Evaluation of doppler indexes of the lateral palmar digital artery in lame sport horses

Although lateral palmar digital artery (LPDA) flow velocity does not differ between forelimbs, horses with lameness typically reduce loading of the affected limb during the weight-bearing phase. This study aimed to assess whether Pulsed-Wave (PW) Doppler indices of the (LPDA) blood flow differ between the two forelimbs in horses with unilateral forelimb lameness, and whether these differences correlate with lameness severity. Twenty-seven lame and 15 healthy horses were enrolled. All Doppler ultrasonographic examinations were performed by a single operator, blinded to both the presence or absence of lameness and its location, with horses non-sedated and standing squarely. Peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistive index (RI) of the LPDA in both front limbs were acquired. No significative differences were found between the EDV and RI in the lame group and the sound group. PSV was higher (P = 0.024) in lame group (32.9–123.5 cm/s) compared to the sound group (17.4–69.3 cm/s). Furthermore, considering the differences (Δ) between the lame and sound limbs, ΔPSV was significantly higher (P = 0.002) in lame horses (15.3 cm/s; range 3.7–78.3 cm/s) compared to sound horses (2.1 cm/s; range 0.53–7.4 cm/s). No correlation between Doppler indexes and the degree of lameness was found. Reduced load on affected limbs may increase PSV values in lame limbs in most, though not all horses, thereby widening the difference between the PSV of lame and sound limbs. However, PSV values do not appear to reliably reflect lameness severity. Further research could identify additional factors influencing LPDA, beyond reduced weight bearing.