Heart Disease in Dogs: Treating the Most Common Causes

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Our dogs have our hearts, so naturally, we want to do everything possible to protect theirs. Understanding the risks of heart disease in dogs, as well as the symptoms and treatment options, is a great place to start.

Here's what you need to know about the most common types of heart diseases in dogs, the symptoms to watch out for, and the treatments that are available. With this information, you can work closely with your veterinarian to protect your dog's heart health and quickly develop a treatment plan should it start to decline.

Common types of heart diseases

The first step in treating heart disease is determining what type a dog has. Some of the most common types of heart disease in dogs are detailed below.

Chronic degenerative valve disease

Chronic degenerative valve disease (CVD) causes the valves between the atrium and ventricle to thicken and leak blood into the upper chambers of the heart. It's the most common type of heart disease in dogs.

The most common symptom of CVD is a heart murmur. But as the disease progresses, dogs may show more serious symptoms such as:

• Labored breathing

• Restlessness

• Trouble exercising

• Coughing

CVD can cause pulmonary hypertension, a dangerous increase in blood pressure in the lungs.

Small breeds that face a high risk of CVD include:

• Cavalier King Charles spaniels

• Miniature poodles

• Dachshunds

• Cocker spaniels

Dilated cardiomyopathy

Dilated cardiomyopathy occurs when heart muscle cells, or myocytes, die off in large numbers or malfunction. When this happens, the heart muscle loses its ability to contract and pump blood normally, causing symptoms such as:

• Heart murmur

• Abnormal heart rhythms

• Difficulty breathing

• Coughing

• Decreased appetite

Large breeds like boxers, Great Danes, and Saint Bernards face a high risk of dilated cardiomyopathy. Other risk factors include having a history of viral infections, such as parvovirus, or a deficiency of the amino acid taurine in the diet.

Heartworm disease

Heartworm disease occurs when a certain type of parasitic worm enters a dog's body via mosquito bite. Tiny worms then travel to the right side of the heart, where they grow, causing inflammation and damaging the heart, lungs, and arteries.

Symptoms of heartworm disease include:

• Coughing

• Labored breathing

• Exercise intolerance

Blood clots

Blood clots are restrictions in blood flow that can form in any artery or vein in a dog's body. Blood clots can become infected. And, in rare cases, they can travel and become lodged in the aorta or lungs, restricting vital blood flow and oxygen supply to body tissue.

Symptoms of a blood clot include:

• Sudden breathing difficulties

• Bloody mucus or urine

• Abdominal pain

Congenital heart defects

Heart defects that are congenital - meaning they're present at birth - are often genetic. But they can also be caused by poor environmental conditions, infections, and nutritional deficiencies in the mother.

It's very rare that a congenital heart defect causes heart disease in dogs. But the defects most likely to lead to heart disease are:

• Patent ductus arteriosus, a defect that disrupts blood flow in the heart

• Pulmonic stenosis, which blocks blood flow from the right ventricle to the lungs

• Aortic stenosis, a narrowing of the aorta that interrupts blood flow out of the heart

Heart failure

Congestive heart failure (CHF) occurs when a dog's heart is no longer able to pump enough blood to fulfill the body's needs. This can affect either one or both chambers of the heart.

Dogs who have any of the disorders listed above typically develop CHF eventually. The disease can also be caused by high blood pressure.

Common symptoms of CHF in dogs include:

• Persistent coughing

• Labored breathing

• Tiring easily

• Pale or bluish gums, accompanied by a heart murmur

• Fluid buildup in the lungs and/or belly

Heart arrhythmias

Arrhythmias are abnormal heart rhythms that can cause a wide range of problems. The most common types of arrhythmias in dogs are:

• Ventricular arrhythmia: This abnormal rhythm is most often seen in boxers, German shepherds, and bulldogs. When it occurs in rapid succession, it can lead to decreased blood flow throughout the body.

• Atrial fibrillation: This rapid beating of the heart, most often seen in large breeds, is associated with an enlarged heart or poor heart function.

• Sick sinus syndrome: When the heart's sinus node fails to trigger contraction, the heart stops, causing fainting. This syndrome is seen in some small breeds, including miniature boxers, cocker spaniels, and dachshunds.

• Heart block: When the ventricles fail to contract, heart block occurs, causing weakness and sometimes collapsing.

• Myocarditis: This inflammation of the heart can cause ventricular arrhythmias or heart block.

Treatment options for dogs

There are several treatment options for heart disease in dogs. Picking the right one for your dog starts with a trip to your vet, who will choose the ideal treatment regimen based on your dog's specific disease and its cause, as well as their age and lifestyle.

Below, we discuss the various types of treatment.

Heart disease medications

In general, medications that treat heart disease in dogs are designed to relieve symptoms and delay progression to CHF. But some medications work better for certain types of heart disease than others.

If your dog has pulmonary hypertension, your vet may prescribe them sildenafil (Viagra, Revatio). This medication expands blood vessels and relaxes muscles in the lungs.

If your dog has heart disease related to blood clots, your vet will likely prescribe them medication to prevent future clots, since it's difficult to break up existing ones. Some options are:

• Clopidogrel (Plavix)

• Aspirin

• Heparin

• Warfarin

There are several medications that are effective at managing heart arrhythmias in dogs, including:

• Amiodarone, which reduces the frequency of abnormal heart rhythms

• Beta blockers such as atenolol and carvedilol, which slow heart rate, thus reducing abnormal rhythms

• Digoxin, which is effective at slowing the heart rate of dogs with atrial fibrillation and CHF

• Diltiazem, which blocks an electrical signal that causes abnormal heartbeat

• Mexiletine or sotalol, both of which can be prescribed to treat ventricular arrhythmias

Dogs with CVD or another heart condition that has progressed to CHF can be prescribed a wide range of medications, including:

• Diuretics, which remove excess fluid from the body, such as furosemide (Lasix, Salix), spironolactone, and torsemide

• Medications that improve the heart's ability to pump blood, such as pimobendan (Vetmedin) and sacubitril / valsartan (Entresto)

• Medications that reduce blood pressure, such as hydralazine

• Omega-3 fatty acid supplements

Dogs with heartworms are treated with melarsomine dihydrochloride (Immiticide, Diroban). Though, the best defense is to prevent heartworms from infecting your dog in the first place with one of the many preventative treatments on the market.

Pacemakers

If your dog has an abnormal heartbeat, you may have treatment options beyond medication. Veterinary cardiologists often implant pacemakers in dogs with abnormal heart rhythms.

Diet and lifestyle changes

Your veterinarian may recommend several lifestyle changes that can benefit your dog's heart health. For example, an exercise regimen tailored to your dog's age and abilities can help them maintain a healthy weight and blood pressure, as can a balanced diet.

Dental cleaning habits

Maintaining healthy teeth and gums is also important, because bacteria in your dog's mouth can also cause heart inflammation. Brushing your dog's teeth, using dental wipes, or using water additives are good strategies for controlling harmful bacteria.

Surgery

Some congenital heart defects can be surgically corrected before they lead to CHF. For example, pulmonic stenosis can be treated by inserting a balloon into the heart to widen the narrow valve.

Surgical options have traditionally been limited for dogs with CVD. Though, a new treatment may be on the horizon. A team of veterinarians and medical device makers recently developed a procedure for dogs called TEER (transcatheter edge-to-edge repair). This involves inserting a small clip into the heart through a small incision in the dog's chest. The clip helps the heart valve close more fully, restoring normal blood flow.

Diagnosing heart disease in dogs

If your vet suspects heart disease, they will use a stethoscope to listen to your dog's organs, including their heart, lungs, and stomach. Your vet will also check your dog's pulse and examine any areas of swelling.

Sometimes, veterinarians also use X-rays to detect CHF or an EKG to diagnose irregular heart rhythms. A cardiac ultrasound, or echocardiograph, can be useful for obtaining a complete picture of how the heart, including the valves, is functioning. And a blood test can be used to detect heartworm disease.

In some cases, genetic testing could help diagnose heart disease. Several genetic variants have been linked to dilated cardiomyopathy in dogs, for example. Identifying that a dog is genetically predisposed to heart disease ensures they get the best care.

How long can a dog live with heart disease?

Generally speaking, a dog's ability to live a high-quality life with heart disease depends on several factors, including their age, the severity of their disease, and how well they respond to treatment.

Dogs with the most common cardiac disease, CVD, often live for 5 years or more without developing symptoms. Once the disease progresses to CHF, they can live up to 2 years with the help of medications that reduce the severity of their symptoms.

Frequently asked questions

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