Clinical, magnetic resonance, and sonographic imaging findings in horses with proximal plantar metatarsal pain.

This research analyzes the efficacy of sonography and magnetic resonance imaging in diagnosing horse lameness due to proximal plantar metatarsal pain. The study found both have a fair degree of success, but also highlighted certain limitations of each method.

Introduction and Research Objective

• The research retrospectively scrutinizes 39 horses, or 46 separate instances of hind limb lameness attributed to proximal plantar metatarsic pain. It aims to compare and evaluate the performance of two diagnostic imaging techniques, sonography and magnetic resonance (MR) imaging.
• The MR imaging results were treated as a reliable reference point or the ‘clinical gold standard’ to compare the findings from sonography.
• The main objective was to improve the understanding of sonography and MR imaging in diagnosing diseases related to the suspensory ligament in horses’ hind limbs.

Findings and Observations

• Results of MR imaging diagnosis indicated desmopathy (a condition involving ligament disease) of the proximal suspensory ligament in 21 instances, while it recognized proximal plantar metatarsal pain of unknown origin in 12 cases. The test also detected osseous injury (bone damage) at the ligament’s origin in four limbs and a condition unrelated to the suspensory ligament in nine instances.
• Sonography showed sensitivity (ability to correctly identify true positives) of 0.77 and 0.66 respectively for diagnosing the desmopathy condition and properly localizing lesions. It exhibited a specificity (ability to correctly identify true negatives) of 0.33 and 0.31 for the same.
• Changes detected by MR imaging that correlated with desmopathy included signal hyperintensities and an increase in the cross-sectional area when compared to the corresponding part of the healthy hind limb.

Conclusions and Implications

• The study found that local anesthesia of the deep branch of the lateral plantar nerve is not a specific indicator of either the proximal suspensory desmopathy or of proximal plantar metatarsal pain. This is because unrelated conditions to the suspensory ligament and outside of the proximal plantar metatarsal region were also diagnosed.
• The performance of sonography, while reasonable, was found to be imperfect for both diagnosing proximal suspensory desmopathy and accurately localizing lesions.
• MR imaging was identified as a more robust tool for comparing diagnostics as it could differentiate between variations in diseases state and origin.