Dogs with heartworms need a diet that supports their heart, maintains muscle mass, and keeps sodium in check. The right food choices can make a real difference in how well your dog handles both the disease and the treatment process. What you feed depends partly on how advanced the disease is, whether your dog is showing symptoms like coughing or fatigue, and whether heart failure has developed.
Why Diet Matters During Heartworm Disease
Heartworms live in the heart and pulmonary arteries, forcing the heart to work harder to pump blood. Over time, this extra strain can lead to heart enlargement and, in severe cases, congestive heart failure. The inflammation caused by the worms and the stress on the cardiovascular system both increase your dog’s nutritional needs in specific ways. A dog eating the wrong diet, or not eating enough, can lose muscle mass and struggle more during treatment.
Treatment itself adds another layer. The injections used to kill adult heartworms commonly cause decreased appetite, vomiting, and diarrhea in the days following each shot. Planning ahead with the right foods and feeding strategies helps your dog stay nourished through the process.
Keep Sodium Low
Sodium restriction is one of the most important dietary changes for a dog with heartworm disease. Excess sodium causes the body to retain fluid, which puts additional pressure on an already strained heart. For dogs with mild disease and no visible symptoms, only mild sodium restriction is necessary. If your dog has progressed to congestive heart failure, stricter limits become important.
A practical rule from Tufts Veterinary School: aim for less than 100 mg of sodium per 100 kilocalories of food. This applies to everything your dog eats, including treats, pill pockets, and any table scraps. Many commercial dog treats are surprisingly high in sodium, so check labels carefully. Common human foods to avoid entirely include deli meats, cheese, bread, canned soups, hot dogs, and most processed snacks. Even some commercial dog foods marketed as “premium” can have sodium levels too high for a dog with heart involvement.
Fresh, unseasoned lean meats, plain cooked vegetables like green beans or sweet potatoes, and low-sodium commercial diets are all safer options. If you’re using pill pockets to give medication, verify they meet the sodium threshold before making them part of your dog’s daily routine.
Prioritize High-Quality Protein
Dogs with heart disease are prone to a condition called cardiac cachexia, a progressive loss of lean muscle mass driven by the body’s inflammatory response to the disease. This muscle wasting can happen even if your dog appears to be eating normally, and it weakens the body at a time when strength matters most.
Older veterinary advice sometimes recommended restricting protein for dogs with heart problems, but that guidance has been reversed. There is no evidence that protein restriction helps dogs with heart failure, and it likely makes things worse by accelerating muscle loss. Unless your dog also has significant kidney disease, you should feed high-quality protein at a minimum of 5.1 grams per 100 kilocalories. Good sources include chicken, turkey, eggs, and fish. These provide the amino acids your dog’s body needs to maintain and rebuild muscle tissue during a physically demanding time.
Add Omega-3 Fatty Acids
Omega-3 fatty acids, specifically EPA and DHA found in fish oil, have documented cardiovascular benefits in dogs. Heart failure is fundamentally an inflammatory disease, and these fatty acids help reduce that inflammation. They also support healthy heart rhythm and can improve appetite.
A commonly recommended dose is one standard fish oil capsule (containing 180 mg EPA and 120 mg DHA) per 10 pounds of body weight. So a 50-pound dog would get five capsules daily. You can puncture the capsules and squeeze the oil onto food if your dog won’t swallow them whole. Look for fish oil products made specifically for dogs, or use human-grade fish oil without added flavoring. Avoid cod liver oil, which contains high levels of vitamins A and D that can build up to toxic levels.
Support Heart Function With Key Nutrients
Two amino acids play important roles in heart health for dogs: taurine and L-carnitine. Taurine is essential for normal cardiac muscle function. Research has shown that dogs with low taurine levels can develop a form of heart disease called dilated cardiomyopathy, where the heart muscle weakens and can’t pump effectively. When those dogs received taurine supplementation, their cardiac function improved substantially. Dogs on protein-restricted diets are especially vulnerable to taurine deficiency, which is another reason to keep protein levels adequate.
L-carnitine helps the heart muscle convert fat into energy. Both nutrients are found naturally in red meat and organ meats like liver and heart. If your dog’s diet is primarily poultry-based or uses a limited protein source, ask your vet about supplementation. The appropriate dose varies by dog size and disease severity.
Watch Electrolytes If Your Dog Takes Diuretics
Dogs with more advanced heartworm disease sometimes need diuretic medications to reduce fluid buildup. These medications work well for that purpose, but they also flush potassium and magnesium out of the body. Research on dogs receiving diuretic therapy for heart failure found statistically significant drops in both potassium and magnesium levels, and those drops can cause dangerous heart rhythm disturbances. Dogs on diuretics who developed irregular heartbeats had even lower potassium than other diuretic-treated dogs.
Since potassium and magnesium are stored mostly inside cells, blood tests may underestimate the true deficit. Foods naturally rich in potassium include pumpkin, sweet potatoes, bananas (in small amounts), and spinach. Your vet may also recommend a potassium or magnesium supplement depending on bloodwork results.
Managing Appetite During Treatment
The injections that kill adult heartworms commonly cause gastrointestinal side effects, including vomiting, diarrhea, and reduced appetite for up to 10 days after each shot. Your dog may also receive pain medication during this period, which can further affect appetite. This is a time when getting calories in matters more than dietary perfection.
Warming food slightly can make it more aromatic and appealing. Offering smaller, more frequent meals (three or four times daily instead of two) reduces the burden on a queasy stomach. Bland, easily digestible options like boiled chicken with plain white rice or scrambled eggs (no butter or salt) are gentle on the digestive system and usually well-tolerated. Bone broth, homemade with no added salt or onions, can entice a reluctant eater and provides hydration at the same time.
If your dog refuses kibble entirely during recovery, try mixing in a small amount of low-sodium wet food or a spoonful of plain canned pumpkin. The goal is to keep your dog eating consistently, even if portions are smaller than normal for a few days.
Keep Fresh Water Available
Dogs with heartworm disease often drink more water than usual, and this increases further if they’re on diuretic medications. Always keep fresh water accessible. Never restrict water intake unless specifically directed to do so. Dehydration puts additional stress on the kidneys and cardiovascular system, both of which are already under pressure. If you notice your dog’s water consumption suddenly increasing or decreasing dramatically, that’s worth mentioning to your vet as it can signal changes in heart function or medication effects.
Putting It All Together
The ideal diet for a dog with heartworms is low in sodium, rich in high-quality protein, and supplemented with omega-3 fatty acids. It should include enough potassium and magnesium to offset any losses from medications, and enough taurine and L-carnitine to support heart muscle function. Whether you’re feeding commercial food or a home-prepared diet, check sodium levels on everything that goes into your dog’s mouth, including treats and pill delivery aids.
A commercial cardiac diet formulated for dogs with heart disease will meet most of these criteria out of the box. Several veterinary brands make prescription cardiac formulas that are sodium-restricted with appropriate protein levels. If you prefer to cook for your dog, work with a veterinary nutritionist to ensure the diet is balanced, as homemade cardiac diets are easy to get wrong without professional guidance. Your dog’s nutritional needs may also shift as the disease progresses or improves with treatment, so revisit the feeding plan at each vet visit.