A heart murmur in dogs is an abnormal sound heard between the normal “lub-dub” heartbeats. It is caused by turbulent blood flow within or near the heart, rather than smooth, laminar flow.<\/span><\/p>\n Not all murmurs indicate serious disease. Some are normal, especially in young puppies, and resolve on their own. Others signal structural heart disease that warrants investigation and treatment. A <\/span>pet health expert<\/span><\/a> needs to assess every new murmur, regardless of how soft it sounds.<\/span><\/p>\n Dog murmur grades are assigned using the six-point Levine scale, the standard system used in both human and veterinary cardiology. Canine heart murmur grades are assessed during a stethoscope examination in a quiet room, with the dog at rest.<\/span><\/p>\n Each grade reflects loudness and whether a thrill (a vibration palpable through the chest wall) is present. Grade alone does not reveal the cause. That requires further investigation.<\/span><\/p>\n Canine heart murmur grades run from 1 (nearly inaudible) to 6 (heard with the stethoscope held off the chest). The grading system helps vets communicate severity and make consistent decisions about next steps.<\/span><\/p>\n Grade 1 is the softest murmur possible, heard only by an experienced vet in complete quiet. Grade 2 is soft but audible on initial auscultation. No thrill is present at either grade.<\/span><\/p>\n In young puppies (typically under 16 weeks), Grade 1-2 murmurs are often innocent and resolve as the heart matures. In adult dogs, even soft murmurs warrant investigation. Regular echocardiographic monitoring allows any changes to be detected early.<\/span><\/p>\n Grade 3 is a moderate murmur, easy to hear but without a palpable thrill. Grade 4 is louder and accompanied by a thrill at the point of maximum intensity.<\/span><\/p>\n In middle-aged and older small-breed dogs, such as <\/span>Chihuahuas<\/span><\/a> and Poodles, Grade 3-4 murmurs most commonly indicate myxomatous mitral valve disease (MMVD). Echocardiography is strongly recommended at this stage to assess cardiac structure.\u00a0<\/span><\/p>\n The 2019 ACVIM Consensus Guidelines now recommend pimobendan for qualifying dogs, even before symptoms appear. The qualifying criterion is left atrial and ventricular enlargement on echo (Stage B2).<\/span><\/p>\n Grade 5 is very loud, with a palpable thrill, and can be heard with the stethoscope lightly touching the chest. Grade 6 is the loudest possible murmur: audible with the stethoscope held off the chest, with a prominent thrill.<\/span><\/p>\n Grade 5-6 murmurs are almost always associated with significant structural heart disease. Most dogs at this grade have symptoms or are at high risk of developing them soon. <\/span>Echocardiography, <\/span>chest X-rays<\/span><\/a>, and treatment planning are standard next steps.<\/span><\/p>\n Any canine heart murmur needs a cause to be identified, as treatment varies widely depending on what is driving it. Common causes include:<\/span><\/p>\n A dog murmur detected at a routine check-up is often caught before any symptoms develop. This is one of the most important reasons for annual auscultation at every vet visit.<\/span><\/p>\n When symptoms appear, they typically signal progression towards or into congestive heart failure:<\/span><\/p>\n A resting respiratory rate above 30 breaths per minute is an early warning sign of fluid accumulating in the lungs. Pet parents can count this at home while their dog is asleep.<\/span><\/p>\n Auscultation gives the vet the grade, location, timing (systolic or diastolic), and character of the murmur. This guides the next steps.<\/span><\/p>\n Echocardiography (ultrasound of the heart) is the gold standard for diagnosis. It shows valve anatomy, chamber sizes, and systolic function: none of these can be determined by grade alone. Chest X-rays assess heart size using the vertebral heart score and reveal changes in the lung fields. An ECG detects arrhythmias.<\/span><\/p>\n The NT-proBNP blood test measures a biomarker released in response to cardiac stress and helps distinguish cardiac from non-cardiac causes of symptoms. Blood pressure monitoring is also standard in older dogs with murmurs.<\/span><\/p>\n Not every murmur needs medication. The decision depends on grade, echo findings, clinical signs, and underlying cause.<\/span><\/p>\n Canine heart murmur grades of 1-2 with no structural disease on echo: monitoring only. No medication is typically recommended at this stage.<\/span><\/p>\n For Stage B2 MMVD (specific echo criteria met), pimobendan is now recommended to delay heart failure onset, even without symptoms.<\/span><\/p>\n Dogs in congestive heart failure (Stage C or D): pimobendan combined with frusemide, with spironolactone added in many protocols. Congenital defects such as PDA may require interventional or surgical correction.<\/span><\/p>\n For a dog diagnosed with a heart murmur, the focus shifts to monitoring and lifestyle adjustments. This does not always mean a drastic change in daily life, especially for lower-grade murmurs.<\/span><\/p>\n Key home management principles:<\/span><\/p>\n Prognosis varies considerably by cause and stage. Healthy puppy murmurs have an excellent prognosis and typically resolve on their own. Dogs with MMVD detected early, especially those starting pimobendan in Stage B2, have significantly extended periods before heart failure develops.<\/span><\/p>\n Once congestive heart failure is present, the condition is managed rather than cured. Median survival with treatment is approximately nine to twelve months, though many dogs exceed this with careful management and monitoring.<\/span><\/p>\n Heart disease is progressive in most cases. Regular echocardiography (every six to twelve months, depending on stage) lets the <\/span>experienced vet for dogs<\/span><\/a> adjust treatment before the condition worsens.<\/span><\/p>\n Canine heart murmur grades are one piece of a larger clinical picture, not a verdict in isolation. A Grade 2 murmur in a puppy is very different from a Grade 2 murmur in a seven-year-old Cavalier. Context matters. That context comes from a thorough veterinary assessment.<\/span><\/p>\n If your dog has been diagnosed with a heart murmur, book a consultation with a vet. Early detection and monitoring make the biggest difference to long-term outcomes.<\/span><\/p>\n Many dogs with low-grade murmurs live normal, comfortable lives for years without ever developing symptoms.\u00a0<\/span><\/p>\n No. Grade 1-2 murmurs without structural disease on echocardiography are monitored rather than medicated. Grade 3-4 murmurs that meet specific echo criteria per ACVIM guidelines may benefit from pimobendan before symptoms appear.<\/span><\/p>\n In most structural heart diseases, yes. MMVD is a progressive condition, and the murmur grade typically increases as the disease advances.<\/span><\/p>\n Grade 5-6 is almost always associated with significant structural disease. Grade 3-4 requires echocardiography to determine clinical significance. But even a Grade 1-2 murmur in a predisposed breed (such as a Cavalier King Charles Spaniel) deserves investigation.<\/span><\/p>\n <\/p>\n Boswood, A. (2018). <\/span><\/i><\/i><\/i><\/i><\/i>Approach to the Dog with a Heart Murmur<\/span><\/i>.<\/span> VIN. <\/span>https:\/\/www.vin.com\/apputil\/content\/defaultadv1.aspx?pId=22915&id=8896687<\/span><\/a>\u00a0<\/span><\/p>\n Campbell, F. E. (2015, March 30). <\/span><\/i><\/i><\/i><\/i><\/i>Cardiac Disease and Examination<\/span><\/i>.<\/span> VIN. <\/span>https:\/\/www.vin.com\/apputil\/content\/defaultadv1.aspx?pId=11372&id=5709745&print=1<\/span><\/a>\u00a0<\/span><\/p>\n Sleeper, M. (n.d.). <\/span><\/i><\/i><\/i><\/i><\/i>How to stage heart disease, part I<\/span><\/i>.<\/span> Retrieved June 29, 2026, from <\/span>https:\/\/www.canadianveterinarians.net\/media\/mm3jl2yh\/slides-how-to-stage-heart-disease-part-1.pdf<\/span><\/a><\/p>\n","protected":false},"excerpt":{"rendered":" What Is a Heart Murmur in Dogs? A heart murmur in dogs is an abnormal sound heard between the normal “lub-dub” heartbeats. It is caused by turbulent blood flow within…<\/p>\n","protected":false},"author":15,"featured_media":8667,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_lmt_disableupdate":"","_lmt_disable":"","footnotes":""},"categories":[64],"tags":[],"class_list":["post-8665","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-pet-health"],"acf":[],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\tHow Veterinarians Grade Heart Murmurs in Dogs<\/b><\/h2>\n
Understanding Heart Murmur in Dogs: Grades 1 to 6<\/b><\/h2>\n
Grade 1-2 Heart Murmurs<\/b><\/h3>\n
Grade 3-4 Heart Murmurs<\/b><\/h3>\n
Grade 5-6 Heart Murmurs<\/b><\/h3>\n
Common Causes of Heart Murmurs in Dogs<\/b><\/h2>\n
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Symptoms That May Accompany a Heart Murmur<\/b><\/h2>\n
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How Canine Heart Murmurs Are Diagnosed<\/b><\/h2>\n
When a Heart Murmur Requires Treatment<\/b><\/h2>\n
Living With a Dog Diagnosed With a Heart Murmur<\/b><\/h2>\n
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Prognosis and Long-Term Monitoring of Heart Murmurs in Dogs<\/b><\/h2>\n
Final Thoughts: About Canine Heart Murmur Grades<\/b><\/h2>\n
FAQs: About Canine Heart Murmur Grades<\/b><\/h2>\n
Can a dog live a normal life with a heart murmur?<\/b><\/h3>\n
Does every heart murmur require medication?<\/b><\/h3>\n
Can heart murmurs get worse over time?<\/b><\/h3>\n
What grade of heart murmur is considered serious?<\/b><\/h3>\n
References<\/b><\/h2>\n