A 4-year-old Belgian Warmblood mare was presented because of fever, exercise intolerance, aloud diastolic cardiac murmur and a remarkable bounding pulsation that was palpable all over thebody. This bounding pulsation appeared simultaneous with the cardiac contractions. Cardiacultrasound revealed a vegetation on the aortic valve with severe aortic regurgitation and a secondvegetation at the sinus of Valsalva. A reverse flow in the common carotid artery was present duringdiastole. Left heart catheterization showed left ventricular and aortic pressure curves characteristicof a rather acute development of the lesion. The strong bounding pulsation was caused by severeaortic regurgitation that resulted in a very wide pulse pressure with the occurrence of “Watson’swater hammer pulse”. Due to the grave prognosis, treatment was not attempted. Necropsy confirmedaortic valve endocarditis.