The Impact of Excision Interval on Equine Melanoma Progression: Time Matters?
Authors: Pimenta José, Prada Justina, Pires Isabel, Cotovio Mário
Journal: Animals : an open access journal from MDPI
Summary
Equine melanomas are prevalent in grey horses, yet veterinary understanding of their temporal progression remains limited, partly because some practitioners have questioned whether early surgical intervention offers genuine benefit over watchful waiting. Pimenta and colleagues examined 42 tumours (13 benign, 29 malignant) from 34 horses, comparing clinical and histological characteristics against the interval between initial detection and surgical excision. Delayed excision had marked consequences: tumours removed later were significantly larger (p = 0.038), horses harbouring melanomas for extended periods developed multiple tumours at higher rates (p = 0.011), and critically, tumours excised after longer intervals were five times more likely to be malignant rather than benign (p = 0.035). These findings challenge the permissive approach to melanoma management and provide quantifiable evidence that early surgical intervention substantially alters disease trajectory. For equine practitioners, this reinforces that recommendations for prompt excision—rather than monitoring asymptomatic melanomas—are grounded in clear biological progression, making early intervention a cornerstone of evidence-based melanoma management in grey horses.
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Practical Takeaways
- •Early surgical excision of equine melanomas is critical—delaying intervention significantly increases malignancy risk and tumor size, contrary to owner/veterinarian beliefs that slow progression justifies watchful waiting
- •Horses with detected melanomas should be monitored closely for additional tumors, as prolonged intervals between detection and treatment correlate with development of multiple lesions
- •This evidence supports recommending prompt surgical intervention when melanomas are first identified in gray horses, rather than adopting a conservative 'slow progression' management approach
Key Findings
- •Tumors excised after longer intervals were significantly larger than those excised sooner (p = 0.038)
- •Longer excision intervals were associated with increased likelihood of malignancy, with delayed excision resulting in 5-fold higher malignancy risk (p = 0.035)
- •Horses carrying tumors for longer periods were significantly more prone to developing multiple tumors (p = 0.011)
- •Of 42 tumors studied, 29 (69%) were malignant and 13 (31%) were benign across 34 horses