Heart murmur in a dog — is it dangerous?

📍 Veterinary Hospital Sacrum — Cardiac examinations and ultrasound

“Your dog has a murmur in his heart.”

This phrase frightens many owners during a vaccination visit. However, the murmur itself is not a disease, but a finding that tells us that there is a flow in the heart that causes tinnitus.

What is the cause of the murmur?

The murmur arises from the swirling blood flow.

• Puppies: Puppies under 6 months of age may have a so-called physiological (innocent) murmur, which disappears with growth.
• Adults (small dogs): The most common cause is mitral valve degeneration (valve defect). The flap does not close tightly, and blood leaks in the wrong direction.
• Adults (large dogs): May indicate heart muscle disease (DCM) or valve defect.

Murmur intensity (Grades 1—6)

The veterinarian classifies the intensity of the murmur:

• 1—2: Very quiet, can only be heard with close listening.
• 3—4: Clear murmur, heard immediately.
• 5—6: Very strong, it is felt even in the hand as a “buzzing” from the top of the chest.

⚠️ NB: The intensity of the murmur does not always indicate the severity of the disease. Even a quiet murmur can be a sign of a serious defect, and on the other hand, a loud murmur can be asymptomatic for a long time.

When are further examinations needed?

Just listening with a stethoscope doesn't tell why a murmur is heard or how badly the heart is strained.

Therefore, we recommend ultrasound examination of the heart, if:

1. The murmur is intense (3/6 or above).
2. The dog has symptoms (cough, fatigue).
3. This is a puppy with which the murmur does not disappear.
4. This is a breed with a high risk of heart disease (e.g. cavalier, doberman).

Ultrasound is a painless examination that gives accurate information about the state of the heart.

📞 Book an appointment for a heart ultrasound in Vantaa: 010 739 9130