Common Types of Heart Disease in Dogs

There are two categories of heart disease in dogs: congenital and acquired.

Congenital Heart Disease

These are heart problems in dogs that they are born with. Congenital heart disease consists of structural deformities that affect the heart's function. 

Patent Ductus Arteriosus

Patent ductus arteriosus is a congenital heart disease in dogs where the blood vessel ductus arteriosus does not close after birth. This vessel normally allows blood to bypass the lungs in a fetus. 

However, it should close after birth so the blood can circulate through the lungs. If it remains open, blood will flow abnormally between the heart and lungs, putting strain on the heart muscle.

Dogs with PDA may exhibit common signs of heart disease, like coughing, difficulty breathing, lethargy, and poor growth. In most cases, PDA will be diagnosed when a continuous heart murmur is observed during diagnostic tests at the clinic.

PDA can cause irreversible damage to a dog’s heart, meaning that urgent treatment is essential. In most cases, our veterinary surgeons will manage the condition, as surgery is typically required.

Pulmonic Stenosis

Pulmonic stenosis refers to a congenital heart disease in dogs, wherein the valve between the right ventricle and pulmonary artery is narrowed. Because of this narrowing, issues such as congestive heart failure and death become a greater risk. 

Labrador Retrievers, Bulldogs, and Boxers are common victims of this disease.

Some common signs of pulmonic stenosis include difficulty breathing, fainting, exercise intolerance, and the buildup of fluid in the abdomen. In most cases, these symptoms can appear at any time during a dog’s life.

Balloon valvuloplasty is usually the preferred treatment for pulmonic stenosis as it is minimally invasive. The goal of this treatment option is to widen the valve and create proper blood flow.

Subaortic Stenosis

Subaortic stenosis occurs when there is a constriction below the aortic valve. This makes it difficult for the heart to pump blood effectively. Golden Retrievers, Rottweilers, and German Shepherds are some of the most commonly affected by this disease. 

Dogs with heart disease can be observed to be weaker and more exhausted, having more difficulty breathing. The signs can range from mild symptoms, such as fainting, to dire ones, such as death.

The treatment procedure will depend on the situation of your dog’s SAS. Usually, no treatment is needed for mild cases. If the SAS condition worsens as your dog grows, beta-blockers may be necessary to help reduce the heart's workload and control abnormal heart rhythms.

Acquired Heart Diseases in Dogs

Acquired types of heart disease develop later in life, often due to age, infections, or other health problems. These conditions are more common in older dogs or certain breeds.

Mitral Valve Disease

Mitral valve disease is one of the most common forms of heart disease in dogs, especially in smaller breeds like Chihuahuas and Dachshunds. In this disease, the mitral valve doesn’t function as it’s supposed to, which causes some blood to leak in the wrong direction.

The earliest signs of heart disease in dogs don’t usually appear until later in life. These symptoms include a persistent cough, difficulty breathing, exercise intolerance, and a decreased appetite.

MVD is managed with medications such as diuretics. These medicines help reduce fluid buildup and strain on the heart. Other medications improve heart muscle function and protect the kidneys. 

Dilated Cardiomyopathy

Dilated cardiomyopathy is a type of heart disease in which the heart muscle becomes weakened and stretched, making it harder for the heart to pump blood. Breeds such as Newfoundlands, Boxers, and Dobermans are at a higher risk.

Dogs with DCM may appear lethargic, have a reduced appetite, and develop an intolerance to exercise. As this heart problem worsens, dogs might faint during playtime. 

DCM is usually managed rather than cured. ACE inhibitors help the heart pump blood more easily. Diuretics help remove fluid buildup in the lungs, reducing strain on the heart muscle and improving your dog’s ability to breathe.

Heartworm Disease

Heartworm disease is another common type of heart disease in dogs, caused by Dirofilaria immitis, which is transmitted through the bite of infected mosquitoes. These heartworms are long and can live in a dog’s heart and pulmonary arteries for several years. 

Some of the earliest signs of heart disease due to heartworms include coughing, lethargy, and difficulty breathing. In severe cases, congestive heart failure, collapse, or even sudden death may occur.

Heartworm disease can be cured with injectable drugs that kill the heartworms. To help keep your dog free from these parasites, heartworm preventives will be administered. These medications prevent younger heartworms from developing. 

Supplementary medications such as steroids help reduce the inflammation present.

“Early diagnosis gives us the best chance to manage the condition and improve your dog’s quality of life.”

- Dr. Mafalda Sardinha

Final Thoughts 

Heart disease in dogs can be concerning, which is why it’s essential to understand the signs so we can provide immediate vet care. Knowing each sign can put us one step closer to helping your dog through this difficult time.