Heart Disease in Senior Dogs: The Cough, the Breathing Test, and What It Means

By Sarah Bennett · Last updated June 8, 2026 · 12 min read

Information, not diagnosis. We are not veterinarians. If your dog has blue, grey, or purple gums, is breathing hard with the mouth open and cannot settle, or collapses, that is an emergency. Go to a vet now.

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A soft cough that shows up at night. A dog who used to lead the walk and now stops halfway. More sleeping than usual. Any one of these in an older dog can be an early sign of heart disease, and the honest reason this page exists is that the signs are quiet and easy to write off as "just getting old." Here is the part worth holding onto: heart disease in senior dogs is common, it is usually slow, and when it is caught early it is one of the most manageable serious conditions an old dog can have. A heart murmur is a reason to start watching, not a reason to panic.

There are two things this article will give you that most do not. First, a cough in an older dog is not automatically the heart, and confusing the two can send you down the wrong path. Second, there is a single number you can track at home, for free, that is the best early-warning sign there is of heart trouble turning into heart failure. We will get to both.

Is My Old Dog's Cough a Sign of Heart Disease?

Maybe, but a cough has more than one common cause in a senior dog, and telling them apart changes everything. The three that overlap most are:

Heart disease (congestive heart failure). A failing heart lets fluid back up into the lungs, and the cough is usually soft and moist, often worse at night or after lying down, and it comes with faster breathing and tiring easily.
Tracheal collapse. The windpipe softens and flattens, classically in small and toy breeds, giving a dry, harsh "goose honk" cough that flares with excitement, exercise, heat, or a tug on the collar.
Laryngeal paralysis. The voice box stops opening fully, more often in older large breeds, giving a raspy breathing sound and a changed bark.

Here is the catch that trips people up: a small older dog can have both a collapsing trachea and heart disease at the same time, because the same toy breeds are prone to each. That is exactly why a cough in a senior dog is a vet visit, not a guess. A stethoscope, and often a chest X-ray, sorts out what is actually driving it.

The Most Common Heart Disease in Senior Dogs

By far the most common heart problem in older dogs is myxomatous mitral valve disease (MMVD), also called degenerative or chronic valve disease. The mitral valve, one of the heart's one-way doors, slowly thickens and stops sealing, so a little blood leaks backward with each beat. That leak is what your vet hears as a heart murmur, and it is usually the very first sign, found on a routine exam long before the dog feels unwell. MMVD is most common in small and toy breeds, such as Cavalier King Charles Spaniels, Chihuahuas, and many small mixes.

Large and giant breeds are more prone to a different problem, dilated cardiomyopathy (DCM), where the heart muscle itself weakens and stretches. It tends to be quieter in its early signs, which is one reason large-breed seniors benefit from a vet listening to the heart at every visit.

The reassuring thread through both: a murmur or an early diagnosis does not mean your dog is in heart failure. Many dogs live for years in the early stages with no treatment needed at all, just monitoring.

The Home Test That Matters Most: Resting Respiratory Rate

If you take one practical habit from this page, make it this one, because it is the best early-warning sign of heart failure you have, and it costs nothing.

When your dog is asleep or fully at rest, watch the chest rise and fall, count the breaths for 30 seconds, and double it. One breath is one in-and-out.

Under about 30 breaths per minute asleep or at rest is normal for nearly all dogs.
Consistently over 30, or a steady climb over several days, is one of the earliest signs that fluid is starting to back up into the lungs, often before any cough appears.

Write the number down a few times a week so you know your own dog's baseline. The trend matters more than any single count. A resting rate that is creeping up is the signal that gets a dog seen and treated before a crisis, and cardiologists rely on this exact number to catch worsening heart failure early. We started tracking it for Lucy, our 7-year-old Border Collie, not because she has heart disease, but because the habit is easiest to build before you need it.

Honestly, the hardest part of the hand-count is just keeping it up. Life gets busy, a week slips by, and the one habit that could catch trouble early goes quiet. That is where a wearable earns its place. We like Maven Pet for this: a small sensor that clips onto the collar she already wears and watches her resting respiratory rate and heart rate around the clock, then tells you when the trend starts to climb, including on the nights you are asleep and can't be counting. It does not diagnose anything, and it is not trying to. What it gives you is a second set of eyes on the number that matters, and a little less of the quiet worry that you might miss the moment it changes. The free 30-second count still works beautifully, and it costs nothing. But if you have ever lain awake wondering whether you would notice in time, that is exactly the weight a quiet monitor on her collar can lift. Our honest Maven Pet review lays out who it is worth it for and who should skip it. (Maven is an affiliate partner, so we may earn a commission if you subscribe, at no extra cost to you.)

See Maven's current plans and pricing →

Early Signs of Heart Failure in Senior Dogs

Heart disease becomes heart failure when the heart can no longer keep up and fluid backs up into the lungs or belly. The early signs are easy to miss because they look like aging:

A soft, moist cough, often worse at night or when lying down
Tiring on walks your dog used to manage, or stopping to rest
Breathing faster or harder at rest (the resting rate above)
Sleeping more, and seeming less interested in activity
Fainting or a sudden wobble (syncope), often after excitement or exertion
A swollen, rounded belly from fluid, in right-sided failure

None of these is proof of heart failure on its own, and their absence does not rule heart disease out. They are reasons to have your vet listen to the heart and, if needed, take a chest X-ray or an echocardiogram, which is the ultrasound that actually measures how the heart is working.

How Heart Disease in Senior Dogs Is Staged and Treated

Veterinary cardiologists stage MMVD in a way that is genuinely useful for owners to understand, because the stage decides what, if anything, to do.

Stage	What it means	Typical action
B1	A murmur, but a normal-sized heart	Monitor only; no treatment. Many dogs stay here for years
B2	A murmur with an enlarged heart, no symptoms yet	Early treatment pays off: pimobendan delayed heart failure by over a year in the EPIC study
C	Congestive heart failure has developed	A diuretic to clear fluid plus pimobendan; many dogs feel well again
D	Advanced failure no longer responding to standard treatment	Managed with a cardiologist's help

Stage B1: a murmur, but a normal-sized heart. No treatment, just monitoring. Many dogs stay here for years.
Stage B2: a murmur with an enlarged heart, but no symptoms yet. This is the stage where early treatment pays off. The drug pimobendan has been shown to delay the onset of congestive heart failure by over a year on average, in a large clinical trial known as the EPIC study. This is the single best argument for getting a murmur checked properly with imaging.
Stage C: the dog has developed congestive heart failure. Treated with a combination of medications, typically a diuretic to clear the fluid plus pimobendan, which lets many dogs feel well again.
Stage D: advanced failure that no longer responds easily to standard treatment, managed with the help of a cardiologist.

The point of the stages is hope with a plan. Heart disease is not one sudden event; it is a slope you can see coming and act on. A dog caught at stage B2 and started on the right medication can have that extra year or more before failure even begins.

When Heart Disease Is an Emergency

Most heart disease moves slowly, but fluid in the lungs can tip a dog over quickly. Go to a vet immediately for any of these:

Blue, grey, or purple gums or tongue (not enough oxygen)
Labored, open-mouth breathing at rest that will not settle
A resting breathing rate that is suddenly very high along with distress
Collapse or fainting that does not quickly resolve

If your dog is in obvious respiratory distress, keep them calm and cool and get to the nearest open clinic, because acute heart failure is treatable in an emergency setting, and minutes of fear and heat make it worse.

Frequently Asked Questions

Is my old dog's cough a sign of heart failure? It can be, but a cough in a senior dog is just as often tracheal collapse or another airway problem, and small older dogs can have both at once. A heart-failure cough is usually soft and moist and comes with faster breathing and tiring easily, while a tracheal-collapse cough is dry and honking and flares with excitement. Only a vet exam, often with a chest X-ray, can tell them apart, so a new cough is worth a visit.

What is a normal resting respiratory rate for a dog, and why does it matter? Under about 30 breaths per minute while asleep or fully at rest is normal for nearly all dogs. Count the chest rises for 30 seconds and double it. A resting rate that is consistently over 30, or steadily climbing, is one of the earliest signs that heart failure may be developing, often before a cough appears, which is why cardiologists treat it as a key home monitoring number.

How long can a dog live with congestive heart failure? It varies widely, but it is not the immediate end that many owners fear. With the right combination of medications, many dogs in heart failure feel well and live comfortably for months to a year or more, and some longer. Early treatment, careful monitoring of the resting breathing rate, and working closely with your vet make the biggest difference to both length and quality of that time.

What is the difference between a heart murmur and heart failure? A murmur is a sound, the noise of blood leaking through a valve that no longer seals, and it is often the first and only sign for years. Heart failure is when the heart can no longer keep up and fluid backs up into the lungs or belly. A dog can have a murmur for a long time without ever being in heart failure, which is why a murmur means monitor, not panic.

Can heart disease in dogs be treated? Yes. While the underlying valve or muscle change cannot be reversed, heart disease is one of the more manageable serious conditions in older dogs. In the enlarged-heart stage before symptoms, medication can delay heart failure by over a year on average. Once heart failure begins, diuretics and other heart medications let many dogs feel well again for a good stretch of time.

Sources

Keene BW, Atkins CE, Bonagura JD, et al. (2019). "ACVIM consensus guidelines for the diagnosis and treatment of myxomatous mitral valve disease in dogs." Journal of Veterinary Internal Medicine 33(3), disease staging (B1, B2, C, D) and treatment
Boswood A, et al., the EPIC study (2016), Journal of Veterinary Internal Medicine: pimobendan delays the onset of congestive heart failure in stage B2 MMVD
Cornell University College of Veterinary Medicine, Riney Canine Health Center: heart disease and tracheal collapse in dogs
Merck Veterinary Manual: Heart Failure in Dogs (signs, congestive heart failure, resting respiratory rate monitoring)

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About the authors

Senior Dog Daily is written by Sarah Bennett and Leo Bennett, a husband-and-wife team in the American Midwest, with their Border Collie Lucy as the reason it started. Neither of us is a veterinarian. We read the primary sources, including the ACVIM cardiology consensus guidelines and veterinary hospital references, and turn them into plain guides, with the claims traceable to the sources above. With heart disease in senior dogs, the kindest thing you can do is learn the quiet early signs, track the resting breathing rate, and get a murmur looked at properly, because this is one serious diagnosis where catching it early genuinely changes the story.