The anterograde tarsal venography enhances vessel visualization compared to the retrograde approach in horses

The objective of this study was to compare the number of vessels of the proximal venous access (ramus cranialis of vena saphena medialis) and the distal venous access (vena digitalis dorsalis communis II) for venography and, consequently, intravenous regional limb perfusion of the tarsal region. Seven horses underwent venographic examination of both hind limbs, divided into two groups: proximal venous access (PG) and distal venous access (DG). Rubber tourniquets were applied to the middle third of the tibia and the proximal third of the III metatarsal bone. Thirty mL of contrast was injected (Ioversol 68%), and sequential radiographs in different projections were taken immediately. For the assessment of vascular filling, the venography image was divided into 3 zones using three transversal lines: at the tibial epiphysis, proximal intertarsal joint and the tarsometatarsal joint. All vessels crossing the demarcated lines were counted. Additionally, qualitative observations related to the procedure and venographic findings were recorded. The number of veins observed was higher in the DG when compared with PG (P < 0.0001). In all radiographic projections of the DG, the number of vessels was significantly higher when compared to the PG. Significant differences between the groups were found in the tarsometatarsal joint region (P = 0.0005) and proximal intertarsal joint (P = 0.002). The DG demonstrated a significantly higher vessel count compared with PG, promoting better vascular filling in the tarsal venography of healthy horses. Thus, access to the vena digitalis dorsalis communis II is better indicated for venography and regional limb perfusion in the tarsal region.