Penile and preputial squamous cell carcinoma in the horse: a retrospective study of treatment of 77 affected horses.
Authors: van den Top J G B, de Heer N, Klein W R, Ensink J M
Journal: Equine veterinary journal
Summary
Squamous cell carcinoma represents the most common genital neoplasm in stallions and geldings, yet evidence-based guidance on optimal surgical management has been limited. This retrospective analysis examined 77 horses treated for penile and preputial SCC, comparing outcomes across five surgical approaches (ranging from cryosurgery and simple excision through to en bloc resection with penile retroversion and regional lymphadenectomy) and correlating histopathological tumour grade with recurrence rates and long-term prognosis. Partial phallectomy alone yielded concerning recurrence rates of 25.6%, whereas en bloc resection with retroversion substantially reduced recurrence to 12.5%—a finding that has direct implications for case selection and surgical planning. Critically, poorly differentiated tumours demonstrated significantly higher metastatic potential and treatment failure compared with well-differentiated lesions, indicating that routine histopathological grading should inform both prognosis discussions and the aggressiveness of initial surgical intervention. Overall treatment success achieved 55.7%, highlighting that whilst genital SCC remains a challenging condition, more extensive surgical techniques combined with tumour grade assessment can meaningfully improve outcomes and reduce the burden of recurrent disease in affected horses.
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Practical Takeaways
- •En bloc resection with penile retroversion should be considered over partial phallectomy alone, as it significantly reduces recurrence risk from 25.6% to 12.5%
- •Tumour grading based on histological differentiation is prognostically valuable and should guide surgical planning and inform clients of realistic success rates
- •Early detection and complete surgical removal are critical, as poorly differentiated tumors and those with lymph node involvement carry substantially worse prognoses and higher recurrence rates
Key Findings
- •Overall treatment success rate for penile and preputial SCC was 55.7%, with complete removal and prevention of recurrence as endpoints
- •Partial phallectomy resulted in 25.6% recurrence rate (10/39 cases), substantially higher than en bloc resection with retroversion at 12.5% (1/8 cases)
- •Poorly differentiated SCCs were more likely to metastasize and had poorer treatment outcomes compared to well-differentiated tumors
- •Horses with confirmed inguinal lymph node metastasis had 25.0% recurrence rate (1/4 cases), indicating advanced disease at presentation