Heart Disease in Senior Dogs: The Signs Every Owner Needs to Know

You noticed it a few weeks ago. Your dog — who used to bound to the door when you came home — now walks over slowly. The evening walk that used to take thirty minutes now ends after ten because he wants to turn back. Sometimes you hear a cough in the night that was not there before.

You told yourself it was just age. Maybe it is. But something in you is not sure.

As a veterinarian, I want you to know that what you are noticing may be more important than you realise. Heart disease is one of the most common — and most silently progressive — conditions in senior dogs. The earlier it is caught, the more we can do. And the window between "subtle signs you might miss" and "serious heart failure" is often measured in months.

This guide covers everything you need to understand about heart disease in senior dogs — what it is, how to spot it early, what your vet will do, and how to give your dog the best possible quality of life after diagnosis.

How Common Is Heart Disease in Senior Dogs?

The numbers are significant. Approximately 35% of senior dogs have some form of heart disease — meaning if you have a dog over seven, there is more than a one in three chance they will be affected at some point in their senior years.

Certain breeds carry a much higher risk. Cavalier King Charles Spaniels have the highest predisposition of any breed — virtually all Cavaliers will develop mitral valve disease if they live long enough. Other commonly affected breeds include Dachshunds, Miniature and Toy Poodles, Chihuahuas, Cocker Spaniels, and Doberman Pinschers.

Large breeds tend to develop a different form of heart disease — dilated cardiomyopathy — which affects the heart muscle rather than the valves. Breeds at risk include Great Danes, Irish Wolfhounds, Boxers, and Dobermans.

But heart disease is not exclusive to these breeds. Any senior dog can develop it — which is why recognising the signs matters for every owner.

Types of Heart Disease in Senior Dogs

Mitral Valve Disease — The Most Common Form

Mitral valve disease (MVD) is by far the most common heart condition in dogs, accounting for around 75% of all canine heart disease cases. The mitral valve sits between the left atrium and left ventricle of the heart. Its job is to ensure blood flows in one direction only.

As dogs age, the mitral valve can thicken and degenerate — becoming floppy and leaky. Blood begins to flow backwards through the valve with each heartbeat — a process called regurgitation. This creates the characteristic heart murmur your vet detects with a stethoscope, and over time causes the heart chambers to enlarge as they work harder to compensate.

In its early stages, MVD causes no symptoms and dogs feel completely normal. Over months to years, it can progress to congestive heart failure — the point at which the heart can no longer compensate and fluid begins to accumulate in the lungs.

Dilated Cardiomyopathy

Dilated cardiomyopathy (DCM) affects the heart muscle itself rather than the valves. The muscle weakens and the heart chambers enlarge and thin — reducing the heart's ability to pump blood effectively. DCM tends to progress faster than MVD and can cause sudden collapse or death in some cases without prior warning signs.

DCM primarily affects large and giant breeds, though a link between grain-free diets and DCM in breeds not typically predisposed has been under investigation in recent years. If your large-breed senior dog is on a grain-free diet, discuss this with your vet.

Arrhythmias

Arrhythmias are abnormal heart rhythms that can occur independently or alongside structural heart disease. Some arrhythmias are benign, others can cause fainting, collapse, or sudden cardiac death. They are diagnosed through an ECG (electrocardiogram) and may require specific medication to manage.

Early Signs of Heart Disease in Senior Dogs

This is the critical section — because the early signs of heart disease are subtle and easily attributed to normal aging. Here is what to watch for:

A Persistent Cough — Especially at Night

A dry, soft cough that has been present for weeks — particularly one that is worse when your dog is lying down, sleeping, or resting — is one of the most important early signs of heart disease. It is caused by a slightly enlarged heart pressing on the airways, or by early fluid accumulation in the lungs.

This cough is different from a kennel cough or throat irritation. It is usually not productive, does not sound harsh, and does not go away. If your senior dog has had a cough for more than a week with no obvious cause, see your vet.

Reduced Exercise Tolerance

A dog who used to walk happily for thirty minutes but now wants to stop after ten. A dog who tires more quickly than before, lags behind on walks, or needs to rest frequently. These are signs the heart is not efficiently delivering oxygen to the muscles — one of the earliest functional consequences of heart disease.

The change is often gradual, which is why owners tend to attribute it to aging rather than disease. If you have noticed a meaningful change in your dog's stamina over the past few months, it deserves investigation.

Faster Breathing at Rest

One of the most valuable things you can do as a senior dog owner is monitor your dog's resting respiratory rate. Count the number of breaths your dog takes per minute while they are fully relaxed and sleeping — not panting, not post-exercise.

A normal resting respiratory rate in dogs is 15 to 30 breaths per minute. A rate consistently above 30 breaths per minute at rest suggests fluid may be beginning to accumulate in the lungs — a sign of early congestive heart failure. This is urgent and needs same-day veterinary attention.

Lethargy and Weakness

General tiredness, reduced enthusiasm, spending more time sleeping, and less interest in activities they previously enjoyed. When the heart cannot pump blood efficiently, every organ — including the brain — receives less oxygen. The result is a dog who seems older, flatter, and less present than they used to be.

Loss of Appetite and Weight Loss

As heart disease progresses, reduced blood flow to the digestive system affects appetite. Dogs may become pickier, eat less, or lose weight despite eating the same amount. In advanced cases, a condition called cardiac cachexia — severe muscle wasting related to heart failure — can develop rapidly.

Swollen Abdomen

A visibly distended, pot-bellied abdomen in a senior dog that has not gained weight is a serious sign. It indicates fluid accumulation in the abdomen — called ascites — which occurs when right-sided heart failure causes fluid to back up into the abdominal cavity. This needs urgent veterinary attention.

Fainting or Collapsing

Brief episodes of fainting, sudden collapse during exercise, or moments where your dog seems to lose consciousness and then recover quickly are serious warning signs of arrhythmia or severely reduced cardiac output. Any episode of fainting in a senior dog is a veterinary emergency.

Blue or Grey Gums

Healthy dog gums are pink and moist. Blue, grey, or white gums indicate that insufficient oxygen is reaching the tissues — a sign of advanced heart failure or acute cardiovascular crisis. This requires emergency veterinary care immediately.

What Will Your Vet Do?

If your vet suspects heart disease, here is what the diagnostic process typically involves:

Auscultation — Listening to the Heart

Your vet will listen carefully to your dog's heart with a stethoscope. A heart murmur — a whooshing sound caused by turbulent blood flow — is the most common finding in early MVD. Murmurs are graded on a scale of 1 to 6, where 1 is barely audible and 6 is audible without a stethoscope. The grade does not directly predict severity of disease but helps track progression over time.

Chest X-rays

X-rays allow your vet to assess heart size and shape, and critically — to check for fluid in the lungs. An enlarged heart on X-ray is a sign of disease progression. Fluid in the lungs (pulmonary oedema) confirms congestive heart failure has developed.

Echocardiogram — Ultrasound of the Heart

An echocardiogram is the gold standard for diagnosing and staging heart disease. It allows direct visualisation of the heart chambers, valves, and muscle — measuring their size and function in real time. It shows exactly how much the valve is leaking and how well the heart is compensating. This may be performed by your regular vet or referred to a veterinary cardiologist.

ECG

An electrocardiogram records the electrical activity of the heart and is used to detect arrhythmias. It may be recommended if your dog has episodes of fainting or if an irregular rhythm is detected during auscultation.

Blood and Urine Tests

Blood tests assess kidney function, liver health, and electrolyte balance — all of which are important before starting heart medications. A biomarker called NT-proBNP can be measured in the blood and indicates cardiac stress — useful for early detection and monitoring treatment response.

Treatment Options for Heart Disease in Senior Dogs

There is no cure for most forms of heart disease in dogs. The goal of treatment is to slow progression, manage symptoms, prevent congestive heart failure, and maintain the best possible quality of life.

Pimobendan

Pimobendan is currently the most important medication in canine heart disease management. It strengthens the heart's contractions and dilates blood vessels, reducing the workload on a failing heart. The landmark EPIC trial demonstrated that starting pimobendan before congestive heart failure develops — in dogs with enlarged hearts — significantly delays the onset of heart failure and extends survival time. Ask your vet whether your dog meets the criteria to start pimobendan.

ACE Inhibitors

Medications like enalapril and benazepril reduce blood pressure and the workload on the heart. They are commonly used alongside pimobendan in dogs with heart failure.

Diuretics

Frusemide (furosemide) is the primary diuretic used in congestive heart failure to remove excess fluid from the lungs and body. It is a life-changing medication for dogs in heart failure — often producing dramatic improvement in breathing within hours of the first dose.

Dietary Management

A moderate sodium restriction is generally recommended for dogs with congestive heart failure — but severe sodium restriction is no longer recommended as it can be counterproductive. Prescription cardiac diets are formulated appropriately. Maintaining a healthy body weight is important — both obesity and excessive weight loss worsen outcomes.

Monitoring at Home

Once heart disease is diagnosed, monitoring your dog's resting respiratory rate at home becomes one of the most valuable things you can do. Count breaths per minute during sleep, at the same time each day, and keep a log. A consistent rise above 30 breaths per minute is an early warning sign that fluid is accumulating — allowing intervention before a crisis develops.

How Long Can a Dog Live With Heart Disease?

Prognosis varies enormously depending on the type of heart disease, the stage at diagnosis, the breed, and how well the condition is managed.

Dogs with early-stage MVD diagnosed before congestive heart failure develops — and started on appropriate medication — can live comfortably for one to three years or more after diagnosis. Dogs diagnosed at the point of first congestive heart failure typically have a median survival of around one year with good medical management, though many live longer.

What consistently makes the biggest difference is early detection, consistent medication, and attentive monitoring at home.

A Final Word From Dr. Waleed

Heart disease is a condition where time genuinely matters. The dog caught with an early murmur who starts medication before heart failure develops has a meaningfully different future than the dog who comes in when they can barely breathe.

If your senior dog has not had their heart listened to in the past year — book a wellness check. It takes sixty seconds with a stethoscope to detect a murmur. That sixty seconds could give you years.

And if you have noticed any of the signs in this guide — the cough, the tiredness, the faster breathing at rest — please do not wait. You know your dog. That instinct that brought you here to read this matters. Trust it.

Frequently Asked Questions

My old dog has started coughing at night — could it be his heart?

Yes, a persistent cough in a senior dog — especially one that is worse at night or when lying down — is one of the classic early signs of heart disease. It is caused by an enlarged heart pressing on the airways or early fluid building up in the lungs. It is different from a regular cough — it tends to be soft, dry, and does not go away. Book a vet appointment this week and mention the cough specifically.

My dog gets tired much faster on walks than he used to — is that heart disease?

Reduced exercise tolerance is one of the earliest signs that a dog's heart is not delivering oxygen efficiently to the muscles. If your senior dog is tiring noticeably faster than a few months ago, stopping earlier on walks, or lagging behind — that change deserves a vet check. It is easy to attribute to normal aging, but it is often the first functional sign that something is changing with the heart.

What does a heart murmur in a dog actually mean?

A heart murmur is a sound your vet hears through the stethoscope — a whooshing or swishing caused by turbulent blood flow, usually from a leaky valve. Finding a murmur does not mean your dog is about to go into heart failure. Many dogs live for years with a murmur and no symptoms at all. What it means is that monitoring and possibly further testing are needed to track the disease and intervene at the right time.

How do I check my dog's breathing rate at home?

Wait until your dog is fully asleep and relaxed — not panting, not just rested from exercise. Count the number of times their chest rises in 60 seconds. That number is their resting respiratory rate. A normal rate is 15 to 30 breaths per minute. If you consistently count above 30 when they are sleeping, contact your vet the same day. This is one of the most useful things you can do to monitor heart disease at home.

My vet found a heart murmur — does my dog need medication now?

Not necessarily right away. The decision to start medication depends on the grade of the murmur, whether the heart has started to enlarge, and your dog's breed and overall condition. The EPIC trial showed that starting pimobendan before heart failure — but after the heart has enlarged — significantly delays progression. Your vet may recommend chest X-rays or an echocardiogram to assess whether your dog has reached that threshold.

Can a dog with heart disease still go for walks?

Yes, in most cases — but the type and intensity of exercise needs to be adjusted. Short, gentle leash walks are appropriate for dogs with early to moderate heart disease. Avoid strenuous activity, off-leash running, or anything that causes heavy panting or distress. In dogs with congestive heart failure, even gentle walks should be guided by how your dog responds and what your vet advises. Watch their breathing during and after exercise.

Have a Question for Dr. Waleed?

Worried about your senior dog's heart health or not sure what a recent diagnosis means? Send me your question on the Ask Dr. Waleed page. I read every message personally and will do my best to help you understand what comes next.

Related Posts You May Find Helpful

• Kidney Disease in Senior Dogs: What Every Owner Needs to Know
• How Much Exercise Does a Senior Dog Actually Need?