Maltese Heart Disease (MMVD): Stages, Early Signs, and What U.S. Vet Care Really Costs

Read enough veterinary cardiology material on small breeds and one pattern keeps repeating: the disease is almost never caught at the moment it starts. It's caught at the moment it becomes inconvenient. A Maltese coughs a few times after drinking water, tires out a block earlier than usual on walks, and the owner files it under "she's just getting older." Months later, the same dog is in an emergency room at 2 a.m. with fluid in her lungs, and the vet mentions that a heart murmur was actually noted in the chart two years earlier.

That gap between "a murmur was noted" and "we're now in crisis" is the entire subject of this article. Myxomatous mitral valve disease, usually shortened to MMVD, is the most common acquired heart condition in small-breed dogs in the U.S., and the Maltese sits squarely in the at-risk group. The good news buried inside that sentence is this: MMVD is slow. It gives you years of warning, if you know what you're looking at.

🚨 Real Talk: What Every Maltese Owner Needs to Know About Heart Disease

• A heart murmur is not a diagnosis, and it's not nothing either: Most owners hear "there's a slight murmur" at an annual visit, feel relieved that no medication was prescribed, and never follow up. A murmur only tells your vet that blood is moving abnormally. Whether the heart has started to enlarge — which is the actual decision point for treatment — can only be answered with imaging, usually an echocardiogram.
• The cough you're worried about may not be the heart at all: Owners tend to assume a honking, gagging cough means heart failure. In small breeds, research has associated coughing more with an enlarged left atrium and coexisting airway disease than with congestive heart failure itself. Maltese are also prone to tracheal collapse, which produces that same goose-honk sound. Two different problems, two different treatment plans, and guessing wrong wastes months.
• Pet insurance timing is the mistake owners regret most: In the U.S., once a murmur or any heart abnormality is documented in your dog's medical record, most insurers treat the entire condition as pre-existing and exclude it. There is no retroactive fix. If your Maltese is young and clean on exam, that window is open right now, and it closes permanently at the first noted murmur.

What MMVD Actually Is (In Plain English)

The mitral valve sits between the left atrium and the left ventricle, and its job is simple: keep blood moving forward and stop it from washing backward when the heart squeezes. In MMVD, the valve tissue slowly thickens and deforms — the word "myxomatous" refers to that degenerative change — until the leaflets no longer seal cleanly.

Every heartbeat then pushes a small amount of blood the wrong way. The heart compensates the way any overworked pump does: it stretches and enlarges to handle the extra volume. For a long stretch of time, that compensation works remarkably well, which is exactly why so many dogs look completely normal in the early stages. Trouble starts when pressure backs up far enough that fluid begins seeping into the lungs. That's congestive heart failure, and it's the point at which the disease stops being invisible.

Why small white breeds like the Maltese? The predisposition appears to be genetic and structural rather than a simple matter of aging or lifestyle. Research into the genetic basis of MMVD has focused heavily on the Cavalier King Charles Spaniel, where prevalence is highest, but Maltese have also been studied for inherited susceptibility. Practically speaking, this means you cannot feed or exercise the risk away. What you can change is how early you find it.

(Heads up: a murmur's loudness does not reliably tell you how advanced the disease is. Quiet murmurs can accompany significant enlargement, and loud murmurs can sit stable for years. Loudness is a starting point for investigation, not a severity score.)

The ACVIM Stages, and What You'd Actually Notice at Home

U.S. vets stage this disease using consensus guidelines from the American College of Veterinary Internal Medicine (ACVIM). Understanding the letters matters because the entire treatment decision hinges on one specific transition — from B1 to B2 — and that transition is completely silent at home.

Stage A (At Risk, No Disease)

What you'll notice: Nothing. Your Maltese is here by breed alone — predisposed, but with a structurally normal valve and no murmur.

Vet approach: Careful annual listening with a stethoscope. Ask your vet directly, "Did you hear a murmur today?" and ask that the answer be written in the record either way.

Stage B1 (Murmur Present, Heart Not Enlarged)

What you'll notice: Still nothing. Normal energy, normal breathing, normal appetite. This stage can last years.

Vet approach: Monitoring rather than medication. Guidelines do not support starting heart drugs here. The purpose of rechecks is to catch the moment B1 becomes B2.

Stage B2 (Heart Enlargement, Still No Symptoms)

What you'll notice: Often still nothing obvious. Some owners look back and recall slightly reduced stamina or heavier panting after play, but plenty of B2 dogs seem entirely fine.

Vet approach: This is the decision point. Enlargement is confirmed with objective measurements on echocardiogram and chest radiographs, not eyeballing. The EPIC clinical trial found that starting pimobendan in dogs with preclinical MMVD and cardiac enlargement significantly delayed the onset of heart failure compared with placebo, which is why this stage now drives treatment in U.S. practice.

Stage C (Congestive Heart Failure)

What you'll notice: Now it's visible. Faster breathing at rest or during sleep, coughing, reluctance to lie flat, restlessness at night, exercise intolerance, sometimes a distinctly anxious look on the dog's face while breathing.

Vet approach: Diuretics to pull fluid out of the lungs, plus pimobendan and typically an ACE inhibitor and spironolactone depending on the case. Acute cases are handled as emergencies with oxygen support. Many dogs stabilize well and go home on oral medication.

Stage D (Refractory Heart Failure)

What you'll notice: Signs return or persist despite medication that previously worked. Appetite loss and weakness are common.

Vet approach: Aggressive diuretic strategies balanced against kidney function, additional drug classes, and frank conversations about quality of life. This is the stage where a board-certified cardiologist adds the most value.

The uncomfortable takeaway from this list: the stage where treatment does the most good is a stage you cannot detect by watching your dog. That's not a reason to panic. It's a reason to keep the recheck appointment.

What This Actually Costs in the U.S.

Cost is the part most articles either skip or fabricate, so here's the honest version. There is no single national price for cardiac care in the U.S. Veterinary pricing varies enormously by region, by whether you're seeing a general practitioner or a specialty referral center, and by how sick the dog is when it walks in. Anyone quoting you one exact number is guessing.

What is publicly verifiable: several U.S. university teaching hospitals and private cardiology practices publish fee information, and those documents have listed an initial cardiology consultation including an echocardiogram in the range of roughly $450 to $600. Owners in high-cost metro areas commonly report quotes above that. Treat these as published examples for planning purposes, not a national average, and call your own referral center for a written estimate.

Rather than invented figures, here's what actually moves your bill:

Cost Driver	Why It Changes the Number	What to Ask Your Vet
GP vs. specialist	A general practice murmur workup with chest X-rays costs far less than a full cardiology consult with echocardiogram, but it also answers fewer questions.	"Can you stage this from radiographs, or do we need an echo to know if we're at B2?"
Imaging vs. bloodwork screening	An NT-proBNP blood test is cheaper than echocardiography and can help decide whether referral is warranted, though it does not replace imaging for staging.	"Would a proBNP test be a reasonable first step for us before referral?"
Number of medications	A Stage B2 dog on one drug costs meaningfully less per month than a Stage C dog on three or four. Generic and compounded options can lower cost substantially.	"Is a generic or compounded version appropriate here, and can you write a script I can fill elsewhere?"
Recheck frequency	Dogs on diuretics need periodic kidney and electrolyte monitoring. Stable dogs need less; recently adjusted dogs need more.	"What's our recheck interval while he's stable, and what would make you want to see him sooner?"
Emergency vs. planned care	An overnight ER stay with oxygen therapy is almost always the single largest expense in this disease's timeline, and it's the one most influenced by how early you caught things.	"If he crashes overnight, which ER should I go to, and can I get their estimate range in advance?"

One more piece of U.S.-specific advice that has nothing to do with medicine: insure before you have a reason to. Pet insurance is priced on risk the insurer hasn't seen yet. The day a murmur enters the chart, MMVD generally becomes a pre-existing condition and stops being insurable. If your Maltese is two years old with a clean cardiac exam, this is the cheapest, highest-leverage decision available to you, and it will never be this easy again.

Home Monitoring That Actually Changes Outcomes

If you do only one thing from this article, do this one.

Count your dog's sleeping respiratory rate. Wait until your Maltese is genuinely asleep — not dozing, not dreaming and twitching. Watch the chest and count one full breath as in-and-out. Count for 30 seconds and double it, or a full 60 seconds if you can. Do it a few times a week and write it down in your phone.

Veterinary cardiology resources from U.S. teaching hospitals generally describe a normal sleeping or resting rate as somewhere in the range of 15 to 30 breaths per minute in healthy dogs and in dogs with well-controlled heart disease. A rate that sits consistently above 30 without an obvious explanation is a reason to call your vet. Just as important, and often missed: a rising trend against your own dog's personal baseline matters more than the exact number. A dog who has always slept at 18 and is now steadily at 28 is telling you something, even though 28 is technically "in range." That is the whole reason to write the numbers down.

Beyond breathing counts, a few practical habits worth building:

Switch from a collar to a harness. This is not fussiness. Neck pressure on a small breed already predisposed to airway collapse can trigger coughing fits that are genuinely distressing. A well-fitted harness that spreads pressure across the chest is a five-minute fix.

Watch the salt in treats, not just the food. Guidelines around cardiac diets emphasize avoiding high-sodium treats and table food more than aggressively restricting sodium in early disease. Jerky, deli meat, cheese, and most human snacks are the real culprits. Ask your vet what level of restriction fits your dog's specific stage instead of assuming stricter is better.

Protect muscle and body condition. Dogs with advancing heart disease can lose weight and muscle mass, which worsens how they feel and function. Sudden appetite loss in a dog with known MMVD is worth a phone call, not a wait-and-see.

Ask about exercise by stage rather than assuming. For asymptomatic dogs, there's generally no need to turn your Maltese into a couch ornament. Restrictions on strenuous activity become more relevant once clinical signs appear. Sedentary living has its own costs, so get stage-specific guidance rather than guessing.

(Heads up: if you ever see rapid labored breathing with the elbows held out, a bluish or grey tongue, or your dog refusing to lie down at all, that's an emergency room situation tonight — not a "call in the morning" situation.)

Finding the Right Vet for This

Most Maltese with MMVD are managed capably by general practitioners, and that's fine. Referral to a board-certified veterinary cardiologist — a specialist credentialed through ACVIM in cardiology — becomes especially worthwhile in a few specific situations: when you need an objective answer about whether the heart has enlarged enough to start medication, when a cough's origin is genuinely unclear between heart and airway, when medications aren't holding the disease, or when you're weighing a major decision and want a second set of eyes.

ACVIM maintains a searchable directory of board-certified specialists by location, and many U.S. veterinary schools run cardiology services that see referral patients. If you live somewhere without a cardiologist nearby, ask your vet whether they use a telecardiology service, where echocardiograms and radiographs are reviewed remotely by a specialist. It's a common arrangement and often far more accessible than a four-hour drive.

FAQ: Maltese Heart Disease and MMVD

How long can a dog live with a heart murmur?
Potentially years, and in many cases the murmur never progresses to heart failure at all. Survival varies enormously depending on the stage, how the dog responds to treatment, and other health conditions, so any single number you read online is unlikely to describe your dog. The more useful question for your vet is not "how long" but "what stage are we at, and what would change the plan?"

Is my Maltese coughing because of her heart?
Maybe, but don't assume it. In small breeds, coughing has been associated more strongly with an enlarged left atrium and concurrent airway disease than with congestive heart failure itself, and Maltese are separately prone to tracheal collapse. Distinguishing these usually takes chest radiographs and sometimes an echocardiogram, which is exactly why a cough deserves an exam rather than a guess.

Should I start heart medication if my dog has no symptoms?
That depends entirely on whether the heart has enlarged. Current U.S. guidelines don't support treating a murmur alone without enlargement, but for dogs meeting Stage B2 criteria, evidence from the EPIC trial supports starting pimobendan before symptoms appear. This is genuinely a case where the imaging determines the answer, so it's a conversation to have with your vet using actual measurements rather than a general rule.

Bottom Line: Get the Echo Before You Need the Emergency Room

Here's what makes MMVD in a Maltese so frustrating and so manageable at the same time. It moves slowly enough that you get years of opportunity, and quietly enough that most owners spend those years unaware the clock is running. The dogs who do best are rarely the ones with the most dramatic interventions. They're the ones whose owners kept the recheck appointment while the dog still looked perfectly healthy, counted sleeping breaths on an ordinary Tuesday, and made the phone call two weeks earlier than they felt they needed to.

If your Maltese is young and healthy, ask at the next visit whether a murmur was heard, and get insurance in place while you still can. If a murmur has already been noted, find out whether the heart has enlarged, because that single piece of information is what separates watchful monitoring from active treatment. Neither of those steps requires your dog to be sick first. That's the entire point.

This article is for general informational purposes only and is not a substitute for professional veterinary advice. If you notice any signs of abnormal behavior or symptoms in your dog, please visit a licensed veterinarian for a proper diagnostic exam (X-ray, ultrasound, or bloodwork as needed).

Related Reads

• Maltese Tracheal Collapse Guide: Symptoms, Stages, and U.S. Vet Costs
• Maltipoo Complete Guide: Generations, Separation Anxiety, and Genetic Health Risks
• Pomeranian Luxating Patella: 4 Stages From "Skip-Hop" to Surgery

Sources

• American College of Veterinary Internal Medicine (ACVIM) — consensus guidelines for the diagnosis and treatment of myxomatous mitral valve disease in dogs, including stage definitions and stage-based treatment recommendations
• EPIC study (Effect of Pimobendan in Dogs with Preclinical Myxomatous Mitral Valve Disease), published in the Journal of Veterinary Internal Medicine — evidence supporting treatment at Stage B2
• U.S. veterinary teaching hospital cardiology patient education materials — home sleeping and resting respiratory rate monitoring guidance
• Peer-reviewed veterinary cardiology research on risk factors for coughing in dogs with MMVD — association with left atrial enlargement and airway disease rather than congestive heart failure alone
• Published fee information from U.S. university veterinary teaching hospitals and private veterinary cardiology practices — cited as examples of consultation and echocardiogram pricing, not national averages
• American Animal Hospital Association (AAHA) — senior care and hospital accreditation standards
• U.S. pet insurance educational resources — definitions of pre-existing conditions and their effect on cardiac coverage

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This article is for educational purposes only and is not a substitute for professional veterinary advice. Please read our Medical Disclaimer and Editorial Policy for more information.