How do dogs develop congestive heart failure?

Left-sided heart failure is the most common cause of congestive heart failure in dogs. This is typically due to mitral valve disease, dilated cardiomyopathy, hypertrophic cardiomyopathy, and congenital heart defects like a patent ductus arteriosus. These heart diseases cause the heart to be unable to pump blood efficiently to the rest of the body. They may also raise the blood pressure in the veins causing fluid to leak out into other tissues or body cavities.

Congestive heart failure (CHF) may also be a hereditary condition in dogs. Read below for a list of the most common causes of canine CHF.

• Chronic valve disease - This can occur when the heart valves degenerate and eventually fail to function properly. This can lead to an increased heart load and eventually CHF.
• Dilated cardiomyopathy (DCM) - The condition is a frequent cause of CHF in certain breeds of dogs. Dilated cardiomyopathy is characterized by the enlargement of the heart that causes weakening and thinning of the heart’s muscular walls. When this happens, the heart is unable to pump adequate amounts of blood throughout the body.
• Mitral valve insufficiency - This can happen when the mitral valve between the heart’s left atrium and left ventricle, becomes “leaky”.
• Defects in the walls of the heart
• Abnormalities in heart rhythm (arrhythmias)
• Fluid in the pericardium (the sac that surrounds the heart)
• Increased blood pressure (hypertension)
• Endocarditis (inflammation of the endocardium, which is the heart’s inner lining and the valves)
• Tumors on or around the heart
• Pregnancy

When the ability of the heart to efficiently pump blood is affected, fluid may back up into the lungs and affected dogs experience breathing difficulties. There are instances when the fluid goes into the abdomen and gives the dog a pot-bellied appearance.

Is my dog at risk for congestive heart failure?

Several factors can increase a dog’s risk of congestive heart failure. These include:

Age - The incidence of CHF is higher in middle-aged to older dogs. Chronic valve disease (CVD) is the most common cause of congestive heart failure in dogs and affects more than 60% of senior dogs.

Size - Large dog breeds have higher risks for dilated cardiomyopathy, which is a leading cause of heart failure in these breeds. Some of the most common breeds affected by CHF are Labrador Retrievers, Golden Retrievers, and Doberman Pinschers.

Breed - Mitral valve degeneration (MVD) is a common cause of heart failure in small dog breeds. However, certain small breeds, such as the Toy Poodle, Shih Tzu, and Chihuahua have higher risks of being affected. Among the small dog breeds, it’s the Cavalier King Charles Spaniel that is most at risk for MVD.

Boxers are also prone to hereditary conditions affecting the heart (Boxer cardiomyopathy) that can lead to heart failure.

Heartworm disease - Untreated heartworm infections can increase a dog’s risk for CHF. As the number of adult heartworms increases, they can clog the heart and its major blood vessels. The worms can also interfere with the actions/functions of the heart valves.

Heart murmurs - When a defective heart valve leaks blood back into one of the heart’s chambers, it can cause a heart murmur, a condition that is usually an incidental finding during a routine medical exam. Most heart murmurs don’t cause any problems, but they can worsen with time, and can eventually lead to heart failure.

Diet - Nutrition-related factors, such as obesity, certain nutritional deficiencies, and a high-salt diet, can increase a dog’s risk of developing heart problems.

When your dog is overweight or obese, his heart will need to work harder so adequate blood can be circulated throughout the body.

Specific nutritional deficiencies, such as a lack of taurine ( a type of amino acid), can increase a dog’s risk of heart enlargement.

Dental disease - When your dog has a gum or tooth infection, bacteria from the mouth can enter the blood circulation and reach major organs of the body, such as the heart, and cause serious bacterial infections. Scientific studies have been able to demonstrate a strong association between tooth and gum disease and heart valve inflammation.

What symptoms might I notice if my dog is in heart failure?

Dogs with left-sided heart failure often have:

• A heart murmur, which is often present before developing heart failure. A murmur does not mean your dog will develop heart failure!
• Rapid breathing
• Labored breathing (increased effort, often abdominal push when breathing)
• Coughing
• Exercise intolerance
• Rapid heart rate
• Abnormal heartbeats/arrhythmia
• Blue coloration to gums or tongue (cyanosis)
• Fainting
• Anorexia
• Lethargy
• Tissue swelling around the muzzle in severe cases

What tests might be needed to diagnose congestive heart failure?

A good physical exam and auscultation (listening) to the heart and lungs are the first step. Before additional and sometimes stressful tests, your vet may recommend a sedative to relax your dog and let them calm down. Supplemental oxygen may be given if your dog is showing signs of stress or respiratory distress.

Once your pup is relaxed and stable, chest radiographs (x-rays) are often the next step. This allows your vet to look at the size and shape of the heart and vessels in the lungs, along with looking for abnormal fluid in the lungs and chest. If there is a lot of fluid present, it can obscure the heart itself, so radiographs may need to be repeated once the fluid has been removed and to assess response to treatment.

An echocardiogram, or ultrasound of the heart, is another good test. This allows your vet or cardiologist to look inside the heart at the valves and vessels and measure how much blood the heart is pumping compared to normal.

If your dog has an abnormal heartbeat, an electrocardiogram (ECG) may be recommended to determine the type of arrhythmia so appropriate medications can be given to control that.

Finally, there is a blood test called NT-proBNP Assay. This test detects a certain peptide that is released when the heart wall muscles stretch too much. This is a good screening test for breeds of dogs that more commonly develop congestive heart failure such as King Charles Cavalier Spaniels, Boxers, and Doberman Pinschers.

How long can dogs live with congestive heart failure?

Early diagnosis of congestive heart failure in dogs is very crucial as it can increase the chances of better outcomes. Once congestive heart failure develops, the survival time of affected dogs is expected to be between 6 and 14 months. Some dogs, however, can live for nearly three years with the right treatment regimen.

What treatments are available for dogs with congestive heart failure?

During an acute congestive heart failure crisis, your vet will give your dog injections of various medications such as furosemide to help remove excess fluid from the body. They may also apply nitroglycerin ointment to help dilate the veins. Pimobendan is a pill that helps the heart contract better. Occasionally, dopamine or dobutamine are needed in severe cases. Sedatives or stress reducers are also often given to help your pup relax and breathe easier as the other medications start to take effect.

Long-term treatments to continue at home once your dog has been stabilized include:

• Furosemide or spironolactone pills given multiple times per day to reduce fluid overload
• Pimobendan to help the heart contract more efficiently
• Enalapril or benazepril to reduce blood pressure
• Appropriate medications to treat any arrhythmia that may be present
• Low sodium diet!

Caring for a Dog with Congestive Heart Failure

While there is no cure when congestive heart failure develops, proper care and management can help your pet live longer and have a better quality of life. The following measures are important in the management of your pet’s heart condition:

1. Closely monitor the following:

• Your pet’s food and water intake
• Behavior
• General activity
• Respiratory rate
• Heart rate

2. Keeping a record of these symptoms and activities will make it easier for your vet to evaluate your pet.

3. Be familiar with your pet’s medications. Make sure to ask your vet about the purpose and possible side effects of each medication. The correct dosage and administration are very important.

4. Don’t skip your pet’s check-ups. Your vet needs to monitor your pet’s condition and there may be a need to review and make adjustments to your pet’s medications. If you have any questions and/or concerns about your pet, it’s a good idea to write them down before your pet visits the veterinary hospital so you can discuss them with your vet. During your pet’s check-ups, your vet may perform specific tests to monitor your pet’s vital functions.

5. Your pet will benefit from a low salt diet because heart failure can increase the tendency to retain water and salt. Your vet may prescribe a special diet that is appropriate for your dog’s condition.

6. Your dog will benefit from regular mild to moderate exercise. Create opportunities where your dog can engage in activities that don’t cause excessive panting or weakness. If your dog appears tired or suddenly collapses during an activity, you should bring this to your vet’s attention immediately.

Additional Monitoring and Treatment

Once your dog is started on medications to help reduce the frequency of CHF episodes, they’ll need regular blood work and recheck exams to assess how their organs are tolerating the drugs and reduced heart function. Close monitoring of your dog’s electrolyte levels is also necessary, as furosemide can cause severe losses of potassium.

Monitoring your dog’s Resting Respiratory Rate is a critical part of good home care. When resting (laying down napping or relaxed), the heart rate should be below 30 breaths per minute. If your dog consistently has a resting respiratory rate over 40-50 breaths per minute, they need to go to the vet immediately for an exam, chest radiographs, and in-hospital treatments to get them out of heart failure.

Unfortunately, there is no cure for heart failure. The medications are to help reduce fluid overload and give your dog more quality time in between episodes of heart failure. As the heart continues to deteriorate, the medications will be less effective and the heart failure episodes will become more frequent. If you have any concerns about your dog’s quality of life, please discuss this with your vet or schedule a consult with us at FirstVet.

Read more:

Your Pet’s Heart: A Guide to Understanding Heart Health in Dogs and Cats

Lung Cancer in Dogs and Cats

Why is my dog panting?

Need to speak with a veterinarian regarding your dog’s heart or another condition?

Click here to schedule a video consult to speak to one of our vets. You can also download the FirstVet app from the Apple App Store and Google Play Stores.