A Case Series of Five Horses with Superficial Digital Flexor Tendon Lesions in the Carpal Canal.
Authors: Gates Sophie, Hinnigan Guy, Rich Andrew, Ricci Emanuele, Owen Kathryn
Journal: Journal of equine veterinary science
Summary
Superficial digital flexor tendon (SDFT) injuries within the carpal canal represent a challenging diagnostic and prognostic problem, often characterised by acute unilateral forelimb lameness that intensifies with flexion and subtle clinical signs such as mild palmar swelling. Gates and colleagues examined five horses (aged 11–28 years) presenting with such lesions, using ultrasonography to document increased cross-sectional area and disrupted fibre architecture on longitudinal imaging, findings supported by ulnar nerve anesthesia that abolished lameness in most cases. Only three of the five horses returned to prior performance levels, with two requiring euthanasia; notably, a back-at-the-knee carpal conformation significantly predicted poorer outcomes in this cohort. Histopathological investigation of one euthanased horse revealed an intratendinous fibroma, suggesting that some carpal canal SDFT lesions may have underlying structural abnormalities beyond simple strain injury. For practitioners managing forelimb lameness, this case series underscores the importance of careful ultrasonographic assessment of the carpal canal region—particularly in older horses and those with suboptimal carpal conformation—as these lesions carry substantial prognostic implications and may warrant early intervention or conservative management depending on underlying pathology.
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Practical Takeaways
- •SDFT lesions in the carpal canal present with characteristic acute unilateral lameness worse on flexion—consider this diagnosis in older horses with these signs
- •Ultrasound assessment should include longitudinal views to detect loss of fiber architecture; compare cross-sectional area between limbs as a key diagnostic marker
- •Prognosis is guarded but not hopeless (60% return to work); however, pre-existing back-at-the-knee conformation suggests a poorer outcome—discuss realistic expectations with owners
Key Findings
- •5 horses (ages 11-28 years) presented with acute unilateral forelimb lameness that worsened on proximal limb flexion
- •Ultrasonographic findings showed increased cross-sectional area of SDFT and loss of fiber architecture on longitudinal images
- •3 of 5 horses (60%) returned to previous performance level; 2 were euthanized
- •Back-at-the-knee carpal conformation was associated with poorer prognosis; ulnar nerve anesthesia abolished lameness in cases where performed