A routine checkup can turn up something unexpected, and a sound your veterinarian hears through a stethoscope can send your thoughts racing. An echocardiogram for dog with heart murmur evaluation is often the next step, and understanding it can bring real peace of mind.
Hearing that your dog has a heart murmur is worrying. This guide explains what a murmur is, what can cause one, what a veterinary echocardiogram shows and how the results guide treatment and monitoring. For our service, see echocardiogram for dogs.
Understanding Heart Murmurs in Dogs
A heart murmur is an abnormal sound heard during the heartbeat and is caused by turbulent blood flow. The sound offers clues, but it does not show how the heart looks inside or how well it works. Some murmurs are harmless and some point to a serious problem, so a murmur always calls for a plan.
What Causes a Heart Murmur
| Cause | What the sources say |
| Mitral valve disease | The leading heart disease in dogs, especially small breeds, and the usual cause of a murmur heard over the left apex |
| Congenital heart defects | Structural problems present from birth |
| Anemia or fever | Can change blood flow and cause a temporary functional murmur |
| Heartworm disease | The AVMA reports adult worms live in the heart and blood vessels of the lungs |
| Heart muscle disease | Weakens or thickens the heart muscle |
A survey of veterinary practitioners describes myxomatous mitral valve degeneration as the most common heart disease in dogs. The AVMA explains that heartworm lives in the heart and lungs, which is one more reason for year round prevention. A murmur is the first step. Finding out why it is there takes more testing.
Why an Echocardiogram Is Essential
A physical exam can detect a murmur, but it cannot show why it is there or how it affects the heart. An echocardiogram is a noninvasive ultrasound that uses sound waves to make moving images of the heart. It shows the chambers and the valves and the blood flow as the heart beats.
X rays show heart size and the lungs, and they have a role. The ACVIM guidelines say that echocardiography is used to separate dogs with early valve disease from those with enlargement and that radiographs can substitute when echocardiography is unavailable. Echocardiography gives the more direct view. Ask your veterinarian which tests suit your dog.
What an Echocardiogram Reveals
| What it shows | Why it matters |
| Chamber size and wall thickness | Shows enlargement or thickening |
| Valve movement and leakage | Shows how bad the valve disease is |
| Blood flow speed and direction | Shows where blood is leaking or narrowed |
| Heart muscle contraction | Shows how well the heart pumps |
| Congenital defects | Finds holes or abnormal connections |
| Masses or fluid around the heart | Finds tumors and pericardial fluid |
This detail moves a dog from “has a murmur” to a specific diagnosis. See our cardiology service for more on cardiac issues in dogs.
The Echocardiogram Procedure: What to Expect
The test is usually straightforward. The steps are:
- Preparation: Your dog lies on a table and a small patch of fur on the chest may be shaved for good contact.
- Imaging: Gel is applied and a handheld probe captures images from several angles. It is painless.
- Calm handling: Most dogs need little or no sedation, though an anxious dog may need help to settle.
- Results: A trained veterinarian reviews the images, and your veterinarian explains the findings and plan.
The length of the visit varies, and your veterinarian will tell you how long to plan for. The sources used here do not give a standard duration.
Interpreting Echocardiogram Results
Results are used to classify the heart condition and its severity. The ACVIM guidelines divide mitral valve disease into stages. Stage B covers dogs with a murmur and no signs of heart failure. Stage B1 dogs have normal sized hearts. Stage B2 dogs have enlargement of the left atrium and ventricle.
The ACVIM guidelines list four criteria that identify stage B2: a murmur intensity of 3 out of 6 or more, a left atrium to aorta ratio of 1.6 or more on echocardiography, a normalized left ventricular diameter of 1.7 or more and a vertebral heart score above 10.5 on X rays. Your veterinarian applies these to your dog’s results.
Impact on Treatment and Prognosis
The stage guides treatment. The ACVIM guidelines recommend pimobendan for dogs that meet stage B2 criteria, to delay the onset of heart failure, and they recommend dietary treatment. For stage C, dogs with current or past signs of heart failure, the guidelines describe standard treatment that includes furosemide and pimobendan. Dogs in the early stage B1 have normal sized hearts and the guidelines recommend monitoring. The survey of practitioners found that 93 percent recommended no treatment at stage B1. Your veterinarian explains the plan and prognosis for your dog.
Living With a Dog With a Heart Murmur
After a diagnosis, care becomes an ongoing partnership with your veterinarian. Do not start or stop any medicine without veterinary advice.
Ongoing Monitoring and Follow Up
Dogs with murmurs need regular recheck exams. The ACVIM guidelines suggest reevaluation by echocardiography, or by radiography when echocardiography is unavailable, in 6 to 12 months depending on the imaging results, and some panelists recommend more frequent follow up in large dogs. Your veterinarian may also recommend blood tests and chest X rays. Call your veterinarian between visits if you notice coughing, tiring easily or breathing changes.
Quality of Life Considerations
Dogs with heart disease can often live comfortably with treatment and monitoring, and your veterinarian will guide diet and exercise. Keep exercise within what your dog tolerates. Create a calm routine. Know the signs of worsening heart failure, such as coughing, lethargy or difficulty breathing, and seek prompt care. For help with emergency signs, see this article on emergency vet care and how to recognize when your pet needs immediate attention.
The Role of Preventive Care
Some heart disease is genetic or related to age and cannot be prevented, but regular exams can find a murmur early. The ACVIM guidelines define stage A as a dog of a predisposed breed with no murmur or heart changes, so your veterinarian may follow certain breeds more closely. Year round heartworm prevention protects the heart from a preventable disease. For more, see this guide on why early detection of heart disease in pets is crucial and this piece on why preventive care for pets is crucial for early detection of health issues.
What the Sources Cannot Tell You
The ACVIM guidelines cover mitral valve disease in dogs and not every cause of a murmur. They do not give a life expectancy for your dog, and they are from 2019. The sources do not give the length of an echocardiogram or the training of the person who reads it. Your veterinarian decides which tests your dog needs.
Getting Clear Answers About Your Dog’s Heart
A murmur is a clue and an echocardiogram is how the clue becomes an answer. Knowing the cause and stage lets your veterinarian choose treatment and a monitoring schedule that fit your dog.
At Kainer Veterinary Hospital, our team offers advanced cardiac care and compassionate guidance for dogs with murmurs and other heart conditions. Contact us today to schedule a cardiac evaluation.
Sources
Keene et al., ACVIM Consensus Guidelines for the Diagnosis and Treatment of Myxomatous Mitral Valve Disease in Dogs, Journal of Veterinary Internal Medicine (2019).
Peer reviewed professional consensus guidelines.
Supports the staging, the stage B2 criteria, echocardiography versus radiography, pimobendan and diet, the follow up interval and stage A.
Self-Reported Utilization of International Guidelines for Staging Dogs with Myxomatous Mitral Valve Degeneration, A Survey among Veterinary Practitioners (accessed 2026).
Peer reviewed survey.
Supports the statement that mitral valve disease is the leading canine heart disease and the 93 percent figure for stage B1.
American Veterinary Medical Association, Heartworm Disease (accessed 2026).
Professional veterinary association.
Supports the statement that heartworm lives in the heart and lungs and year round prevention.
FAQs
Q: What is an echocardiogram for a dog with a heart murmur?
A: It is a noninvasive ultrasound of the heart that shows its structure and function. For a dog with a murmur it helps find the cause and judge how far a condition such as mitral valve disease has progressed.
Q: Why does my dog with a heart murmur need an echocardiogram?
A: A stethoscope detects the murmur but cannot show chamber size or valve function. The ACVIM guidelines use echocardiography to separate early disease from enlargement that needs treatment.
Q: How is an echocardiogram performed on a dog?
A: Your dog usually lies on a table while a probe with gel is moved over the chest. It is painless and often needs little or no sedation. An anxious dog may need help to settle.
Q: When should a dog with a heart murmur get an echocardiogram?
A: Your veterinarian recommends one for a new or loud murmur or when signs such as coughing or breathing changes appear. The ACVIM guidelines suggest rechecks in 6 to 12 months depending on the results.
Q: Can X rays replace an echocardiogram?
A: X rays show heart size and the lungs. The ACVIM guidelines say radiographs can stand in when echocardiography is unavailable, but echocardiography is the more direct test.
