The heart is one of the most vital organs in a dog’s body. It’s responsible for ensuring that blood, rich with oxygen and nutrients, is pumped to every cell. The organ plays a crucial role in regulating a dog’s bodily functions by circulating blood to deliver oxygen to muscles, organs, and tissues while removing waste products like carbon dioxide. The ability to pump blood efficiently is crucial, particularly in identifying signs of heart disease in dogs at an early stage.
What is Heart Disease in Dogs?
Heart disease in dogs is a condition that can affect dogs of all kinds. Just like humans, a dog’s heart is essential for pumping blood and delivering oxygen throughout their body, so when the heart isn’t working properly, it leads to a lot of heart problems that affect their well-being. The tricky part is that heart disease often develops slowly, and the signs of heart disease can be easy to miss at first.
Signs of Heart Disease in Dogs

Most heart diseases progress slowly, which makes them difficult to notice in the earliest stages. However, there are common signs of heart dysfunction that can be linked to the condition. Here are some of the common signs of heart disease in dogs.
Persistent Coughing
Persistent and prolonged coughing can be an early sign of heart disease in dogs. This can happen for multiple reasons. One common reason is that the heart becomes enlarged, affecting other organs with its new size.
Another could be that the heart loses its efficiency in pumping, which also disrupts the processes of other surrounding organs that rely on the heart. This is often seen in cases of congestive heart failure, where fluid buildup in the lungs causes a chronic cough.
Difficulty Breathing
Dogs with heart disease may experience shortness of breath and difficulty breathing even though they have not moved a lot. When your dog’s heart is having trouble, it may be unable to pump blood efficiently, leading to a buildup of fluids in the lungs. You’ll notice this when your dog starts to pant more frequently, even though it hasn’t done a lot of work.
Lethargy
Your dog may start to show signs of tiredness or lethargy as heart disease in dogs progresses. This is often due to reduced blood flow and oxygen supply to the muscles, causing your dog to tire quickly during walks, playtime, or even normal daily activities. If your dog is suddenly less interested in exercise or more reluctant to engage in physical activities, it could be a warning sign, especially in dogs with heart disease.
Weight Loss
Heart disease can affect a dog’s appetite. If your dog is eating less than usual or has become uninterested in food, it could be a sign of heart disease. Additionally, some dogs with heart disease may begin to lose weight despite eating normally, as the body works harder to function, leading to heart muscle fatigue and muscle loss.
Swollen Abdomen
If your dog has a heart problem, it will be unable to pump blood efficiently. The abdomen becomes swollen, a condition referred to as ascites. This occurs when the heart struggles to pump blood effectively, causing fluid buildup in the abdominal cavity, which is a hallmark of congestive heart failure.
Blue or Pale Gums
A dog’s gums should be pinkish in a normal sense. However, if they start turning pale or blue, this usually means that they are not getting enough oxygen. This poor circulation of oxygen can be attributed to a heart disease, including improper blood flow, as the heart may have difficulty pumping efficiently.
Fainting
Fainting can occur when the heart is unable to pump blood to the brain. This can happen during periods of excitement, physical exertion, or even when your dog stands up too quickly. If you notice your dog collapsing or fainting, contact your vet, as this could be among the signs of heart disease in dogs.
Common Types of Heart Disease in Dogs

For heart disease in dogs, there are two common types of heart conditions. These are congenital heart disease and acquired heart disease. Each has its own set of characteristics and challenges.
Congenital Heart Diseases in Dogs
Congenital heart diseases are conditions that dogs are born with, often due to genetic factors. These conditions can affect the heart’s structure or function from a young age.
Dogs with PDA may exhibit signs like coughing, difficulty breathing, lethargy, and poor growth. In most cases, PDA will be diagnosed when a continuous heart murmur is observed during checkups at the clinic.
Patent Ductus Arteriosus
Patent ductus arteriosus (PDA) 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.
Signs of Patent Ductus Arteriosus
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.
Treatment for Patent Ductus Arteriosus
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 valves between the right ventricle and pulmonary artery are narrowed. Because of this narrowing, issues such as congestive heart failure and death become a greater risk. Labrador Retrievers, Beagles, and Cavalier King Charles Spaniels are common victims of this disease.
Signs of Pulmonic Stenosis
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.
Treatment for Pulmonic Stenosis
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. Cavalier King Charles Spaniel, Boxers, and other large breeds are commonly affected.
Signs of Subaortic Stenosis
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.
Treatment for Subaortic Stenosis
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 a common type of heart disease in dogs, 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.
Signs of Mitral Valve Disease
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.
Treatment for Mitral Valve Disease
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. As always, if you notice symptoms, contact your vet promptly.
Dilated Cardiomyopathy
DCM is a heart condition wherein the heart muscle of a dog becomes weaker. When this happens, the heart will be less effective in pumping blood. The blood will stay congested, leading to an increase in pressure and causing the walls of the heart to stretch. Breeds such as Newfoundlands and Boxers are at a higher risk.
Signs of Dilated Cardiomyopathy
Dogs with heart disease like DCM may show signs of lethargy, decreased appetite, intolerance to exercise, and difficulty breathing. As the heart disease worsens, dogs might faint or collapse, especially during playtimes and exercise.
Treatment for Dilated Cardiomyopathy
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 super long and can live in a dog’s heart for several years. The worms live in the dog’s heart and pulmonary arteries, impairing its ability to pump blood properly.
Signs of Heartworm Disease
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.
Treatment for Heartworm Disease
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 prevents younger heartworms from developing. Supplementary medications such as steroids help reduce the inflammation present.
“Heart disease in dogs often goes unnoticed until it’s advanced. That’s why routine checkups and paying attention to subtle changes, like a persistent cough or decreased energy, are crucial. Early diagnosis gives us the best chance to manage the condition and improve your dog’s quality of life.”
- Dr. Soheyl Simaei
Conclusion
Heart disease in dogs can be super concerning, which is why it’s essential to understand the signs of heart disease so we can provide immediate vet care. While some symptoms include common signs of heart dysfunction, such as lethargy, weight loss, and coughing, it’s essential to note these for your next visit.
Contact your vet for proper diagnostic tests and early treatment. Recognizing the types of heart disease, including dilated cardiomyopathy, patent ductus arteriosus, and congestive heart failure, could make all the difference in keeping your furry friend’s heart muscle healthy and strong.
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