Clinical significance of ossification of the cartilages of the front feet based on nuclear bone scintigraphy, radiography and lameness examinations in 21 Finnhorses.
Authors: Ruohoniemi, Mäkelä, Eskonen
Journal: Equine veterinary journal
Summary
Ossification of the cartilages (sidebones) occurs frequently in horses yet remains poorly understood clinically, with previous literature offering conflicting guidance on when these lesions warrant concern. Ruohoniemi and colleagues retrospectively examined 36 front feet in 21 Finnhorses (age ≥4 years) using nuclear bone scintigraphy, radiography and lameness evaluation to establish relationships between radiopharmaceutical uptake patterns, radiographic morphology and clinical signs. Notably, simple height of ossification did not correlate with bone uptake, nor did clearly separate ossification centres; however, intense radiopharmaceutical uptake combined with irregular, widened radiographic appearance of the ossified cartilage proved diagnostically significant—particularly when incomplete fusion lines or bony protrusions were evident. Of the four horses showing intense unilateral uptake, two responded to palmar digital nerve blocks whilst two exhibited subtle gait abnormalities at speed rather than overt lameness, suggesting subclinical effects on performance. For practitioners involved in lameness investigation or prepurchase assessment, this work indicates that ossification of the cartilages merits clinical attention only when scintigraphic and radiographic findings diverge from the individual's other front feet, making multimodal imaging interpretation essential rather than radiographic appearance alone.
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Practical Takeaways
- •Nuclear scintigraphy with unusual radiographic appearance (wider, irregular ossification) is a reliable indicator of clinically significant sidebone in lameness and prepurchase examinations
- •Incomplete fusion lines on radiographs between separate ossification centres and the base are a red flag for potential clinical problems, particularly in lateral heels
- •Many horses with ossification of the cartilages show obscure gait irregularities rather than obvious lameness—look for stiffness and high-speed gait deterioration, especially in coldblooded breeds
Key Findings
- •No significant relationship existed between height of ossifications and radiopharmaceutical uptake at the heels in 36 front feet examined
- •Intense radiopharmaceutical uptake was present unilaterally in 4 horses, with 2 showing relief from palmar digital nerve block and 2 having historical stiffness or high-speed locomotion problems
- •Incomplete fusion lines between separate ossification centres and the base were present in 2 of 4 horses with intense uptake, suggesting clinical significance
- •Increased radiopharmaceutical uptake combined with wider and more irregular radiographic appearance compared to other ossifications in the individual horse was conclusive for clinical significance; obscure locomotion problems were more common than true lameness