Penile and preputial tumours in the horse: Literature review and proposal of a standardised approach

Abstract

Penile and preputial tumours are not uncommon in the horse, but can cause discomfort and lead to serious complications. Several types of tumour of the male external genitalia have been described. The most common type is the squamous cell carcinoma (SCC), which is found mainly in older horses. Reports of a breed predilection for penile tumour formation are equivocal, but castration, coat colour, poor hygiene and various infectious agents have all been suggested to predispose to the development of some types of tumour (e.g. SCC, papilloma and melanoma). Careful assessment of the primary tumour is an important first step in the design of an optimal treatment protocol. Invasiveness, differentiation grade, tumour size and presence of metastases are all relevant to the decision to pursue additional diagnostic procedures or specific treatment options. To date, no standard protocol has been reported for the approach to penile tumours in the horse and treatments range from minimally invasive therapies (e.g. topical use of 5-fluorouracil) to radical surgical interventions (e.g. en bloc penile and preputial resection with penile retroversion). Completeness of removal of the neoplasm and therefore risk of recurrence is highly dependent on the type of therapy chosen. However, the size and histopathological features of the primary tumour are also important factors with respect to the likelihood of recurrence. This review describes the most common penile and preputial neoplasms in the horse, and outlines a standard protocol aimed at arriving at a specific diagnosis and tailoring the therapeutic approach accordingly.

Diagnosis and surgical treatment of a chronic Staphylococcus aureus infection (botryomycosis) as a long-term complication after castration – a case report

“…However, similar lesions can be observed in neoplastic processes, such as malignant melanoma, fibrosarcoma or squamous cell carcinoma (Seltenhammer et al 2003, Van Den Top et al 2010, Phillips and Lembcke 2013. Although the penis was without pathological findings at clinical examination, neoplasms have to be considered as a differential diagnosis, which has to be excluded by histopathology.…”

Surgical resection of a squamous cell carcinoma in the perianal region of a 25‐year‐old crossbred American Paint gelding using sharp surgical excision, laser excision and chemotherapy

“…; Montgomery ; Hollis ) but is infrequently used due to the necessity for special equipment and concerns regarding management of patients receiving radiotherapy (Van Den Top et al . ; Hollis ). This technique was not available for the current case and would have been cost‐prohibitive.…”

Skin Diseases in Horses

“…35 Treatment A standardized approach to the assessment and treatment of penile tumors has been suggested. 36 This approach is based on evaluation of the primary tumor site with histopathology and ultrasonography and evaluation for possible metastatic disease. Complete surgical excision of the tumor should be curative in the absence of metastatic disease.…”