Hearing that your pet has a heart murmur can feel worrisome, but it’s important to know that a murmur isn’t always a sign of serious heart disease. It’s a clue, not a diagnosis. Understanding heart murmur and anesthesia in pets is an important next step, because what matters most is determining what that sound means for your individual pet and how it may affect future procedures.
What Your Veterinarian Learns from the Physical Exam
When your veterinarian detects a murmur with a stethoscope, they immediately begin gathering important information.
- Grade of the murmur: This describes how loud it is, on a scale of I to VI. A louder murmur isn’t always more serious, but it can guide what to look for next.
- Point of maximal intensity (PMI): This helps localize where the sound is strongest over the mitral, tricuspid, aortic, or pulmonic valves, which can indicate which part of the heart might be affected.
- Lung sounds: Crackles, wheezes, or muffled lung sounds can suggest fluid buildup (pulmonary edema or pleural effusion) or other respiratory concerns related to heart function.
In addition to listening to the heart and lungs, your veterinarian will ask questions about your pet’s life at home:
- Have you noticed coughing, especially at night or after activity?
- Does your pet tire more easily on walks or during play?
- Has your pet ever fainted or suddenly collapsed?
These signs provide valuable context about how the heart is functioning in daily life.
What Thoracic Radiographs (Chest X-rays) Can Tell Us
If a murmur is detected, chest X-rays are often the next step. Radiographs help your veterinarian see the bigger picture:
- Heart size and shape: An enlarged heart can indicate long-term changes in how it’s functioning.
- Specific heart chamber enlargement: For example, the left atrium might be enlarged in cases of mitral valve disease.
- Pulmonary veins and arteries: Enlarged pulmonary veins can point to congestion or fluid backup.
- Pleural effusion: This is fluid around the lungs that may make breathing more difficult.
- Early pulmonary edema: Sometimes, fluid in the lungs is present before a pet shows symptoms. X-rays can catch this early.
This information helps determine whether your pet’s heart murmur is causing secondary changes and whether treatment is needed now or simply close monitoring over time.
What an Echocardiogram (Heart Ultrasound) Reveals
The echocardiogram is the most informative test for understanding what’s behind a heart murmur. It uses ultrasound to visualize the heart’s internal structures and motion in real time.
From an echocardiogram, we can learn:
- The cause of the murmur: Sometimes, a murmur is physiologic—meaning there’s no structural heart disease at all. This is especially true in younger or anxious pets.
- Specific disease type: For example, a leaky valve (mitral or tricuspid regurgitation) versus thickened heart muscle (hypertrophic cardiomyopathy).
- Heart function: We can see how well the heart is contracting, relaxing, and circulating blood.
- Guidance for medication: Certain drugs can be prescribed to improve contractility, control arrhythmias, or reduce fluid buildup, making both daily life and anesthesia safer.
- Anesthetic risk and prognosis: Knowing the exact diagnosis allows us to tailor anesthesia plans and give owners a clearer understanding of what to expect long-term.
Why Understanding Heart Murmur and Anesthesia in Pets Matters
Just like not all heart disease is treated the same way, the anesthetic management of a patient with heart disease will vary based on the type of disease and severity. The goal during anesthesia is always to maintain cardiac output (how much blood the heart pumps each minute) and ensure adequate blood flow to vital organs. However, the specific way these goals are achieved may vary based on the patient’s diagnosis.
- In pets with leaky heart valves (valvular disease), the heart may struggle to pump enough blood forward. Here, we focus on supporting cardiac output, sometimes with medications that improve the strength of contraction or help manage fluid balance.
- In pets with thickened heart muscle (hypertrophic cardiomyopathy), the heart can’t relax and fill properly. In these cases, we aim to avoid tachycardia (very high heart rates) or large increases in heart contractility, which could worsen oxygen delivery.
An accurate diagnosis allows the veterinary team to design an individualized anesthetic plan that prioritizes safety and comfort.
One commonly used approach is a balanced anesthetic technique, where multiple medications are combined to reduce the amount of inhalant gas anesthesia required. For example, an infusion of fentanyl, a short-acting opioid, provides pain relief and sedation, allowing the anesthetist to keep gas levels lower and the heart more stable throughout the procedure.
When Advanced Diagnostics Aren’t Possible
Sometimes, advanced testing like X-rays or echocardiography can’t be performed, whether due to an emergency situation or financial limitations. If this is the case, please know that your veterinary anesthesiologist or veterinarian has managed this clinical scenario many times before and still has a wealth of knowledge about how to keep your pet safe under anesthesia.
Even without full diagnostic imaging, your anesthesiologist will:
- Use balanced anesthesia techniques to minimize stress on the heart.
- Critically evaluate your pet’s overall condition and blood work to assess hydration and fluid balance.
- Monitor the heart rhythm, blood pressure, and oxygenation continuously during anesthesia.
- Choose drugs and fluids that best support your pet’s cardiovascular system.
These steps allow the veterinary team to respond immediately to any changes and maintain stable heart function throughout the procedure.
The Takeaway
A heart murmur is an important finding that deserves attention, but it doesn’t automatically mean your pet is in danger. With advanced diagnostics like X-rays and echocardiography, your veterinary team can determine why the murmur is present, how the heart is functioning, and what it means for heart murmur and anesthesia in pets during any future procedures.
And even when advanced testing isn’t possible, you can take comfort knowing your veterinary anesthesiologist has the skills and tools to keep your pet’s heart and the rest of their body, as safe as possible.
If you have questions or need guidance about your pet’s heart health or upcoming procedure, please contact us. We’re here to support you and help your pet return home safely.
Images used under creative commons license – commercial use (12/02/2025) Photo by Marcin Szmigiel on Unsplash