Chronic Collateral Sesamoidean Desmopathy in Draft Horses: Magnetic Resonance Imaging and Histopathological Findings.
Authors: Abu-Seida Ashraf M, Elemmawy Yahya M
Journal: Journal of equine veterinary science
Summary
# Chronic Collateral Sesamoidean Desmopathy in Draft Horses: MRI and Histopathological Findings Collateral sesamoidean ligament (CSL) desmopathy represents a rarely documented condition in draft horses, yet this eight-case study by Abu-Seida and Elemmawy reveals it may be more significant than previously recognised, affecting the forelimbs exclusively and presenting bilaterally in 62.5% of cases. Using MRI analysis confirmed by histopathological examination, the researchers characterised chronic CSL desmopathy by ligamentous thickening with heterogeneous signal intensities—including multiple foci of low signal interspersed with moderate signal intensity—along with associated pathologies such as deep digital flexor tendon injury and distal sesamoidean impar desmitis. Histological investigation unveiled separated fascicular bundles surrounded by disorganised connective tissue, alongside concerning degenerative changes including cartilaginous metaplasia, mineralisation, and dystrophic calcification within the injured ligament. All affected horses demonstrated consistent clinical findings: positive proximal digital nerve blocks and positive front digital flexion tests, whilst radiography failed to detect osseous abnormalities, underscoring MRI's superiority as a diagnostic tool in such cases. For practitioners managing chronic lameness in draft horses presenting with digital pain, recognition of these MRI hallmarks and understanding that progressive mineralisation and cartilaginous change may occur has important implications for prognosis and the potential trajectory of soft tissue healing.
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Practical Takeaways
- •Suspect CSL desmopathy in draft horses presenting with forelimb lameness, positive digital flexion tests, and positive proximal digital nerve blocks; MRI is essential for diagnosis
- •Monitor for bilateral involvement and concurrent DDFT and impar ligament pathology, as these conditions frequently occur together in chronic cases
- •Chronic CSL desmopathy can progress to cartilaginous metaplasia and dystrophic calcification, indicating poor prognosis if left unmanaged
Key Findings
- •Chronic CSL desmopathy affected forelimbs in 100% of cases and was bilateral in 62.5% of draft horses studied
- •MRI showed ligament thickening with heterogeneous signal intensities and multiple foci of low signal interlaced with moderate signal intensities
- •Histopathology revealed cartilaginous metaplasia, mineralized areas, and dystrophic calcification within injured ligaments
- •CSL desmopathy was concomitant with deep digital flexor tendon injury and distal sesamoidean impar desmitis in chronic cases