# Echocardiography in the Diagnostic Workup of Heart Murmurs ## Quick Answer - Echocardiography is the definitive imaging method for characterizing heart murmurs, distinguishing physiologic from pathologic causes, and guiding treatment decisions in veterinary patients. - The decision to perform echocardiography depends on murmur grade, location, clinical signs, patient age and breed, and whether the murmur persists or changes over serial examinations. - A key limitation is that echocardiography requires specialized training and equipment, and a normal study does not exclude all cardiac disease, so clinical judgment remains essential. ## At a Glance | Clinical Scenario | Recommended Action | Key Echocardiographic Findings | Escalation Criteria | |---|---|---|---| | Asymptomatic puppy with soft systolic murmur | Recheck in 4 to 6 weeks, consider echocardiography if murmur persists beyond 6 months of age | Normal chamber sizes, no structural lesions, possible physiologic or innocent murmur | Persistent murmur, syncope, or exercise intolerance warrants referral to a veterinary cardiologist | | Adult dog with grade 3 or louder systolic murmur and cough | Perform echocardiography to assess for myxomatous mitral valve disease | Thickened mitral valve leaflets, mitral regurgitation, left atrial enlargement | Respiratory distress, collapse, or progressive exercise intolerance | | Cat with gallop rhythm or murmur and respiratory signs | Perform echocardiography promptly to differentiate hypertrophic cardiomyopathy from other causes | Increased left ventricular wall thickness, left atrial enlargement, possible systolic anterior motion of the mitral valve | Acute dyspnea, hindlimb paresis, or suspected thromboembolism | | Horse with new murmur and poor performance | Echocardiography to evaluate for valvular regurgitation or congenital defects | Aortic or mitral regurgitation, ventricular septal defect, chamber enlargement | Sudden death risk, poor performance, or syncope | | Calf or lamb with continuous murmur | Echocardiography to assess for patent ductus arteriosus or other congenital shunts | Continuous turbulent flow, chamber enlargement, possible pulmonary hypertension | Failure to thrive, respiratory distress, or congestive heart failure | ## Clinical Context and the Role of Auscultation Heart murmurs are common findings in veterinary practice, and their presence often raises concern for underlying cardiac disease. Auscultation remains the first step in detecting a murmur, but it provides limited information about the underlying cause. The clinician must decide whether a murmur is clinically significant, whether it warrants further investigation, and when echocardiography is appropriate. Murmurs are classified by timing in the cardiac cycle, location of maximal intensity, grade, and quality. Systolic murmurs are the most common in dogs and cats, while diastolic murmurs are less frequent and often indicate valvular insufficiency. Continuous murmurs are rare and typically suggest a shunt lesion such as patent ductus arteriosus. The grade of a murmur, on a scale of 1 to 6, reflects its intensity, with higher grades often associated with more significant disease, although this is not always the case. Auscultation alone cannot reliably distinguish between physiologic and pathologic murmurs. Physiologic murmurs, also called functional or innocent murmurs, occur in the absence of structural heart disease and are common in young animals, particularly puppies. They are typically soft, systolic, and localized, and they often resolve as the animal matures. Pathologic murmurs, in contrast, are associated with structural abnormalities such as valvular disease, congenital defects, or cardiomyopathy. The decision to perform echocardiography is influenced by several factors, including the age and species of the animal, the murmur characteristics, the presence of clinical signs, and the results of other diagnostic tests. The American Veterinary Medical Association emphasizes the importance of regular veterinary care and preventive health examinations, which provide opportunities to detect murmurs and monitor their progression. The American Animal Hospital Association similarly supports life-stage-based preventive care, which includes cardiovascular assessment as part of a comprehensive physical examination. ## Core Principles of Echocardiography Echocardiography uses ultrasound to create real-time images of the heart, allowing the clinician to evaluate cardiac structure, function, and blood flow. It is a noninvasive technique that provides information that cannot be obtained from auscultation or radiography alone. The two main modalities are two-dimensional echocardiography, which provides structural images, and Doppler echocardiography, which assesses blood flow velocity and direction. Two-dimensional echocardiography allows the clinician to measure chamber dimensions, wall thickness, and valve morphology. It is used to identify structural lesions such as valvular thickening, chamber enlargement, and congenital defects. M-mode echocardiography, a subtype of two-dimensional imaging, provides a single-dimensional view of the heart over time and is used to measure ventricular function and wall motion. Doppler echocardiography includes several modes. Pulsed-wave Doppler measures blood flow at a specific location, while continuous-wave Doppler measures flow along a line. Color-flow Doppler superimposes color-coded blood flow information on the two-dimensional image, allowing the clinician to visualize regurgitant jets and shunts. These modalities are essential for quantifying the severity of valvular regurgitation and for identifying abnormal flow patterns. Echocardiography is performed by a veterinarian with specialized training, often a board-certified veterinary cardiologist. The procedure requires the animal to be restrained, and sedation may be used in anxious or uncooperative patients. The animal is typically positioned in lateral recumbency, and the transducer is placed on the chest wall. The study is recorded and reviewed, and measurements are taken to assess cardiac dimensions and function. The Merck Veterinary Manual provides authoritative background on cardiovascular disease in animals, including the use of echocardiography for diagnosis and monitoring. The manual emphasizes that echocardiography is a valuable tool for confirming a diagnosis, assessing the severity of disease, and guiding treatment decisions. ## When to Perform Echocardiography The decision to perform echocardiography is not based on the presence of a murmur alone. It is based on a combination of factors, including the murmur characteristics, the animal's age and breed, the presence of clinical signs, and the results of other diagnostic tests. ### Murmur Characteristics The grade, location, and quality of a murmur provide important clues about its significance. A soft, systolic murmur that is localized to the left apex is common in young animals and may be physiologic. A louder murmur, a diastolic murmur, or a murmur that is accompanied by a thrill is more likely to be associated with structural heart disease. A murmur that is continuous or that is heard in an unusual location may indicate a congenital defect. ### Age and Breed Age is a critical factor in the interpretation of murmurs. Puppies and kittens may have physiologic murmurs that resolve as they mature. However, a murmur that persists beyond six months of age or that is accompanied by clinical signs warrants further investigation. In older animals, a new murmur may indicate the onset of acquired heart disease, such as myxomatous mitral valve disease in dogs or hypertrophic cardiomyopathy in cats. Breed is also important. Certain breeds are predisposed to specific cardiac diseases. For example, Cavalier King Charles Spaniels are predisposed to myxomatous mitral valve disease, while Maine Coon cats are predisposed to hypertrophic cardiomyopathy. The presence of a murmur in a predisposed breed may warrant earlier echocardiography. ### Clinical Signs The presence of clinical signs is a strong indication for echocardiography. Signs of heart disease include cough, exercise intolerance, syncope, respiratory distress, and abdominal distension. These signs may indicate congestive heart failure or other significant cardiac disease. In these cases, echocardiography is essential for confirming the diagnosis and guiding treatment. ### Other Diagnostic Tests The results of other diagnostic tests may also influence the decision to perform echocardiography. Thoracic radiographs can reveal cardiomegaly, pulmonary edema, or other signs of heart disease. Electrocardiography can detect arrhythmias or conduction abnormalities. Blood tests may reveal evidence of organ dysfunction or other systemic disease. The presence of abnormalities on these tests may warrant echocardiography. ## Echocardiographic Measurements and Interpretation Echocardiography provides a range of measurements that are used to assess cardiac structure and function. These measurements are compared to reference ranges for the species and breed of the animal. ### Chamber Dimensions The size of the cardiac chambers is an important indicator of heart disease. Left atrial enlargement is a common finding in dogs with myxomatous mitral valve disease and in cats with hypertrophic cardiomyopathy. Left ventricular enlargement may be seen in dogs with dilated cardiomyopathy or with chronic volume overload. The left atrial-to-aortic root ratio is a commonly used measurement to assess left atrial size. ### Wall Thickness The thickness of the ventricular walls is measured to assess for hypertrophy. Increased left ventricular wall thickness is a hallmark of hypertrophic cardiomyopathy in cats. The measurement is typically taken in diastole, and the normal range varies by species and breed. ### Valvular Structure and Function Echocardiography allows the evaluation of the heart valves. The mitral valve is assessed for thickening, prolapse, and regurgitation. The aortic valve is assessed for thickening, stenosis, and regurgitation. The tricuspid valve and the pulmonary valve are also evaluated. Color-flow Doppler is used to identify regurgitant jets and to assess their severity. ### Ventricular Function Ventricular function is assessed using measurements such as the ejection fraction and the fractional shortening. These measurements are used to assess the systolic function of the heart. A reduced ejection fraction may indicate systolic dysfunction, which is seen in dilated cardiomyopathy. ### Doppler Measurements Doppler echocardiography is used to measure blood flow velocity and direction. It is used to assess the severity of valvular regurgitation and stenosis. The velocity of blood flow across a stenotic valve is increased, and the pressure gradient can be calculated. The direction of blood flow is used to identify shunts, such as a patent ductus arteriosus. ## Common Cardiac Diseases and Their Echocardiographic Findings Echocardiography is used to diagnose and characterize a variety of cardiac diseases. The findings are specific to the disease and are used to guide treatment. ### Myxomatous Mitral Valve Disease Myxomatous mitral valve disease is the most common acquired heart disease in dogs. It is characterized by thickening and prolapse of the mitral valve leaflets, leading to mitral regurgitation. Echocardiographic findings include thickening of the mitral valve leaflets, mitral regurgitation, and left atrial and left ventricular enlargement. The severity of the disease is graded based on the degree of regurgitation and the degree of chamber enlargement. ### Hypertrophic Cardiomyopathy Hypertrophic cardiomyopathy is the most common heart disease in cats. It is characterized by concentric hypertrophy of the left ventricle, leading to diastolic dysfunction. Echocardiographic findings include increased left ventricular wall thickness, left atrial enlargement, and possible systolic anterior motion of the mitral valve. The disease is graded based on the degree of hypertrophy and the presence of clinical signs. ### Dilated Cardiomyopathy Dilated cardiomyopathy is a disease of the myocardium that leads to systolic dysfunction and chamber enlargement. It is more common in large-breed dogs. Echocardiographic findings include left ventricular and left atrial enlargement, decreased ejection fraction, and decreased fractional shortening. ### Congenital Heart Disease Congenital heart disease includes a variety of defects, such as patent ductus arteriosus, ventricular septal defect, and aortic stenosis. Echocardiography is used to identify the defect, assess its severity, and guide treatment. The findings are specific to the defect. ## Practical Workflow for Murmur Evaluation A systematic approach to murmur evaluation is essential for making appropriate decisions about echocardiography. The following workflow provides a framework for the evaluation of a murmur in a veterinary patient. ### Step 1: Perform a Complete Physical Examination The physical examination is the first step in the evaluation of a murmur. The clinician should perform a thorough examination, including auscultation of the heart and lungs, assessment of the pulse, and evaluation of the mucous membranes. The murmur should be characterized by its grade, location, and quality. ### Step 2: Obtain a History A complete history is essential. The clinician should ask about the animal's age, breed, and sex, as well as any clinical signs such as cough, exercise intolerance, or syncope. The history should also include information about the animal's diet, lifestyle, and any previous medical conditions. ### Step 3: Perform a Physical Examination The physical examination should include a thorough assessment of the cardiovascular system. The clinician should assess the heart rate and rhythm, the pulse quality, and the presence of any murmurs or arrhythmias. The lungs should be auscultated for any signs of pulmonary edema or other respiratory disease. ### Step 4: Consider Additional Diagnostic Tests The results of the physical examination and history will determine the need for additional diagnostic tests. Thoracic radiography and electrocardiography may be performed to assess the heart and lungs. Blood tests may be used to assess for other systemic disease. ### Step 5: Decide Whether to Perform Echocardiography The decision to perform echocardiography is based on the clinical findings. The clinician should consider the murmur characteristics, the age and breed of the animal, the presence of clinical signs, and the results of other diagnostic tests. If the murmur is soft and the animal is asymptomatic, the clinician may choose to monitor the animal and recheck the murmur at a later date. If the murmur is loud, the animal is symptomatic, or the murmur is associated with other abnormalities, echocardiography is indicated. ### Step 6: Interpret the Echocardiographic Findings The echocardiographic findings should be interpreted in the context of the clinical findings. The clinician should assess the chamber dimensions, wall thickness, valvular function, and functional flow. The findings should be used to confirm or rule out a diagnosis and to guide the treatment. ### Step 7: Develop a Treatment Plan The treatment plan is based on the echocardiographic findings and the clinical signs. The plan may include medication, dietary changes, or surgery. The plan should be discussed with the owner, and the owner should be educated about the disease and the prognosis. ## Records and Measurements Accurate records are essential for the management of a patient with a heart murmur. The records should include the following information: - The date of the examination - The murmur characteristics, including the grade, location, and quality - The results of the physical examination - The results of any diagnostic tests - The echocardiographic measurements - The treatment plan - The follow-up schedule The echocardiographic measurements should be recorded in a standardized format. The measurements should include the left atrial diameter, the left ventricular diameter, the wall thickness, and the ejection fraction. The measurements should be compared to reference values for the species and age of the animal. ## Common Failure Patterns There are several common failure patterns in the evaluation of heart murmurs. These include: - Failing to perform a complete physical examination - Failing to obtain a detailed history - Failing to characterize the murmur - Failing to consider the age and breed of the animal - Failing to perform echocardiography when it is indicated - Failing to interpret the echocardiographic findings in the context of the clinical findings - Failing to develop a treatment plan ## Limitations of Echocardiography Echocardiography is a valuable diagnostic tool, but it has limitations. The quality of the images depends on the skill of the operator and the cooperation of the patient. The measurements are subject to variability, and the reference values may vary by species and breed. The study may not be able to detect all cardiac diseases, and a normal study does not exclude all cardiac disease. ## Welfare and Safety Context The welfare of the animal is a primary consideration in the evaluation of a heart murmur. The clinician should ensure that the animal is comfortable and that the procedure is performed in a safe and humane manner. The use of sedation may be necessary in some cases, but the risks and benefits should be considered. The World Organisation for Animal Health provides official guidance on animal health and welfare, and the American Veterinary Medical Association provides resources for pet owners. The welfare of the animal should be a primary consideration in all decisions. ## Professional Escalation Criteria The clinician should escalate the case to a veterinary cardiologist in the following situations: - The murmur is loud or is associated with clinical signs - The echocardiographic findings are complex or uncertain - The patient is not responding to treatment - The patient is a candidate for surgery or other advanced procedures ## A Structured Decision Framework for Murmur Triage and Echocardiographic Referral The decision to perform echocardiography in a patient with a heart murmur is rarely a binary choice. In practice, veterinarians face a spectrum of presentations, from an asymptomatic puppy with a soft murmur to a senior dog with a loud murmur and respiratory distress. A structured decision framework helps standardize the approach, reduce the risk of missing significant disease, and ensure that echocardiography is used when it will change management. This section provides a practical framework that integrates murmur characteristics, patient signalment, clinical signs, and point-of-care findings into a reproducible triage system. ### The Three-Tier Triage System A practical approach divides murmur cases into three tiers based on the urgency and necessity of echocardiography. This system is not a replacement for clinical judgment but provides a consistent starting point for decision making. **Tier 1: Monitor and Recheck** Tier 1 includes patients with a soft systolic murmur, typically grade 1 to 2 out of 6, that is localized, and the patient is asymptomatic. This category commonly includes young puppies and kittens with physiologic murmurs. The murmur is often heard best over the left heart base and may vary with heart rate, excitement, or body position. The patient has no cough, no exercise intolerance, no syncope, and no respiratory signs. The remainder of the physical examination is unremarkable, including normal pulse quality, normal mucous membrane color, and normal respiratory effort. For Tier 1 patients, the recommended action is to document the murmur characteristics in the medical record and schedule a recheck examination in 4 to 6 weeks. The owner should be educated about the expected course of a physiologic murmur and the specific signs that would warrant earlier re-evaluation. The American Veterinary Medical Association emphasizes the value of regular veterinary care and preventive health examinations, which provide the opportunity to monitor these patients over time. The American Animal Hospital Association similarly supports life-stage-based preventive care, which includes cardiovascular assessment as part of a comprehensive physical examination. If the murmur persists beyond 6 months of age in a puppy or kitten, or if it increases in grade, the patient should be moved to Tier 2 or Tier 3. A murmur that persists beyond this age is more likely to be associated with structural heart disease, such as a small ventricular septal defect or mild pulmonic stenosis. **Tier 2: Echocardiography Recommended** Tier 2 includes patients with a murmur that is grade 3 or louder, a murmur that is diastolic or continuous, or a murmur that is accompanied by any clinical sign that could be cardiac in origin. This tier also includes patients with a murmur and a known breed predisposition to cardiac disease, such as a Cavalier King Charles Spaniel with a murmur and a Maine Coon cat with a murmur. Clinical signs that warrant Tier 2 classification include cough, exercise intolerance, syncope, respiratory distress, abdominal distension, or poor growth in a young animal. The presence of a gallop rhythm, an arrhythmia, or a pulse deficit on physical examination also warrants Tier 2 classification. For Tier 2 patients, echocardiography is recommended to characterize the murmur and to guide treatment. The echocardiogram should be performed by a veterinarian with appropriate training, which may be a board-certified veterinary cardiologist or a general practitioner with advanced ultrasound training. The Merck Veterinary Manual provides authoritative background on cardiovascular disease in animals, including the use of echocardiography for diagnosis and monitoring. **Tier 3: Immediate Echocardiography and Emergency Stabilization** Tier 3 includes patients with a murmur and evidence of congestive heart failure or other life-threatening cardiac disease. Signs include severe respiratory distress, pale or cyanotic mucous membranes, weak or thready pulses, collapse, or suspected arterial thromboembolism, such as a cat with a painful, cold hindlimb. For Tier 3 patients, the priority is stabilization. Oxygen therapy, diuretics, and other emergency treatments should be initiated as indicated. Echocardiography should be performed as soon as the patient is stable enough to tolerate the procedure. In these cases, the echocardiogram is essential for confirming the diagnosis and guiding the treatment plan. ### The Murmur Scorecard A murmur scorecard is a practical tool for standardizing the assessment of a murmur and for tracking changes over time. The scorecard includes the following components: - **Grade:** The murmur grade on a scale of 1 to 6 - **Timing:** Systolic, diastolic, or continuous - **Location:** The point of maximal intensity, such as the left apex, left base, or right base - **Quality:** The character of the murmur, such as plateau, crescendo-decrescendo, or decrescendo - **Radiation:** Whether the murmur radiates to other areas of the chest or neck - **Thrill:** Whether a precordial thrill is palpable The scorecard should be completed at each examination and stored in the medical record. This allows the clinician to compare the murmur characteristics over time and to detect changes that may indicate progression of disease. For example, a murmur that was previously grade 2 and localized to the left apex may become grade 3 and radiate to the right chest, which may indicate worsening mitral regurgitation. ### The Echocardiographic Referral Checklist When the decision is made to refer a patient for echocardiography, the referring veterinarian should provide the cardiologist with a complete clinical summary. The summary should include the following: - The patient's signalment, including age, breed, and sex - The reason for the referral, including the murmur characteristics and any clinical signs - The results of the physical examination, including heart rate, rhythm, and pulse quality - The results of any other diagnostic tests, such as thoracic radiographs or electrocardiography - A list of current medications and the patient's response to treatment - The owner's concerns and expectations A complete referral summary allows the cardiologist to focus the echocardiographic examination and to interpret the findings in the context of the clinical presentation. The World Small Animal Veterinary Association provides global guidelines for companion-animal clinical practice, which can be used to support the referral process. ### Interpreting the Echocardiogram in the Context of the Framework The echocardiographic findings should be interpreted in the context of the triage tier and the clinical signs. A patient in Tier 1 who has a normal echocardiogram can be reassured that the murmur is likely physiologic. A patient in Tier 2 who has a murmur and echocardiographic evidence of myxomatous mitral valve disease should be staged and treated according to the severity of the disease. The echocardiogram provides a snapshot of the heart at a single point in time. The findings should be used to guide the treatment plan and to establish a baseline for future monitoring. The measurements should be recorded in a standardized format, including the left atrial diameter, the left ventricular diameter, the wall thickness, and the ejection fraction. These measurements should be compared to reference values for the species and age of the animal. ### A Record System for Serial Monitoring A standardized record system is essential for the serial monitoring of a patient with a heart murmur. The record should include the following: - The date of the examination - The murmur characteristics, including the grade, location, and quality - The patient's body weight - The clinical signs, if any - The echocardiographic measurements - The treatment plan - The follow-up schedule The record should be updated at each visit. The clinician should compare the current findings to the previous findings to detect any changes. For example, an increase in the left atrial-to-aortic root ratio may indicate progression of the disease and may warrant a change in the treatment plan. ### Troubleshooting Common Challenges There are several common challenges in the evaluation of a heart murmur. The following troubleshooting guide addresses some of these challenges. **Challenge 1: The murmur is present but the echocardiogram is normal.** A normal echocardiogram does not exclude all cardiac disease. The murmur may be physiologic, or it may be associated with a subtle lesion that is not detected on the study. The clinician should consider the possibility of a dynamic lesion, such as a dynamic right ventricular outflow tract obstruction, which may be intermittent. The clinician should also consider the possibility of a non-cardiac cause of the murmur, such as anemia or fever. **Challenge 2: The murmur is absent but the patient has clinical signs of heart disease.** A murmur is not always present in a patient with heart disease. For example, a cat with hypertrophic cardiomyopathy may have a gallop rhythm or an arrhythmia without a murmur. The clinician should not rely on the presence of a murmur to decide whether to perform echocardiography. The clinical signs and the results of other diagnostic tests should be considered. **Challenge 3: The echocardiographic findings are borderline.** The echocardiographic measurements may be borderline, meaning that they are at the upper limit of the reference range. In these cases, the clinician should interpret the findings in the context of the clinical signs and the breed of the patient. A borderline left atrial diameter may be significant in a patient with a murmur and a cough, but it may be less significant in an asymptomatic patient. **Challenge 4: The patient is uncooperative for the echocardiogram.** The echocardiogram requires the patient to be restrained. Some patients are anxious or uncooperative, and the quality of the images may be poor. The clinician may need to use sedation to obtain a diagnostic study. The risks and benefits of sedation should be considered, and the clinician should discuss the options with the owner. ### The Role of the Veterinary Cardiologist The veterinary cardiologist is a specialist who has advanced training in the diagnosis and treatment of heart disease. The cardiologist can provide a comprehensive echocardiographic study, interpret the findings in the context of the clinical picture, and develop a treatment plan. The cardiologist can also perform advanced procedures, such as a transesophageal echocardiogram or a cardiac catheterization. The clinician should consider referral to a cardiologist in the following situations: - The murmur is complex or the echocardiographic findings are uncertain - The patient is not responding to treatment - The patient is a candidate for surgery or other advanced procedures - The patient has a congenital heart defect that may require intervention The World Organisation for Animal Health provides official guidance on animal health and welfare, and the American Veterinary Medical Association provides resources for pet owners. The welfare of the animal should be a primary consideration in all decisions. ### The Role of the Owner in the Decision Process The owner is an important partner in the decision process. The clinician should explain the murmur, the potential causes, and the recommended plan. The owner should be educated on the signs of heart disease and the importance of regular recheck examinations. The owner should also be informed of the costs and the risks of the diagnostic tests. The American Veterinary Medical Association provides resources for pet owners, including information on preventive care and the importance of regular veterinary visits. The American Animal Hospital Association provides similar resources for companion-animal practice. The clinician should use these resources to support the owner education. ### A Practical Example of the Framework in Action A 7-year-old Cavalier King Charles Spaniel is presented for a routine wellness examination. The owner reports that the dog is otherwise healthy and has no clinical signs. On physical examination, the clinician detects a grade 3 systolic murmur with the point of maximal intensity over the left apex. The pulse is strong and regular, and the mucous membranes are pink. The clinician uses the three-tier triage system. The murmur is grade 3, which is Tier 2. The patient is a Cavalier King Charles Spaniel, which is a breed with a high prevalence of myxomatous mitral valve disease. The clinician recommends echocardiography. The echocardiogram is performed by a veterinary cardiologist. The findings include thickening of the mitral valve leaflets, a moderate mitral regurgitation jet, and a left atrial-to-aortic root ratio of 1.7. The left ventricular diameter is within the normal range. The cardiologist diagnoses the patient with myxomatous mitral valve disease, stage B2. The treatment plan is discussed with the owner. The owner is educated on the disease and the prognosis. The patient is scheduled for a recheck examination in 6 months. The record system is updated with the echocardiographic measurements and the treatment plan. ### The Value of a Structured Approach A structured approach to the evaluation of a heart murmur provides several benefits. It ensures that the clinician considers all of the relevant factors, including the murmur characteristics, the patient's signalment, and the clinical signs. It reduces the risk of missing significant disease. It also ensures that the echocardiography is used appropriately, avoiding unnecessary procedures and the associated costs. The framework is not a substitute for clinical judgment. The clinician should use the framework as a guide and adapt it to the individual patient. The framework should be updated as new evidence becomes available. ### The Limitations of the Framework The framework has limitations. The triage tiers are based on clinical experience and the available evidence, but they are not absolute. The murmur grade is a subjective assessment, and the clinical signs may be subtle. The framework does not replace the need for a thorough physical examination and a detailed history. The framework is also limited by the availability of echocardiography. In some practices, the echocardiography is not available, and the clinician may need to refer the patient to a specialist. The clinician should be aware of the local resources and the referral options. ### The Future of Murmur Evaluation The evaluation of heart murmurs is evolving. New imaging techniques, such as tissue Doppler imaging and speckle tracking, are providing more detailed information about the cardiac function. The use of biomarkers, such as the N-terminal pro-B-type natriuretic peptide, is being evaluated for the detection of cardiac disease. These tools may improve the accuracy of the diagnosis and the management of the patient. The clinician should stay current with the new evidence and the guidelines. The World Small Animal Veterinary Association provides global guidelines for companion-animal clinical practice, and the American Animal Hospital Association provides practice guidance. The clinician should use these resources to support the clinical decision-making. ### The Final Decision The final decision to perform echocardiography is a clinical decision. The clinician should consider the murmur characteristics, the patient's signal, the clinical signs, and the results of other diagnostic tests. The clinician should also consider the owner's concerns and the patient's quality of life. The framework provides a structured approach to the decision. The clinician should use the framework to guide the decision and to document the reasoning. The framework should be used to support the clinical judgment, not to replace it. The goal of the evaluation is to identify the patients who have significant cardiac disease and to provide them with the appropriate treatment. The goal is also to avoid unnecessary procedures and to provide the owner with the information they need to make informed decisions. The framework helps the clinician achieve these goals. ## Frequently Asked Questions ### What is the difference between a physiologic and a pathologic heart murmur? A physiologic murmur is a murmur that occurs in the absence of structural heart disease. It is common in young animals and is typically soft, systolic, and localized. A pathologic murmur is a murmur that is associated with structural heart disease, such as valvular disease or a congenital defect. ### How is a heart murmur graded? A heart murmur is graded on a scale of 1 to 6, based on its intensity. A grade 1 murmur is very soft and is only heard with careful auscultation. A grade 6 murmur is very loud and can be heard with the stethoscope off the chest. ### What is the difference between a systolic and a diastolic murmur? A systolic murmur occurs during the systolic phase of the cardiac cycle, when the heart is contracting. A diastolic murmur occurs during the diastolic phase, when the heart is relaxing. Systolic murmurs are more common than diastolic murmurs. ### What is the role of echocardiography in the diagnosis of heart murmurs? Echocardiography is used to characterize the murmur and to identify the underlying cause. It provides information about the structure and function of the heart, which cannot be obtained from auscultation alone. ### What is the treatment for a heart murmur? The treatment for a heart murmur depends on the underlying cause. If the murmur is physiologic, no treatment is needed. If the murmur is associated with heart disease, the treatment may include medication, lifestyle changes, or surgery. ### What is the prognosis for an animal with a heart murmur? The prognosis for an animal with a heart murmur depends on the underlying cause. If the murmur is physiologic, the prognosis is excellent. If the murmur is associated with heart disease, the prognosis depends on the severity of the disease and the response to treatment. ### When should I recheck a heart murmur? The recheck schedule for a heart murmur depends on the underlying cause. If the murmur is physiologic, the recheck may be scheduled in a few months. If the murmur is associated with heart disease, the recheck may be scheduled more frequently. ### What is the role of the veterinary cardiologist? A veterinary cardiologist is a veterinarian who has specialized training in the diagnosis and treatment of heart disease. The cardiologist may be consulted for the evaluation of a complex murmur or for the management of a patient with heart disease. ## Using the Evidence | Source | Best use in this topic | Important limitation | |---|---|---| | [Pet Care](https://www.avma.org/resources-tools/pet-owners) | official guidance | Check the linked page for current local requirements | | [AAHA Guidelines](https://www.aaha.org/resources) | official guidance | Check the linked page for current local requirements | | [Global Guidelines](https://wsava.org/global-guidelines) | official guidance | Check the linked page for current local requirements | ## Related Veterinary Guides - [Leukogram Patterns in Dogs and Cats: A Diagnostic Guide](/knowledge/veterinary-medicine/clinical-pathology/leukogram-patterns-dogs-cats) - [Diagnostic Approach to Acute Abdomen in Dogs and Cats](/knowledge/veterinary-medicine/veterinary-surgery/diagnostic-approach-acute-abdomen-dogs-cats) - [Monitoring Cardiac Biomarkers in Heart Failure Management](/knowledge/veterinary-medicine/clinical-pathology/monitoring-cardiac-biomarkers-heart-failure-management) - [Canine and Feline Chronic Diarrhea: Diagnostic and Therapeutic Framework](/knowledge/veterinary-medicine/clinical-internal-medicine/canine-feline-chronic-diarrhea-diagnostic-therapeutic) - [Echocardiography in Dogs and Cats: Indications and Basic Interpretation](/knowledge/veterinary-medicine/diagnostic-imaging/echocardiography-dogs-cats-indications-basic-interpretation) ## References and Further Reading - [Pet Care](https://www.avma.org/resources-tools/pet-owners). American Veterinary Medical Association. - [AAHA Guidelines](https://www.aaha.org/resources). American Animal Hospital Association. - [Global Guidelines](https://wsava.org/global-guidelines). World Small Animal Veterinary Association. - [Merck Veterinary Manual](https://www.merckvetmanual.com/). Merck Veterinary Manual. - [Cornell University College of Veterinary Medicine](https://www.vet.cornell.edu/). Cornell University. - [Animal Health and Welfare](https://www.woah.org/en/what-we-do/animal-health-and-welfare). World Organisation for Animal Health. - [The Feline Cardiomyopathies: 2. Hypertrophic cardiomyopathy.](https://pubmed.ncbi.nlm.nih.gov/34693811). Journal of feline medicine and surgery, 2021. - [The Feline Cardiomyopathies: 1. General concepts.](https://pubmed.ncbi.nlm.nih.gov/34693806). Journal of feline medicine and surgery, 2021. - [Cardiomyopathy prevalence in 780 apparently healthy cats in rehoming centres (the CatScan study).](https://pubmed.ncbi.nlm.nih.gov/26776583). Journal of veterinary cardiology : the official journal of the European Society of Veterinary Cardiology, 2015. - [Recommendations for management of equine athletes with cardiovascular abnormalities.](https://pubmed.ncbi.nlm.nih.gov/24628586). Journal of veterinary internal medicine, 2014. - [Retrospective evaluation of hypertrophic cardiomyopathy in 68 dogs.](https://pubmed.ncbi.nlm.nih.gov/35322461). Journal of veterinary internal medicine, 2022. > This article is educational and is not a substitute for veterinary diagnosis or treatment. Contact a veterinarian for advice about an individual animal.