Interphalangeal joint block sites, horse

Interphalangeal joint block sites in a horse. 1. Distal interphalangeal joint: A 22‑gauge, 2.5‑cm (1‑inch) needle is quickly inserted in the direction of the arrow, with the limb bearing weight. Synovial fluid is often visible in the needle hub. 2. Proximal interphalangeal joint: A 20‑ to 22‑gauge, 3.8‑cm (1½‑inch) needle is inserted lateral to the extensor tendon and proximal to the joint margin, in the direction of the arrow and along the dorsal surface of the proximal phalanx, with the limb bearing weight. The distal and proximal interphalangeal joints can also be accessed palmarly; however, these approaches are more challenging.