A 4-year-old Belgian Warmblood mare was presented because of fever, exercise intolerance, a loud diastolic cardiac murmur and a remarkable bounding pulsation that was palpable all over the body. This bounding pulsation appeared simultaneous with the cardiac contractions. Cardiac ultrasound revealed a vegetation on the aortic valve with severe aortic regurgitation and a second vegetation at the sinus of Valsalva. A reverse flow in the common carotid artery was present during diastole. Left heart catheterization showed left ventricular and aortic pressure curves characteristic of a rather acute development of the lesion. The strong bounding pulsation was caused by severe aortic regurgitation that resulted in a very wide pulse pressure with the occurrence of "Watson's water hammer pulse". Due to the grave prognosis, treatment was not attempted. Necropsy confirmed aortic valve endocarditis
