older dogs, with up to 75% of senior dogs having some type of heart condition. Almost any type of underlying heart disease has the potential to lead to congestive heart failure.
What is Congestive Heart Failure?
The heart is a complex and very important organ. It pumps blood around the body to deliver nutrients and oxygen. This muscular structure is composed of four chambers, two atria on top and two larger ventricles below.
In healthy dogs, the right side of the heart pumps blood to the lungs, where oxygen is added to the blood and carbon dioxide is removed from it.
The left side of the heart pumps blood throughout the body to deliver oxygen and nutrients and remove other waste products. Several valves within the heart keep blood flowing in the correct direction.
Heart failure occurs when the heart is so severely diseased that it cannot pump enough blood to the body, failing to deliver essential oxygen and nutrients.
As heart failure gets worse, it can also cause blood to back up in the lungs or other organs, causing them to swell up with fluid. When this happens, a dog is said to be in congestive heart failure (CHF).
Congestive heart failure is a broad term. It can be caused by many different types of heart conditions, the most common being mitral valve insufficiency and dilated cardiomyopathy.
In early or mild cases of heart disease, a dog’s body can make up for a heart that doesn’t work well. However, as the disease gets worse, heart failure and the clinical signs of CHF appear.
Types of Congestive Heart Failure
Congestive heart failure can be classified as right or left-sided, depending on which side of the heart is most diseased.
Left-sided Heart failure
The left atrium collects oxygen-rich blood from the lungs, and the left ventricle pumps it to the rest of the body. In left-sided congestive heart failure, fluid backs up into the lungs (known as pulmonary edema) or chest cavity. This is the most common type of congestive heart failure in dogs.
Mitral valve disease, dilated cardiomyopathy, hypertrophic cardiomyopathy, and congenital heart defects are all types of heart disease that can cause left-sided failure.
cardiomyopathy, and congenital heart defects.
Common clinical signs include:
- Increased respiratory rate while resting or sleeping
- Exercise intolerance (tiring easily)
- Shortness of breath
- Coughing
Right-sided Heart Failure
The right atrium collects oxygen-depleted blood returning from the body, and the right ventricle pumps it to the lungs for gas exchange.
In right-sided congestive heart failure, fluid builds up primarily in the abdomen (known as ascites). Fluid may also leak from blood vessels in the limbs, causing a swelling known as peripheral edema.
Examples of heart disease that can lead to right-sided failure include tricuspid valve disease and heartworm disease. Common signs include:
- Swelling or enlargement of the abdomen due to fluid buildup
- Difficulty getting comfortable, decreased appetite, or difficulty breathing due to increased abdominal pressure, especially when lying down
Biventricular Heart Failure
If the ventricles on both sides of the heart are affected, then dogs may experience signs of both left and right-sided CHF.
Stages of Congestive Heart Failure
As heart disease progresses, it can also be classified into one of four stages.
Stage A
Dogs who are at high risk (based on breed and age) for developing heart failure. These dogs have normal functioning hearts and no clinical signs of heart disease.
Stage B
Dogs who have a heart murmur (heard by a vet when listening to the chest with a stethoscope) but no symptoms of heart disease.
Stage B2
Dogs with a heart murmur and no clinical signs, but with evidence of structural changes such as an enlarged heart.
Stage C
Clinical signs of heart disease are present, but they can be controlled with medications.
Stage D:
Dogs in severe congestive heart failure who are no longer responding to treatment efforts.
Symptoms of Congestive Heart Failure
Congestive heart failure can have different symptoms depending on what kind of heart disease is causing it and which side of the heart is affected.
Below are some clinical signs that may be associated with heart failure in dogs:
- Fainting or collapse (also known as syncope)
- Difficulty breathing, shortness of breath, and increased respiratory rate
- Exercise intolerance
- Persistent coughing
- Fatigue
- Pacing before bedtime and difficulty settling down
- Decreased appetite
- Swollen belly due to fluid accumulation
- Weight loss
- Change in gum or tongue color to a bluish-gray (a result of poor oxygen flow)
- Increased heart rate
- Heart murmur (abnormal heart sound) or arrhythmia (irregular heartbeat) may be heard when listening to a dog’s heart with a stethoscope.
- Crackling sounds may be heard when listening to a dog’s lungs with a stethoscope.
Some dogs may be diagnosed with a heart murmur and underlying heart disease before they are in heart failure. Others may already be in congestive heart failure when they are brought to an emergency vet.
Causes of Congestive Heart Failure
Several different types of heart disease can result in congestive heart failure. Heart disease may be congenital (present at birth) or acquired (develop later in life).
In dogs, the two most common causes of CHF are mitral valve disease and dilated cardiomyopathy.
Predisposing factors
Some dogs get heart disease and end up with congestive heart failure for reasons that are not always clear. However, some breeds of dogs are predisposed to developing certain heart conditions.
Age, weight, and nutrition may also play a role.
Mitral valve disease
Mitral valve disease, also known as mitral valve insufficiency or degenerative mitral valve disease, is the most common cause of congestive heart failure in dogs, accounting for approximately 80% of cases.
The mitral valve is located between the left atrium and ventricle and functions to keep blood flowing within the heart in the correct direction.
Mitral valve disease occurs when the mitral valve wears out or becomes leaky, allowing blood to flow back in the wrong direction.
Over time, this can lead to increased pressure in the left side of the heart and a backup of fluid into the lungs (congestive heart failure).
Mitral valve disease is most commonly seen in small breeds over the age of five, such as:
- Miniature Poodles
- Cocker Spaniels
- Cavalier King Charles Spaniels.
Dilated cardiomyopathy
Dilated cardiomyopathy results in weakening of the heart muscles, thus causing the heart to pump less effectively. As the diseprogresses,sses the heart chambers enlarge and the heart valves may leak, eventually leading to signs of congestive heart failure. Middle-aged large and giant breeds, such as Doberman Pinschers, Great Danes, and Boxers are predisposed.
Other causes
Other causes of heart disease, such as heartworms, patent ductus arteriosus, abnormal heart rhythms (arrhythmias), atrial or ventricular septal defects, infections, and cancer, can also lead to congestive heart failure.
Dogs generally do not have heart attacks like people do; however, sudden death is a possible result of many different types of heart disease.
How is Congestive Heart Failure Diagnosed?
There are several diagnostic tests that your vet will use to evaluate your dog’s heart.
They will begin by getting a history from you and performing a nose-to-tail physical examination. Depending on your vet’s experience and interest in cardiology, it is likely that you will be referred to a veterinary cardiologist for some or all of these tests.
While it may seem like a lot and can certainly become expensive, these tests will help determine the underlying cause of your dog’s heart failure and the best treatment options.
Auscultation
Using a stethoscope will allow your vet to listen closely to your pet’s heart and lungs. The location and intensity of a heart murmur can provide information about the underlying heart disease.
They will also make note of respiratory and heart rate, and feel your dog’s pulses.
Chest X-Rays
Radiographs are a good starting point to help visualize the size and shape of the heart and look for evidence of fluid build-up in the lungs, which could be a sign of heart failure.
Echocardiogram (Ultrasound)
An ultrasound of the heart allows a vet to see how effectively the heart is pumping and highlight areas with leaks or turbulent blood flow.
This test can be very helpful in figuring out what’s going on and can give accurate measurements of how well the heart is working.
Electrocardiogram (ECG)
A test to measure the electrical activity within the heart and evaluate heart rate and rhythm.
Blood Tests & Urinalysis
Bloodwork and urinalysis are important ways to evaluate overall systemic health and major organ function and look for markers that may be associated with heart disease. A heartworm test may also be conducted to identify any parasites.
How is Congestive Heart Failure Treated?
There is no cure for congestive heart failure. However, many dogs respond well to medication and lifestyle changes.
Dogs with CHF will need treatment and frequent monitoring for the rest of their lives. The goals of treatment are to:
- Decrease fluid congestion
- Maximize the amount of blood being pumped out to the body
- Improve clinical signs
Dogs with congestive heart failure might need to stay in the hospital for extra oxygen therapy in an oxygen cage, diagnostic tests, intensive treatments, and close monitoring.
Medications
There are multiple medications that may be used to treat dogs with congestive heart failure, depending on:
- The underlying heart disease
- Where the fluid has accumulated
- Clinical signs
- Severity of the disease
Multiple medications are often used together. Some of the most commonly used drugs include:
Diuretics
Diuretics such as furosemide promote thepromote excretion of excess fluid.
ACE Inhibitors
Angiotensin-converting enzyme (ACE) inhibitors like enalapril and benazepril lower blood pressure and relieve stress on the heart
Positive Inotrope
Positive inotropes such as Pimobendan help the heart pump stronger and more effectively.
Other Medications
Other medications, such as cough suppressants, may be used to help manage clinical signs.
Abdominocentesis
In addition to medication, patients with right-sided congestive heart failure may need to have fluid from their abdomen drained with a needle. This procedure, known as abdominocentesis, may be done every couple weeks to help make these dogs more comfortable.
It is also important to know which medications to avoid. Beta-blockers, for example, should not be used in patients with acute CHF.
Surgery
In some cases, surgery may be possible to correct an underlying defect in the heart.
For example, surgery to close a hole in the heart (called an atrial or ventricular septal defect) or an abnormal blood vessel (like a patent ductus arteriosus) may be beneficial.
Valve replacements are not commonly performed in dogs. For example, closing a hole in the heart (called an atrial or ventricular septal defect) or an abnormal blood vessel (like a patent ductus arteriosus).
Lifestyle
The following are some examples where a healthy lifestyle can benefit a dog with CHF.
Nutrition
There are prescription veterinary diets available for dogs with heart disease. In general, these dogs should be eating a low-sodium diet to help prevent fluid buildup.
Weight Maintenance
It is also important to keep your dog at a healthy weight.
Supplements
Certain supplements may be beneficial. These may include antioxidants like vitamin E and coenzyme Q10 and amino acids such as taurine and carnitine. Discuss the benefits of supplementation with a veterinarian.
In some cases, nutrition can actually play a role in preventing heart problems. Recently, a correlation has been found between feeding grain-free dog food and the development of dilated cardiomyopathy.
Therefore, it is best to avoid boutique or grain-free diets.
Exercise – Can you walk a dog with heart disease?
Many dogs love physical activity; however, intense exercise can worsen heart failure.
Gentle walks while monitoring your dog for signs of fatigue are still recommended. You and your dog should still be able to enjoy activities without placing too much stress on their heart.
Monitoring
Your vet will discuss what type of monitoring is recommended for your dog. This will include things that you can watch for at home as well as frequent rechecks with your vet.
One way to monitor left-sided congestive heart failure is to track respiratory rate, or how many times your dog breathes in/out per minute. In a sleeping or resting dog, the respiratory rate should be less than 30 breaths per minute. If it is higher than this, you should alert your vet.
Dogs on heart medications should have their blood work monitored to make sure that the medications are not affecting their kidneys or other organs.
Lastly, repeating chest x-rays and/or an echocardiogram routinely can help provide additional information about theabout progression of disease, especially if a pet parent is concerned about an increase in clinical signs.
What is the Prognosis and Life Expectancy for Dogs With Congestive Heart Failure?
In many cases, the prognosis depends on the underlying disease and stage of heart failure.
Dogs may do very well with heart disease for many years; however, once they have been diagnosed with congestive heart failure, their survival time is generally less than two years.
The average survival time for dogs with congestive heart failure due to mitral valve disease is nine months.
A dog’s life expectancy may also depend on things like its age and whether or not it has any underlying disease. With a proper treatment plan, most dogs are able to maintain a good quality of life for this time.
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Summary
While heart disease cannot be avoided in many cases, it is critical to feed a well-balanced diet, keep your pup at an ideal body weight, and keep up with routine heartworm prevention.
In many cases, heart disease cannot be prevented. However, it is important to feed a well-balanced diet, keep your pup at an ideal body weight, and stay up to date on routine heartworm prevention.
If you have any questions or concerns about your dog’s heart, be sure to bring them up with your vet.