Torsion of the deep digital flexor tendon in a front limb of four horses

Summary The deep digital flexor tendon (DDFT) plays an essential role in the horse's front limb. Several structures restrict its displacement, but none prevents it from rotating. This case report describes four cases of 180° DDFT torsion in front limbs (one acute, one subacute and two chronic). The suspected underlying mechanism involves trauma during fetlock flexion, followed by distal displacement of the torsion during extension. The horses presented with varying clinical signs, but all showed digital flexor tendon sheath (DFTS) effusion, a palpable cordlike structure in the palmar pastern and a decreased caudal stance phase. Only the acute and subacute cases were lame. Diagnosis could be made by ultrasonography in all cases, although the diagnosis was made by magnetic resonance imaging in one case. Three cases underwent treatment (two surgically and one manually), resulting in persistent correct DDFT positioning and favourable long‐term outcomes (1–9 years). Nonacute cases proved more challenging to treat and required surgical repositioning. In conclusion, although infrequent, DDFT torsion should be considered in horses with unexplained DFTS effusion, a cordlike structure in the palmar pastern and an altered gait. Ultrasonography is sufficient for diagnosis, and prompt treatment can restore normal tendon orientation.