Health Conditions

Heart Murmur Grade

A Roman numeral scale (I–VI) rating the loudness of a heart murmur heard through a stethoscope. Higher grades generally indicate more significant disease, but echocardiography is required to determine clinical severity.

A heart murmur is an abnormal sound produced by turbulent blood flow within or near the heart, audible through a stethoscope between the normal “lub-dub” heart sounds. Murmurs are graded by intensity on a Roman numeral scale from I to VI.

Murmur Grade Scale

GradeIntensityThrill?
I/VIBarely audible; detectable only in quiet conditions with careful focusNo
II/VISoft but readily detectedNo
III/VIModerately loud; easily heardNo
IV/VILoudNo
V/VIVery loud; audible with stethoscope at chest edgeYes (palpable vibration)
VI/VIAudible with stethoscope held slightly off chest wallYes

A thrill is a palpable vibration of the chest wall produced by very turbulent blood flow — present only in grades V and VI.

Timing and Character

Beyond loudness, murmurs are characterized by:

  • Timing: systolic (between lub and dub — most common; occurs with blood ejection or valve regurgitation) vs. diastolic (between dub and lub — less common; indicates aortic or pulmonic regurgitation)
  • Location: the point of maximum intensity on the chest wall provides clues to the valve involved (left apex = mitral; right base = pulmonic; left base = aortic or subaortic)
  • Quality: plateau (constant intensity), crescendo-decrescendo (diamond-shaped), or decrescendo

Clinical Significance

Murmur grade correlates imperfectly with disease severity:

  • Grade I–II murmurs in small breed dogs are often mitral valve disease in early stages or physiologic murmurs (innocent murmurs with no structural disease)
  • Grade III+ murmurs almost always indicate structural cardiac disease warranting echocardiography
  • Grade V–VI murmurs indicate significant disease in virtually all cases

However, Doberman Pinschers with occult DCM may have no murmur at all — auscultation alone is insufficient for DCM screening. For this reason, annual Holter monitoring and echocardiography are recommended for Dobermans regardless of auscultation findings.