Influence of weight bearing and hoof position on Doppler evaluation of lateral palmar digital arteries in healthy horses.

Objective—To describe the pulsed-wave Doppler tracing of the equine lateral palmar digital artery and its modification in relation to standardized changes in posture. Animals—17 healthy Saddlebred horses. Procedures—Pulsed-wave Doppler examinations of left and right lateral palmar digital arteries of the horses were performed. The baseline examination was performed on each forelimb while horses were standing squarely with the body weight equally distributed among the 4 limbs (BED position). For each forelimb, the examination was repeated during 3 standardized modifications of the horse’s posture (non–weightbearing [NWB] position, full weight-bearing [FWB] position, and a position involving hyperextension of the distal interphalangeal joint [HE position]). In each position, mean values of systolic peak velocity, first and second diastolic peak velocity, end-diastolic velocity, mean velocity, and resistive index were calculated. Data obtained in each different posture were compared statistically. Results—No significant differences in blood flow variables were detected between the left and right forelimbs. However, significant differences were detected in values of first diastolic velocity, second diastolic velocity, mean velocity, and resistive index between the NWB position and FWB position. Also, end-diastolic velocity in the NWB position was significantly different from that recorded in the HE position. Conclusions and Clinical Relevance—The pulsedwave Doppler tracing of the equine lateral palmar digital artery was modified considerably with changes in posture. This suggests that the use of a precisely standardized posture for horses is required to obtain repeatable data.