Hearing that your veterinarian detected a heart murmur can be alarming, especially when it's followed by talk of chest X-rays and echocardiograms. The good news is that these two tests work together, not against each other, and understanding what each one actually shows can make the next steps feel much less overwhelming.
A heart murmur is simply an abnormal sound created by turbulent blood flow through the heart. It's a finding, not a diagnosis. Murmurs can range from insignificant to a sign of meaningful underlying heart disease, and the only way to know which is with further evaluation. That's typically where chest X-rays and echocardiography come in, often alongside a handful of other tests.
Chest X-rays, also called thoracic radiographs, are usually the first imaging step after a murmur is detected, largely because they're available in nearly every veterinary hospital and don't require specialized equipment or training. X-rays give your veterinarian a general sense of heart size and shape, along with a look at the lungs, which is useful since heart disease can sometimes cause fluid buildup in or around the lungs. Several studies have examined how well radiographic measurements correlate with echocardiographic findings of heart enlargement, generally finding X-rays useful for predicting broad patterns of heart enlargement in conditions like myxomatous mitral valve disease, though with real limitations in precision (Poad et al., 2020; Baisan & Vulpe, 2024).
Radiographic scoring systems have also been shown to have meaningful, though imperfect, correlation with echocardiographic measurements when predicting heart enlargement (Levicar et al., 2022). Notably, research has found that interpreting chamber size on X-rays alone has real limitations, and can even lead to falsely identifying right-sided enlargement when the actual problem is severe left-sided enlargement (Huguet et al., 2021). This is exactly why X-rays are considered a screening tool rather than a definitive one.
An echocardiogram is an ultrasound of the heart, and it provides a level of detail that X-rays simply cannot. Rather than a static image of overall heart size, an echocardiogram allows real-time visualization of the heart valves, chamber dimensions, wall thickness, and blood flow patterns. A detailed review of echocardiographic assessment in dilated cardiomyopathy illustrates just how much specific structural and functional information this test can provide, information that guides both diagnosis and treatment decisions (Bonagura & Visser, 2022).
Because of the skill required to acquire and interpret these detailed images accurately, echocardiograms are typically performed by veterinary cardiologists or veterinarians with advanced training in cardiac ultrasound, which is also why access to this test is more limited than access to X-rays. Research has also explored whether certain combinations of clinical, radiographic, and EKG findings can predict clinically important heart disease without an echocardiogram, underscoring both how valuable echocardiography is and how much veterinarians rely on combining information when it isn't immediately available (Wesselowski et al., 2022).
Because X-rays and echocardiograms measure different things, using one instead of the other means missing part of the picture. X-rays are excellent for a quick, broad assessment and for evaluating the lungs, while echocardiograms provide the specific structural and functional detail needed to characterize exactly what kind of heart disease, if any, is present. Research comparing radiographic and echocardiographic findings across a range of specific conditions, including pulmonary arterial hypertension and patent ductus arteriosus, consistently supports using both modalities as complementary pieces of the same diagnostic puzzle rather than one replacing the other (Adams et al., 2017; Puccinelli et al., 2026).
Beyond imaging, your veterinarian may recommend additional testing to build a more complete picture of your dog's cardiac and overall health:
- An electrocardiogram (EKG) to evaluate the heart's electrical rhythm
- Blood pressure measurement, since hypertension can both cause and worsen heart disease
- Routine bloodwork to assess overall organ function and rule out other contributing conditions
None of these tests replace imaging, but together they give your veterinarian a more complete understanding of your dog's cardiovascular health.
The significance of a new murmur can depend heavily on your dog's age. In puppies, a murmur may indicate a congenital heart defect, a structural abnormality present from birth, and research has specifically examined how these murmurs are identified and managed in young, recently acquired puppies (Pugliese et al., 2021). A survey of veterinarians' approaches to managing incidentally detected murmurs in puppies found real variation in how these cases are handled and referred, which is part of why early, thorough evaluation matters (van Staveren et al., 2024).
Research on the timing of referral to veterinary cardiology specialists for murmur investigation in puppies further highlights how important prompt evaluation can be for congenital conditions (Rovroy & Szatmári, 2021). In contrast, murmurs detected in middle-aged and older dogs are more commonly associated with acquired conditions, such as degenerative valve disease, that develop over time rather than being present from birth.
Regardless of your dog's age, a newly detected murmur generally warrants a thoughtful, structured evaluation rather than a wait-and-see approach. Guidelines on managing incidentally detected heart murmurs in dogs and cats emphasize a stepwise approach, starting with a thorough history and physical exam and escalating to imaging and specialist referral as needed, tailored to the individual patient (Côté et al., 2015).
If your veterinarian recommends an echocardiogram or referral to a cardiology specialist, having quick access to the right expertise matters. Vetmodo makes it easy to find local veterinary cardiologists and specialists who can perform advanced cardiac testing and help you understand exactly what your dog's murmur means. Search Vetmodo today to find a cardiologist near you.
