If your dog has been diagnosed with a heart murmur, the most important things to avoid are excess sodium in their diet, intense or uncontrolled exercise, certain pain medications, and neglecting early warning signs that the condition is progressing. A heart murmur itself isn’t a disease. It’s a sound caused by turbulent blood flow through the heart, and it can range from mild and harmless to a sign of serious valve disease. What you need to avoid depends heavily on how advanced the underlying heart condition is.
How Heart Murmur Stages Affect What You Avoid
Veterinary cardiologists classify heart disease into four stages, and understanding where your dog falls changes everything about what precautions matter. Stage A simply means your dog belongs to a breed at higher risk (like Cavalier King Charles Spaniels) but has no detectable heart changes yet. Stage B means structural changes are present, such as a leaky valve, but your dog has never shown symptoms of heart failure. Stage B is further split: B1 means the heart hasn’t started enlarging, while B2 means it has enlarged enough that medication should begin even before symptoms appear.
Stage C means your dog has had or currently has symptoms of heart failure, like coughing, rapid breathing, or exercise intolerance. Stage D is end-stage disease where standard treatments are no longer enough. Dogs in stages A and B1 need fewer restrictions, while dogs in stages B2 through D need progressively more careful management of diet, activity, and medications.
Sodium and Salty Foods
Salt is the single biggest dietary concern. Sodium causes the body to retain fluid, and for a dog whose heart is already struggling to pump efficiently, extra fluid can push them toward congestive heart failure. The restriction gets tighter as the disease progresses. For dogs in early stages, veterinary nutritionists recommend keeping sodium below 100 milligrams per 100 calories of food. For moderate disease, that drops to below 80 milligrams per 100 calories. Advanced stages may require even stricter limits.
In practical terms, this means cutting out the human foods many owners casually share with their dogs. Deli meats, cheese, bacon, hot dogs, canned soups, bread, pizza crust, and potato chips are all high in sodium. Even foods that don’t taste particularly salty to you can contain surprising amounts. Processed dog treats can also be sodium-heavy, so check labels carefully or switch to low-sodium options your vet recommends. The general rule from the American College of Veterinary Internal Medicine is to avoid any processed or salted foods entirely.
Exercise That’s Too Intense
Exercise isn’t off the table for most dogs with heart murmurs, but the wrong kind can be dangerous. The key distinction is between controlled, moderate activity and high-intensity bursts. For dogs with stable heart failure, research supports light walks of 20 to 30 minutes, two to three times per week, as both safe and beneficial. Aerobic activity at a moderate level actually helps the cardiovascular system adapt.
What you should avoid is letting your dog sprint after squirrels, play rough at the dog park for extended periods, or push through obvious fatigue. Dogs with heart disease don’t always self-regulate well. If your dog is panting heavily, lagging behind, or seems reluctant to continue, stop immediately. For dogs actively experiencing congestion or fluid in the lungs, even light exercise is off limits until they’re stabilized on medication. When in doubt, less intensity is always the safer choice.
Anti-Inflammatory Pain Medications
Nonsteroidal anti-inflammatory drugs, the class that includes common pain relievers like carprofen and meloxicam, are a recognized cause of diuretic resistance in dogs with heart disease. Many dogs with heart murmurs take diuretics to prevent fluid buildup, and these pain medications can make the diuretics stop working effectively. This can trigger a dangerous fluid overload.
If your dog has arthritis or another painful condition alongside their heart murmur, don’t reach for leftover pain medications without checking with your vet first. There are alternative pain management strategies that don’t carry the same cardiac risks. This also applies to any over-the-counter human painkillers you might consider giving your dog, which are dangerous for multiple reasons beyond heart interactions.
Grain-Free Diets Without Veterinary Guidance
The FDA investigated a potential link between certain grain-free diets and dilated cardiomyopathy (a type of heart disease where the heart muscle weakens and enlarges) in dogs. While the agency hasn’t established a definitive causal relationship, calling it “a complex scientific issue that may involve multiple factors,” the investigation prompted enough concern that it’s worth paying attention to. If your dog already has a heart murmur, switching to or continuing a grain-free diet without discussing it with your vet adds an unnecessary variable. The investigation remains open, with the FDA noting they’ll provide updates when meaningful new scientific information emerges.
Equally important: avoid low-protein diets designed for kidney disease unless your dog genuinely has severe concurrent kidney failure. Dogs with heart disease need adequate protein to maintain muscle mass, including heart muscle. Restricting protein without a clear medical reason can worsen cardiac outcomes.
Ignoring Dental Disease
This one surprises many owners. Periodontal disease, the buildup of bacteria along the gumline, has a significant association with cardiovascular conditions in dogs, including endocarditis (infection of the heart valves) and cardiomyopathy. The mechanism is chronic inflammation: bacteria from infected gums enter the bloodstream and can settle on already-damaged heart valves, making a murmur worse or triggering new complications.
Avoiding dental care is, paradoxically, one of the riskier things you can do. Regular teeth cleaning, dental chews approved by your vet, and monitoring for signs of gum disease (bad breath, red gums, difficulty eating) all matter more when your dog’s heart is already compromised.
Anesthesia Without Cardiac Workup
If your dog needs surgery or a dental cleaning under anesthesia, skipping a pre-surgical cardiac evaluation is a serious risk. General anesthesia can depress heart function, cause rapid heart rate changes, and alter blood pressure in ways that a healthy heart compensates for but a compromised heart may not. Dogs with heart disease also have a much narrower tolerance for IV fluids during surgery. Too much fluid can cause pulmonary edema (fluid in the lungs), and too little can damage the kidneys.
Before any procedure requiring anesthesia, your dog should have chest X-rays and an echocardiogram at minimum. These identify how severe the valve disease is, what complications to expect, and how the anesthesia plan should be adjusted. This doesn’t mean your dog can never go under anesthesia. It means the veterinary team needs to know exactly what they’re working with so they can keep the heart rate controlled and fluid volumes precise.
Missing the Early Signs of Heart Failure
Perhaps the most important thing to avoid is complacency about monitoring. A heart murmur can stay stable for years, or it can progress to heart failure over months. The single most reliable early warning sign you can track at home is your dog’s sleeping breathing rate. Count the number of breaths your dog takes in 60 seconds while they’re asleep (one rise and fall of the chest equals one breath). A consistent rate above 30 breaths per minute is abnormal and suggests fluid may be accumulating in or around the lungs.
Get in the habit of checking this a few times per week and writing it down. Knowing your dog’s normal baseline (most healthy dogs breathe 15 to 25 times per minute while sleeping) lets you spot a trend upward before it becomes an emergency. Other signs to watch for include new or worsening cough, reluctance to exercise, restlessness at night, and loss of appetite. Catching these changes early, rather than waiting for obvious distress, gives your vet the best chance of adjusting treatment before a crisis.