What are the current treatment options for navicular syndrome in horses beyond corrective shoeing?

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Beyond corrective shoeing, the primary medical treatments for navicular syndrome are bisphosphonates (clodronate disodium or tiludronate), intra-synovial corticosteroid and hyaluronate injections, and extracorporeal shock wave therapy (ESWT), with emerging interest in orthobiologic approaches. Clodronate disodium (Osphos) is the only FDA-approved bisphosphonate with a labeled dose for navicular syndrome in horses. A single dose of 1.4 mg/kg IM (maximum 900 mg/horse) achieves a treatment success rate of 74.7% at day 56 post-treatment, defined as ≥1 AAEP grade improvement in the primarily affected limb without worsening of the contralateral forelimb, compared to 3.3% in saline controls.10 Tiludronate administered via intravenous regional limb perfusion (IVRLP) is an adjunctive bisphosphonate option. It has been evaluated as an adjunct to therapeutic shoeing and distal interphalangeal joint (DIPJ) injections.4 Tiludronate administered by either systemic or IVRLP routes produced no adverse reactions related to colic or renal disease during a 7-day post-administration monitoring period.6 Bisphosphonates are thought to slow excessive bone resorption, which is a central feature of navicular syndrome's progressive degenerative course.6 Intra-synovial corticosteroid and hyaluronate injection — targeting the navicular bursa, DIPJ, or digital flexor tendon sheath (DFTS) — is a mainstay of medical management. Corticosteroids have positive clinical effects in horses with osteoarthritic lameness for up to 70 days after intra-articular injection.4 Triamcinolone acetonide diffuses readily from the DIPJ into the adjacent navicular bursa in horses, supporting DIPJ injection as a route to treat both structures simultaneously.4 Methylprednisolone acetate (100 mg) combined with sodium hyaluronate (20 mg) injected into the DFTS is used when deep digital flexor tendon (DDFT) injury extends proximally beyond the navicular bursa.12 Navicular bursa injection outcomes are strongly influenced