The murmur associated with AR is usually characteristic. It is a decrescendo holodiastolic murmur, with a PMI over the aortic valve region at the heart base, radiating down to the apex (Figure 6.3). The murmur may also be heard on the right side of the chest at a lower intensity. AR can be difficult to hear in mild cases, where it may be a faint, sighing grade 1/6 murmur. However, in other cases it can be musical, or harsh and rasping and in some animals it is extremely loud, up to grade 6/6 in intensity. It is important to listen carefully with both the diaphragm and the bell of the stethoscope so that sounds of high and low pitch can be heard. It is often helpful to try to ignore systolic sounds and concentrate on diastolic sounds of different pitch over a period of a few minutes.
In some animals, a relatively loud (grade 2-3/6) functional ejection-type murmur is also heard. This may be present because of the large stroke volume of the LV and high velocity of blood flow through the aortic valve which results from severe AR.