Heart disease in dogs is managed through a combination of medications, lifestyle changes, and close monitoring at home. The specific treatment depends on how far the disease has progressed, but most dogs with heart disease can live comfortably for months or years with the right plan. The most common form is a degenerative condition affecting the mitral valve, though dilated cardiomyopathy and other types also occur. Here’s what treatment looks like at each stage and what you can do to help your dog.
How Vets Determine the Right Treatment Stage
Veterinary cardiologists classify heart disease into stages (A through D), and treatment decisions hinge on which stage your dog is in. Stage A simply means your dog is a breed at higher risk but has no detectable disease yet. No treatment is needed. Stage B is where things start to matter: your dog has a heart murmur or structural changes, but no symptoms. Stage B is split into two groups. In B1, the heart hasn’t enlarged enough to require medication. In B2, imaging shows the heart chambers have stretched and enlarged from the extra workload, and that’s the point where medication should begin, even though your dog still seems fine.
Stages C and D are where symptoms appear. Stage C means your dog is in or has experienced congestive heart failure, with fluid backing up into the lungs. Stage D means heart failure that no longer responds well to standard doses of medication. Your vet will use chest X-rays, echocardiograms (ultrasound of the heart), and sometimes blood tests to determine the stage. One useful blood marker measures a protein released when the heart is under stress. Values below 500 pmol/L generally rule out significant heart disease, while values above 1,725 pmol/L strongly suggest congestive heart failure is present.
Medications That Strengthen the Heart
The cornerstone drug for most dogs with heart disease is pimobendan, a medication that does two things at once. It helps the heart muscle contract more forcefully by making the muscle fibers more responsive to calcium signals inside each cell. At the same time, it relaxes blood vessels, which reduces the workload on the heart by making it easier to pump blood forward. This dual action is why pimobendan is typically the first medication started when a dog reaches stage B2, before any symptoms have appeared. Clinical trials have shown it delays the onset of heart failure by a significant margin when started early.
Your dog will take pimobendan twice daily on an empty stomach, usually about an hour before meals. It’s generally well tolerated, and many owners notice their dog’s energy level and appetite improve within the first week or two of starting it.
Managing Fluid Buildup
Once a dog enters congestive heart failure (stage C), fluid accumulates in or around the lungs because the heart can no longer pump efficiently. This is what causes the heavy, rapid breathing that’s often the first visible sign of trouble. Diuretics, which help the kidneys flush out excess fluid, become essential at this point.
Furosemide is the most commonly prescribed diuretic. Your vet will start at a low dose and adjust based on your dog’s breathing and comfort. For dogs whose heart failure becomes harder to control over time, a stronger alternative called torsemide may be used. Torsemide is roughly 10 times more potent than furosemide at low doses and up to 20 times more potent at higher doses. It also lasts longer in the body, which can provide more consistent relief. Vets typically reserve torsemide for cases where furosemide alone is no longer keeping fluid at bay.
Because diuretics increase urination, your dog will need more frequent access to water and outdoor breaks. Kidney values should be monitored regularly through blood work, since the kidneys are doing extra work to clear that fluid.
Reducing Strain on the Heart
ACE inhibitors are another standard part of the treatment plan, usually added at stage C alongside diuretics and pimobendan. These medications work by blocking a hormone pathway that constricts blood vessels and causes the body to retain salt and water. By shutting that pathway down, ACE inhibitors lower blood pressure, reduce the volume of fluid the heart has to handle, and improve blood flow to the rest of the body. Many owners notice their dog tolerates exercise better after starting one.
The most common side effects are related to blood pressure dropping too low, especially when combined with a diuretic. Signs to watch for include unusual tiredness, wobbliness, or loss of appetite. Kidney function needs periodic monitoring, particularly in older dogs or those already on multiple heart medications. Dogs with pre-existing kidney problems or dehydration are at higher risk for side effects, so your vet may start with a lower dose and increase gradually.
Surgical Options for Select Cases
For dogs with severe mitral valve disease, surgical repair is an option, though it’s only available at a handful of specialized centers worldwide and comes with a high price tag. Open-heart mitral valve repair has been performed successfully for years, primarily in Japan and a few other locations.
A newer, less invasive approach called transcatheter edge-to-edge repair uses a small clip device threaded through the blood vessels to grasp and stabilize the leaking valve leaflets, avoiding the need for open-heart surgery. In a clinical feasibility study of 50 dogs, the procedure was successfully completed in 92% of cases, and 96% of dogs survived to hospital discharge. Device-related complications occurred in about 6% of implanted clips, including occasional detachment from the valve leaflet. This technology is still limited in availability but represents a growing option for dogs who aren’t responding well to medications alone.
Monitoring Your Dog at Home
One of the most valuable things you can do is count your dog’s resting breathing rate. This is the single best early warning sign that heart failure is worsening or that medications need adjusting. While your dog is sleeping or resting calmly, count the number of breaths (one inhale plus one exhale equals one breath) over 30 seconds and multiply by two. A normal resting rate is usually under 30 breaths per minute.
If the rate consistently rises above 35 breaths per minute, especially with noticeable belly movement during breathing, that’s a sign fluid may be building up in the lungs again. The cardiology service at Tufts University advises that rates above 35 to 40 breaths per minute at rest warrant an extra dose of diuretic and a call to your vet. Tracking this number daily in a notebook or phone app helps you and your vet spot trends before they become emergencies.
Other signs to watch for include new or worsening cough (especially at night or when lying down), reluctance to eat, restlessness or inability to settle, and pale or bluish gums.
Exercise and Daily Activity
Dogs with heart disease don’t need to become couch potatoes, but the intensity and type of activity matters. Short, gentle walks are well tolerated by most dogs with mild to moderate disease. The key is letting your dog set the pace. If your dog normally walks ahead of you pulling the leash but starts falling back to walk beside you, that’s a signal they’ve hit their limit. If they sit down and refuse to continue, the walk was clearly too much.
Once a dog has been diagnosed with congestive heart failure, high-energy activities you initiate, like ball chasing, swimming, and running alongside other dogs, should be eliminated. These repetitive, exhausting efforts can worsen heart failure or trigger dangerous irregular heart rhythms. Let your dog choose their own activity level, and keep walks short and unhurried. On hot or humid days, scale back even further, since heat makes the heart work harder.
Diet and Weight Management
Keeping your dog at a healthy weight is one of the simplest and most impactful things you can do. Extra body weight forces the heart to pump harder with every beat. If your dog is overweight, work with your vet on a gradual weight loss plan. On the other hand, dogs in advanced heart failure sometimes lose muscle mass and body condition. If your dog is losing weight despite eating, your vet may recommend a higher-calorie diet or appetite-stimulating medication.
Moderate sodium restriction is commonly recommended for dogs in heart failure, since excess salt encourages fluid retention. This doesn’t mean you need a prescription diet in every case, but it does mean cutting out high-salt treats like deli meat, cheese, and many commercial dog treats. Your vet or a veterinary nutritionist can help you find the right balance for your dog’s stage of disease. Omega-3 fatty acids from fish oil are sometimes recommended for their anti-inflammatory properties, though the evidence for specific dosing in cardiac patients is still limited.
What Long-Term Management Looks Like
Treating heart disease in dogs is not a one-time fix. It’s an ongoing process of medication adjustments, regular vet visits, and daily observation. Most dogs with well-managed stage C heart failure live 6 to 18 months after diagnosis, though some do considerably better. Dogs started on medication at stage B2 often go a year or more before developing any symptoms at all.
Expect vet visits every 3 to 6 months for recheck exams, X-rays, and blood work. Medication doses will change over time as the disease progresses. Some dogs end up on four or five medications simultaneously. Keeping a consistent daily routine, giving medications on schedule, and tracking that resting breathing rate are the three most important things you can do to give your dog the longest, most comfortable life possible.