Penile and preputial tumours in the horse: a retrospective study of 114 affected horses.
Authors: van den Top J G B, de Heer N, Klein W R, Ensink J M
Journal: Equine veterinary journal
Summary
# Editorial Summary: Penile and Preputial Tumours in the Horse Penile and preputial neoplasms occur with greater frequency in horses than other domestic species, yet comprehensive epidemiological data have been limited. Van den Top and colleagues conducted a retrospective analysis of 114 horses presenting with external genital tumours, documenting clinical presentation, histopathological classification, metastatic status, and diagnostic utility of imaging. Squamous cell carcinoma predominated (accounting for the majority of cases), followed by papillomas and melanomas, with affected horses averaging 19.5 years of age and no clear breed predisposition. Critically, poorly differentiated squamous cell carcinomas demonstrated significantly higher rates of regional lymph node metastasis compared to well-differentiated variants, whilst thoracic radiography proved of limited diagnostic value in detecting pulmonary involvement. For equine practitioners, these findings underscore the importance of histopathological grading in prognostic assessment, the necessity of palpating and potentially sampling regional lymph nodes regardless of enlargement, and reinforce that age-related risk warrants vigilant examination of older geldings and stallions presenting with penile discharge, masses or integumentary irregularities of the external genitalia.
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Practical Takeaways
- •Penile and preputial masses in older horses (mean age 19.5 years) should be investigated promptly as squamous cell carcinoma is the most likely diagnosis; histopathology and lymph node evaluation are essential for prognosis
- •Differentiation grade of squamous cell carcinomas is critical for predicting regional lymph node metastasis risk and guiding treatment decisions
- •Regional lymph node examination and biopsy should be performed even when nodes are not palpably enlarged, as pathology assessment is diagnostically valuable; thoracic radiographs are not recommended for routine screening
Key Findings
- •Squamous cell carcinoma was the most prevalent neoplasm affecting 114 horses with penile and preputial tumours, followed by papillomas and melanomas
- •Mean age of affected horses was 19.5 years with no apparent breed predilection
- •Poorly differentiated squamous cell carcinomas had higher tendency to metastasise to regional lymph nodes compared to well-differentiated tumours
- •Thoracic radiography had little value for detecting lung metastases in horses with penile/preputial neoplasms