Your Dog Has a Heart Murmur? Here's What You Need to Know.

Two of my older dogs have heart murmurs that, while noted by the vet during each visit, have not required a serious intervention. That said, I’m also careful to keep their diet healthy, ensure exercise is moderate, and I watch for signs of fatigue or panting that tell me it’s time for a rest and cool drink.

What Exactly Is a Heart Murmur?

Let’s go back to your grade 12 biology. The heart is made up of four chambers: the left and right atrium plus the left and right ventricles. As the blood moves through the heart, valves open and close between these chambers to facilitate a steady flow. This prevents it from receding into the previous chamber. Is it all coming back to you?

When your vet checks your dog’s heart with a stethoscope, they’re listening for a sort of lub-dub type of beat that tells them the blood is flowing in a normal manner. With a murmur, the flow is abnormal, and your vet will pick up a whooshing sound rather than a regular heartbeat.

And like any condition, it can be classified into grades that range from 1 through 6, denoting “not overly serious” (grade 1) to “severe or advanced” (grade 6).

Specifically, they read as follows:

Grade I: Barely audible with a stethoscope. Least severe.

Grade II: More easily heard with a stethoscope.

Grade III: Can definitely be detected with a stethoscope on one side of the dog’s chest.

Grade IV: As above, but now audible on both sides of the dog’s chest.

Grade V: Is both loud and presents a vibration.

Grade VI: Both the vibration and sound can be heard without the use of a stethoscope. Most severe.

Beyond the Stethoscope: What to Watch For:

When you’re not sure whether your dog’s heartbeat sounds normal or problematic, some other signs are easier to spot and may indicate a murmur. They include:

• Heavy breathing – even when at rest.
• Inability to walk or exercise for even short periods of time.
• Coughing.
• Weight loss
• Poor oral health.
• Pale or blue gums indicating lack of oxygen

Diagnosis and Treatment

Once an irregular-sounding heartbeat has been detected, your vet will initially recommend bloodwork to identify potential causes such as hypothyroidism, heartworm disease or anemia, which can be treated with medications. If the bloodwork is inconclusive, they may want to take a deeper dive by having your dog undergo an ECG (Electrocardiogram) to understand what’s causing the irregular heartbeat and/or an Echocardiogram to help identify the exact location of the murmur.

Together, these steps will help diagnose the underlying cause of the murmur and ultimately determine the best course of action. In advanced stages, your pet may be put on medications such as Diuretics that help their kidneys flush excess water from their body, improving blood flow. Or, something like Benazepril opens blood vessels and decreases fluid retention to help blood flow more smoothly.

The upside is that steps can be taken to help improve your pet’s quality of life, regardless of the Grade of murmur they’re experiencing. But including your vet in an accurate diagnosis is the first step.