Spontaneous bilateral superficial digital flexor tendon rupture in a horse with guttural pouch empyema and suspected purpura hemorrhagica
Authors: MacKinnon Kimberly J., Tan Jean‐Yin, Schaal Suzon W., Davies Jennifer L.
Journal: Equine Veterinary Education
Summary
# Editorial Summary An 11-year-old Quarter Horse presenting with urticaria, bilateral hindlimb oedema, and progressive dropped fetlocks was ultimately found at post-mortem to have suffered bilateral spontaneous superficial digital flexor tendon rupture—a previously unreported complication of purpura haemorrhagica. Guttural pouch empyema with confirmed *Streptococcus equi* subspecies *equi* infection triggered an immune-mediated leukocytoclastic vasculitis that affected not only the skin (causing cutaneous infarction) but unexpectedly also damaged the tendon tissue itself, leading to structural failure. Despite combination therapy with enrofloxacin, penicillin, phenylbutazone and dexamethasone, the horse deteriorated and was euthanased; histological examination confirmed vasculitic changes in the superficial digital flexor tendons mirroring those seen in affected skin. This case broadens our understanding of purpura haemorrhagica pathology and highlights the need for increased vigilance during *S. equi* infections, particularly when managing dropped fetlocks or acute hindlimb dysfunction with concurrent vascular signs. Farriers and physiotherapists should be aware that sudden tendon failure in the context of recent streptococcal disease may reflect deep immune-mediated damage rather than mechanical overload alone, fundamentally altering management strategies and prognosis.
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Practical Takeaways
- •Spontaneous tendon rupture should be added to the differential diagnosis list for complications following S. equi infection, even in the absence of direct trauma
- •Horses presenting with acute bilateral hindlimb lameness, dropped fetlocks, and urticaria following streptococcal infection may have vasculitis affecting tendons and should be evaluated carefully before aggressive rehabilitation is attempted
- •Early recognition of purpura hemorrhagica with systemic vasculitis may warrant aggressive anti-inflammatory and immunosuppressive therapy, though prognosis remains guarded when tendon involvement is present
Key Findings
- •First documented case of purpura hemorrhagica with leukocytoclastic vasculitis affecting superficial digital flexor tendons in an equine
- •Bilateral spontaneous SDFT rupture occurred secondary to immune-mediated vasculitis following streptococcal infection
- •Guttural pouch empyema with S. equi subsp. equi confirmed on post-mortem examination with concurrent cutaneous and tendinous vasculitis
- •Despite combined antibiotic, NSAID, and corticosteroid therapy, the horse deteriorated and required euthanasia