Lameness in 46 horses associated with deep digital flexor tendonitis in the digit: diagnosis confirmed with magnetic resonance imaging.
Authors: Dyson S, Murray R, Schramme M, Branch M
Journal: Equine veterinary journal
Summary
# Editorial Summary: Deep Digital Flexor Tendonitis as a Cryptic Cause of Foot Lameness Lameness localised to the digit has historically challenged diagnosis when radiographs and ultrasound appear unremarkable, yet MRI reveals substantial pathology; this 2003 study examined 75 lame horses to determine how frequently deep digital flexor tendon (DDFT) injuries explained seemingly unexplained foot pain and to characterise the lesion types involved. The research identified DDFT pathology in 46 horses (61%), subdivided into 32 cases of primary tendonitis and 14 cases where concurrent navicular bone disease contributed significantly to lameness, with lesions distributed across the insertional region, proximal to the navicular bone, or spanning multiple sites. Notably, conventional diagnostic techniques proved insufficient: ultrasonography identified only 2 of 19 proximal lesions visible on MRI, whilst palmar digital nerve analgesia abolished lameness in only 24% of affected horses, suggesting that DDFT pain does not always transmit via the palmar digital nerves alone. Intra-articular DIP joint analgesia provided more reliable relief, improving lameness in 68–92% of horses depending on concurrent pathology, whereas scintigraphy was moderately sensitive (41% detection rate across pool and bone phase images). For practitioners, these findings underscore that negative or inconclusive ultrasound and radiographic results do not exclude DDFT involvement in chronic digit lameness, that response patterns to specific nerve blocks may indicate tissue involvement, and that MRI remains the gold standard for definitive diagnosis when foot pain persists despite conventional investigations.
Read the full abstract on PubMed
Practical Takeaways
- •Negative radiographs do not rule out significant DDFT injuries—consider MRI for horses with persistent digit lameness when standard imaging is unremarkable
- •Palmar digital nerve blocks are unreliable for confirming DDFT as the sole pain source; intra-articular DIP joint analgesia is more useful diagnostically and therapeutically
- •Ultrasonography has poor sensitivity for distal pastern region DDFT lesions; MRI is superior for accurate diagnosis and lesion characterization
Key Findings
- •61% (46/75) of horses with digit pain and normal radiographs had DDFT lesions on MRI that were major contributors to lameness
- •Lameness was abolished by palmar digital analgesia in only 24% (11/46) of horses with DDFT injuries, suggesting other structures are often involved
- •Intra-articular DIP joint analgesia improved lameness in 68% of primary DDFT cases and 92% of cases with concurrent navicular pathology
- •Ultrasonography detected only 2 of 19 lesions extending proximal to the proximal interphalangeal joint, while MRI identified all 19