Transrectal ultrasonographic examination of the sacroiliac joints of the horse: Abnormal findings and lesions
Authors: Tallaj A., Coudry V., Denoix J.‐M.
Journal: Equine Veterinary Education
Summary
# Transrectal Ultrasonographic Examination of Sacroiliac Joint Disease in Horses The sacroiliac joint's deep anatomical position and ventral lesion distribution present a diagnostic challenge using conventional imaging; transrectal ultrasonography circumvents these limitations by providing direct visualisation of the ventral articulation and supporting ligamentous structures where osteoarthrotic changes predominantly occur. Tallaj and colleagues evaluated abnormal ultrasonographic findings in sacroiliac pathology and proposed a four-point grading system based on articular margin morphology and ventral sacroiliac ligament architecture, emphasising the critical importance of bilateral comparison to identify asymmetrical disease. The classification system stratifies lesion severity from grade 1 through 4, allowing practitioners to standardise descriptions of osteophyte formation, joint space irregularities, and ligamentous changes. For practitioners managing horses with hindlimb lameness, poor performance, or clinical signs suggestive of sacroiliac involvement—particularly where radiography and conventional ultrasound have proven inconclusive—transrectal ultrasonography offers a valuable diagnostic tool; however, imaging findings must always be integrated with gait analysis, palpation findings, and response to diagnostic anaesthesia to avoid over-diagnosing incidental lesions in asymptomatic horses. This work provides the methodological framework necessary for consistent, comparative assessment of sacroiliac disease and should be adopted as part of a comprehensive lameness investigation protocol.
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Practical Takeaways
- •Consider transrectal ultrasonography as a primary imaging tool when sacroiliac joint pathology is suspected, particularly when conventional imaging has limitations
- •Always compare both sacroiliac joints during examination to identify unilateral changes that may be clinically relevant
- •Use the 4-point grading system to standardize lesion documentation and track progression over time for affected horses
Key Findings
- •Transrectal ultrasonography effectively visualizes ventral sacroiliac joint lesions that are difficult to assess with other imaging modalities due to deep anatomical location
- •A 4-point grading system based on articular margin shape and ventral sacroiliac ligament architecture enables standardized classification of osteoarthrosis severity
- •Bilateral comparison of sacroiliac joints is essential for accurate ultrasonographic assessment
- •Ultrasonographic findings must be correlated with clinical signs to establish clinical significance