Sonographic observations of the peripheral vasculature of the equine thoracic limb

Investigations of the equine peripheral vascular system have been constrain ed by the lack of a non-invasive method of examining the arteries and veins of the limbs of the conscious horse. Precise correlations were established between the gross anatomical features of the peripheral vessels and their B-mode sonographic appearance in each thoracic limb of 35 horses. A sonogra phic imaging protocol was established. Additional Doppler sonographic recor dings defined the arterial waveforms and demonstrated that blood flow to th e foot could be evaluated in the lateral proper digital artery, distal to t he level of the coronary band. Valves (with 2-4 cusps) were identified in t he lumina of the medial and lateral palmar common digital veins and those o f the medial and lateral palmar proper digital veins. Spontaneous echo cont rast, a smoke-like haze of echoic blood, was seen in the lateral and medial palmar common digital veins, the distal deep palmar venous arch and commun icating branches, and the palmar proper digital veins, and occasionally see n in the distal deep palmar arterial arch and distal proper palmar digital arteries. The value of duplex sonography (B-mode and Doppler) for anatomica l and physiological studies of the peripheral vasculature of the horse was clearly established. Such data could be applied to the investigation of dis eases affecting the peripheral circulation.