Steroid diffusion into the navicular bursa occurs in horses affected by palmar foot pain.
Authors: Manfredi J M, Boyce M, Malone E D, Anderson C, Anderson L B, Trumble T N
Journal: The Veterinary record
Summary
# Editorial Summary Intra-articular corticosteroid injections into the distal interphalangeal joint represent a cornerstone treatment for palmar foot pain, yet their efficacy has rested partly on the assumption that triamcinolone acetonide (TA) successfully diffuses from the joint into the adjacent navicular bursa and surrounding soft tissues. Manfredi and colleagues investigated this mechanism directly by injecting 10 mg TA bilaterally into the DIPJs of nine horses with palmar foot pain and measuring steroid concentrations in navicular bursa fluid at six hours post-injection using highly sensitive HPLC-MS/MS analysis, with a contralateral hind limb serving as systemic control. The steroid did indeed penetrate the navicular bursa, with affected forelimb concentrations approximately 130 times higher than systemic levels (mean log(10) 3.20 versus 1.89), confirming the therapeutic rationale for this injection route; however, horses with moderate to severe radiographic changes (grade >2) showed markedly reduced bursal penetration, with a fourfold increase in the likelihood of subtherapeutic TA concentrations. These findings suggest that whilst DIPJ injections successfully deliver corticosteroids to the navicular bursa in early-to-moderate palmar foot disease, the diffusion mechanism may be compromised in advanced degenerative cases, potentially explaining variable clinical responses and informing case selection for this intervention.
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Practical Takeaways
- •DIPJ steroid injections do successfully reach the navicular bursa in horses with palmar foot pain, supporting current treatment protocols
- •Horses with advanced radiographic changes (grade >2) may require higher steroid doses or alternative treatment approaches, as drug penetration decreases with severity
- •Consider this evidence when counseling clients on prognosis and treatment response expectations for navicular disease cases
Key Findings
- •Triamcinolone acetonide successfully diffused from the DIPJ into the navicular bursa in horses with palmar foot pain, with forelimb bursa concentrations (mean log10 3.20) significantly higher than systemic control (mean log10 1.89, P<0.0001)
- •Horses with radiographic changes graded >2 were four times more likely to have TA concentrations below 3.2 (158.49 ng/ml), indicating decreased steroid penetration with increased radiographic severity
- •The study validates the clinical rationale for injecting steroids into the DIPJ to treat navicular bursa pathology, though efficacy may be compromised in advanced cases