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

Overview

• This study compared two methods of venous access for imaging and regional drug delivery in horse tarsal (ankle) vessels.
• The distal venous access approach showed better visualization and more vessels filled than the proximal approach, suggesting it is the superior method.

Background and Objective

• The research aimed to evaluate and compare two venous access points in horses for intravenous regional limb perfusion (IRLP) of the tarsal region: a proximal access (ramus cranialis of vena saphena medialis) and a distal access (vena digitalis dorsalis communis II).
• IRLP is used clinically to treat infections or deliver medication directly to a limb, so clear visualization of veins and good perfusion capacity is critical.
• The study sought to determine which site provides better vessel visualization by venography (imaging of blood vessels after injecting contrast). This also relates to efficacy of drug delivery via that site.

Methods

• Subjects: Seven healthy horses were used.
• Each horse’s both hind limbs were examined using two different venous access sites:
• Proximal Group (PG): Ramus cranialis of vena saphena medialis.
• Distal Group (DG): Vena digitalis dorsalis communis II.
• Rubber tourniquets were applied to restrict blood flow, placed at the middle third of the tibia and proximal third of the III metatarsal bone to isolate the region.
• Contrast agent (30 mL of 68% Ioversol) was injected through these veins to visualize vessel filling on radiographs.
• The venography images were divided into three zones based on anatomical landmarks:
• Tibial epiphysis
• Proximal intertarsal joint
• Tarsometatarsal joint
• The number of veins crossing these predefined transverse lines was counted for each access method.
• Qualitative observations regarding the procedure and venographic appearances were also recorded.

Results

• The distal venous access (DG) showed a significantly higher number of visible vessels compared to the proximal access (PG) (P < 0.0001).
• Across all radiographic projections, DG consistently demonstrated more vessels and better vessel filling than PG.
• Statistically significant differences were particularly evident in:
• Tarsometatarsal joint (P = 0.0005)
• Proximal intertarsal joint (P = 0.002)
• These findings indicate better contrast distribution and venous filling with the distal approach.
• No adverse procedural findings were reported, indicating both techniques are feasible, but distal access provides superior imaging quality.

Conclusions and Clinical Significance

• The study clearly supports the use of the vena digitalis dorsalis communis II (distal access) over the ramus cranialis of vena saphena medialis (proximal access) for venography in the horse tarsal region.
• Enhanced visualization of vessels translates to improved intravenous regional limb perfusion capabilities, which is critical for effective localized drug delivery.
• Veterinarians performing tarsal vessel imaging or administering regional perfusion should prefer distal venous access for better diagnostic and therapeutic outcomes.
• This information can guide clinical decisions on optimizing procedures involving the tarsal veins in horses, improving treatment of limb conditions requiring targeted perfusion.