A dog with a heart murmur and kidney disease may have two separate conditions, or the problems may be connected through changes in blood pressure and circulation. A heart murmur is a sound caused by turbulent blood flow and does not, by itself, mean that a dog has significant heart disease. Likewise, kidney disease can range from mild, early dysfunction with few visible signs to advanced disease affecting multiple organs.
The connection becomes more important when a dog has both a known heart problem and abnormal kidney tests. The heart and kidneys depend on adequate blood flow and blood pressure to function properly, while kidney disease can contribute to high blood pressure that affects the cardiovascular system. Some treatments for advanced heart disease and kidney disease also need to be carefully balanced because they can affect fluid balance, blood pressure, and kidney function.
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Dog Heart Murmur and Kidney Disease: Why It Happens
A dog can have a heart murmur and kidney disease at the same time because both conditions become more common with age, and changes in one body system can affect the other.
Kidney disease can cause high blood pressure and changes in fluid balance, which may place additional strain on the cardiovascular system. Some dogs may also develop a murmur from an unrelated heart condition.
The presence of a heart murmur does not necessarily mean that kidney disease caused it, nor does a murmur confirm heart failure.
A veterinarian may recommend blood and urine tests, blood-pressure measurement, chest imaging, or an echocardiogram to determine what is causing the murmur and assess kidney function.
Dog Heart Murmur and Kidney Disease: Common Causes
A Heart Murmur With Unrelated Kidney Disease
One of the simplest explanations is that the dog has a heart murmur and kidney disease that developed independently.
Heart murmurs can occur for many reasons, including valve disease, congenital heart abnormalities, changes in blood flow, or other cardiovascular conditions.
Some murmurs, particularly in young puppies, can be innocent and unrelated to structural heart disease.
Kidney disease is also common in older dogs and can develop separately from a heart condition.
Chronic kidney disease may progress for months or years before obvious symptoms appear.
Therefore, finding both conditions does not necessarily mean that one caused the other.
Related: Dog Diarrhea and Kidney Disease (What you should know)
Chronic Kidney Disease and High Blood Pressure
Kidney disease can contribute to systemic hypertension. In dogs with chronic kidney disease, high blood pressure can further damage the kidneys and can also affect organs including the heart, eyes, brain, and blood vessels.
This creates an important connection between kidney disease and cardiovascular health.
A dog with kidney disease and a heart murmur may therefore need blood pressure monitoring, particularly if the veterinarian has other reasons to suspect hypertension.
Heart Disease Affecting Kidney Blood Flow
Severe heart disease can interfere with normal circulation. When cardiac output is reduced, the kidneys may receive less effective blood flow, which can contribute to abnormal kidney function or an increase in waste products in the blood.
Azotemia, or elevated waste products in the blood, can occur with congestive heart failure as well as with kidney disease, dehydration, and other conditions.
This means abnormal kidney blood-test results do not always prove that the kidneys themselves are the original problem.
The veterinarian must consider the dog’s cardiovascular status, hydration, blood pressure, medications, and kidney testing together.
Related: Old Dog Kidney Failure (Signs, stages and causes)
Heart Failure and Kidney Problems
A heart murmur does not automatically mean heart failure. Many dogs have heart disease without developing congestive heart failure, and some murmurs may not represent serious structural disease.
When severe heart disease progresses to heart failure, however, circulation and fluid balance can become abnormal.
This may complicate kidney function and make management more challenging.
Signs of heart failure can include coughing, difficulty breathing, exercise intolerance, faster breathing at rest, weakness, or fainting.
Right-sided heart failure can also cause fluid accumulation in the abdomen or other tissues.
Kidney Disease With a Heart Murmur in an Older Dog
Older dogs are more likely to develop both chronic kidney disease and acquired heart disease.
Degenerative valve disease is the most common acquired heart disease in dogs, while chronic kidney disease becomes increasingly common with age.
An older dog diagnosed with both conditions therefore does not necessarily have one disease causing the other. Both may simply have become apparent during the same period of life.
The important question is how well each organ system is functioning and whether either condition is progressing.
Anemia and a Heart Murmur
Kidney disease can cause anemia because damaged kidneys may produce less erythropoietin, a hormone involved in red blood cell production.
Anemia can alter blood flow and may contribute to a heart murmur caused by increased or turbulent blood flow.
This is different from a murmur caused by a damaged heart valve or other structural heart disease.
For this reason, bloodwork is important when a dog has a newly detected murmur alongside kidney abnormalities.
High Blood Pressure From Another Condition
Kidney disease is a major cause of secondary hypertension in dogs, but it is not the only possible cause. Hormonal disorders and other diseases can also raise blood pressure.
High blood pressure can place additional strain on the cardiovascular system and can damage organs when it is severe or persistent.
A dog with a murmur and suspected kidney disease may therefore need blood pressure measurement as part of the overall assessment.
Related: Dog shaking panting and kidney disease (What it means)
Dog Heart Murmur and Kidney Disease but Acting Normal
A dog can have both a heart murmur and kidney disease while still appearing completely normal.
This is particularly possible in early kidney disease or early-stage heart disease.
Chronic kidney disease can progress for a long time before obvious signs develop, while many dogs with heart disease also have no clinical signs until the disease becomes more advanced.
Acting normally is reassuring, but it does not determine the severity of either condition.
Routine bloodwork, urinalysis, blood pressure measurement, and appropriate cardiac evaluation may identify abnormalities before a dog becomes visibly ill.
Dog Heart Murmur and Kidney Disease With Increased Thirst and Urination
Increased thirst and urination can occur with chronic kidney disease, particularly as the kidneys become less able to concentrate urine.
These signs are not specific to kidney disease, however. Diabetes and several hormonal or metabolic disorders can produce similar changes.
If a dog with a heart murmur develops noticeable changes in drinking or urination, the veterinarian may recommend blood and urine testing to determine whether kidney function has changed.
Dog Heart Murmur and Kidney Disease With Coughing
Coughing in a dog with a heart murmur should not automatically be attributed to either the murmur or kidney disease.
Some forms of heart disease can progress to left-sided congestive heart failure, in which fluid accumulates in the lungs and causes coughing and breathing difficulty.
Dogs can also cough because of respiratory disease unrelated to the heart.
Kidney disease alone is not usually assumed to be the cause of a cough, so the dog’s heart, lungs, and overall health need to be assessed when coughing develops.
Dog Heart Murmur and Kidney Disease With Vomiting
Vomiting can occur with advanced kidney dysfunction when waste products accumulate in the blood. Severe kidney disease may also cause dehydration, poor appetite, weight loss, and other systemic signs.
A dog with significant heart disease can also develop gastrointestinal signs indirectly through poor circulation, medication effects, or complications of its underlying condition.
Repeated vomiting is important because dehydration can further complicate both kidney function and cardiovascular stability.
Dog Heart Murmur and Kidney Disease With Lethargy
Lethargy can occur with advanced kidney disease, heart failure, anemia, or many unrelated illnesses.
Kidney disease can cause anemia and the accumulation of waste products, while severe heart disease can reduce the body’s ability to maintain adequate circulation and oxygen delivery.
Because lethargy is nonspecific, it cannot establish whether the heart, kidneys, or another organ system is responsible.
When to Call or Visit the Vet
Arrange a veterinary examination if your dog has a heart murmur and known or suspected kidney disease, particularly if you notice:
Increased thirst or urination
Reduced appetite or weight loss
Vomiting or persistent nausea
Increasing lethargy or weakness
Coughing or reduced exercise tolerance
Faster or more difficult breathing
Fainting or collapse
A swollen abdomen
Pale, blue, or otherwise abnormal gums
Changes in urination
Dehydration
Sudden vision changes
A known increase in blood pressure
Worsening kidney blood-test results
A newly detected or changing heart murmur
Immediate veterinary attention is warranted for difficulty breathing, collapse, severe weakness, repeated vomiting with inability to keep water down, sudden blindness, or inability to urinate.
Severe heart failure and serious kidney or urinary problems can become medically urgent.
Dog Heart Murmur and Kidney Disease: Treatment
Treatment depends on whether the dog has an innocent murmur, structural heart disease, kidney disease, or a combination of conditions.
The veterinarian may evaluate the heart with a physical examination, blood pressure measurement, chest X-rays, electrocardiography, and echocardiography when indicated.
Kidney assessment may include blood chemistry, urinalysis, urine protein testing, blood pressure measurement, and additional imaging or testing when appropriate.
Treatment is then tailored to the specific diagnoses and their severity. When heart and kidney disease occur together, the veterinarian may need to balance fluid status, blood pressure, and medications carefully because changes intended to help one organ system can affect the other.
Key Takeaway
A dog with a heart murmur and kidney disease does not necessarily have one condition causing the other.
A murmur can result from structural heart disease, altered blood flow, or an innocent finding, while kidney disease can develop independently, particularly in older dogs.
There is nevertheless an important connection between the heart and kidneys. Severe heart disease can affect circulation to the kidneys, while kidney disease can contribute to high blood pressure that damages the cardiovascular system and other organs.
If your dog has both conditions, regular monitoring of kidney function, blood pressure, heart function, hydration, and clinical signs can help the veterinarian determine how the diseases are interacting and adjust treatment appropriately.