Dogs. The first time we meet these furever friends, they steal our hearts — which makes it all the more important that we protect theirs.
Routine veterinary visits help ensure our dogs’ bodies and minds are functioning at their best. A veterinarian’s stethoscope is a vital tool — because while changes in the heart, such as murmurs, are impossible to see, they’re often easy to hear.
Listening In: Understanding Heart Murmurs in Dogs
So, what does a healthy canine heartbeat actually sound like?
According to Dr. David MacDonald, DVM, CVA, CVSMT, when it comes to the heartbeat, every veterinarian listens for the traditional lub-dub, lub-dub, lub-dub cadence.
“As the heart is beating, its four chambers have a synchronized motion,” Dr. MacDonald says. “When they’re doing their job, pumping blood through the heart, that sound means the muscle is contracting properly.”
Veterinarians are listening closely for any changes whatsoever.
Heart murmurs in dogs, he says, are the trademark of a turbulent blood flow, commonly accompanied by a “swish, swish, swish” sound.
This swishing murmur does not necessarily correspond to something negative, Dr. MacDonald says. “It simply highlights that there is something different going on.”
A dog experiencing a murmur may just be particularly excited, he notes.
“The heart is beating so quickly, it goes into overdrive. And because the blood is flowing through the chambers at such a rapid pace, this sound is created. And that may be the extent of it.”
However, there are also structural changes within the heart that require closer evaluation.
“There are many conditions that can cause the heart to work overtime at pumping blood through the body,” he explains.
An enlarged heart, for instance, can cause changes to the chambers, altering the dynamic of the blood flow and—subsequently—the sound it makes.
Consistency is the key here.
“If an animal has always had a normal heartbeat, and it’s been normal with each visit, the moment we hear something different, we document the change,” Dr. MacDonald says.
Murmurs are graded on a scale from 1 to 6 based on audibility and intensity, with higher grades sometimes palpable by touching your dog’s chest, indicating more significant changes in heart function.
“It’s almost as if you’ve put your hand on a loudspeaker playing bass,” Dr. MacDonald continues. “You can feel that on the skin’s surface, because the heart is functioning differently.”
Symptoms are paramount, as well. If an animal presents with shortness of breath or fainting, a visit to the emergency center is a must, so that the dog can be monitored around the clock.
Regardless of the grade the murmur receives, veterinarians typically refer dogs with newly discovered murmurs to a specialist.
“Ultimately, you need to see a veterinary cardiologist,” Dr. MacDonald says.
“The heart is their main area of focus,” he adds. “They have a whole host of tools and equipment and ways of measuring that we simply don’t have.”
What the Cardiologist Can Do
Veterinary cardiologists use tools like echocardiograms and ultrasounds to visualize heart structure and function, identify abnormalities, and get to the root cause of a murmur.
“This way, they can see the three-dimensional shape of the heart,” Dr. MacDonald says.
Does that chamber look thickened? Are the valves opening and closing the way they should?
“They can see these things in real time while the patient is awake,” Dr. MacDonald says. “With an ultrasound, they can see how the heart is actually beating and can also measure blood pressure while it’s beating, which helps them determine what may be happening.”
Diagnoses may range from valvular disease — where the heart’s valves don’t seal properly and become leaky — to dilated cardiomyopathy, an enlargement of the heart that severely weakens the muscle. Electrical impulses, too, may be off kilter, says Dr. MacDonald, making it difficult for the heart to coordinate its beat.
“The cardiologist can go from what we see in the exam room to a proper diagnosis,” Dr. MacDonald continues, adding that dogs without symptoms may not require urgent care but should still see a specialist for diagnosis and possible medication. The management of heart conditions can allow many to live normal lifespans with monitoring.
But it all must begin with a visit to the veterinarian.
“This is why we perform these exams and listen carefully to the heart,” Dr. MacDonald says. “It’s an essential part of your pet’s ongoing care. You might not notice any changes at home, but when we listen with our stethoscope, that’s often how we discover, ‘Oh — here’s something different.’”
After all, protecting our dogs’ hearts ultimately means protecting our own, too.
