Table 6.4 Summary: Clinical evaluation of horses with aortic regurgitation

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History

Variable signs noted by owners depending on the severity of the condition:

incidental finding (common)

poor exercise tolerance (uncommon)

left- and/or right-sided congestive heart failure (uncommon)

Sudden onset or progressive over days to years

Clinical findings

Mucous membrane colour usually normal

CRT normal to slow

Arterial pulse may be normal, strong and bounding, or weak

Pulse rate normal to rapid, regular or irregular

Grade 1-6/6 descrescendo holodiastolic murmur with a PMI at the left base

Murmur may radiate ventrally

Murmur may radiate to right side of the chest

Look for signs of endocarditis (very uncommon, but aortic valve is commonest site)

Evaluation of significance

Most likely to be significant if:

associated with poor athletic performance slow CRT

strong, bounding pulse

weak or variable pulse quality (usually only when in CHF) resting heart rate >45 bpm

widespread radiation

associated with MR

associated with abnormal arrhythmia, especially AF

associated with signs of left-sided or right-sided congestive heart failure valve affected by endocarditis

Note: The murmur of AR may be very loud in animals with relatively little volume overload

Helpful diagnostic tests

Echocardiography

Electrocardiography if arrhythmia present

Blood pressure measurement (wide pulse pressure)

Clinical pathology if endocarditis suspected