Penile and preputial surgery

Disorders of the equine penis and prepuce amenable to surgery include neoplasia, habronemiasis, chronic paraphimosis, and rarely priapism or congenital malformations. Squamous cell carcinoma (SCC) is the most common tumor type affecting the equine male external genitalia in aged horses, mainly affecting unpigmented skin covering the glans and free part of the penis. Most neoplastic lesions involving the glans and free part of the penis necessitate partial phallectomy with or without en bloc resection of the prepuce.¹ Particularly SCC are malignant tumors with a locally aggressive growth behavior, and (depending on the stage at presentation) usually require more aggressive forms of excisional surgery. Lesions extending proximal to the free portion of the penis yet not extensively invading the tunica albuginea or regional lymph nodes can be treated by sheath ablation and partial phallectomy, creating an urethral stoma at the level of the former preputial orifice or slightly caudal to that.² If solely the glans or the free portion of the penis are affected, partial phallectomy can be performed, sparing most of the penile shaft. Techniques for partial phallectomy include those described by Scott, Vinsot, and Williams and mainly differ regarding the orientation and shape of the surgically created urethral stoma or how hemostasis of the penile cavernous bodies is achieved.1 If the neoplastic lesion has invaded the tunica albuginea, prepuce and regional lymph nodes, preputial ablation and penile amputation and creating a perineal urethrostomy are indicated. A recently described technique using a strangulating latex loop applied with a so-called Callicrate Bander³ can be performed in standing, sedated equids thus offering a well-tolerated4 and cost-effective treatment option for aged subjects with advanced stages of SCC.

In younger and middle-aged equids, equine sarcoids, melanoma (in grey horses), papilloma, cutaneous lymphoma, and fibrosarcoma are other neoplastic conditions that may affect the external male genitalia. However, and unlike with SCC, these usually involve the prepuce and rarely the glans or free part of the penis. Therefore, segmental posthetomy (or reefing) to remove a circumferential segment of the affected prepuce can be curative. Although it is usually recommended to restrict segmental posthetomy to the inner lamina of the preputial fold1 (i.e. portions of the prepuce distal to the preputial ring), this may also include the preputial ring and outer lamina of the preputial fold. Such a more extensive posthetomy, often referred to as “Adam’s procedure”, can also be used to salvage horses with chronic paraphimosis accompanied by penile paralysis and fibrosis. More extensive surgeries involving the resection of the normally well-vascularized preputial and penile tissues are inherently associated with the risk of postoperative swelling and hematoma formation. Importantly, intact stallions should be castrated two to three weeks prior to partial phallectomy or posthetomy surgery to avoid penile erection post-operatively and decrease the risk of hematoma formation. Whenever a urethral stoma is created in conjunction with a partial phallectomy, post-urination haemorrhage is a frequently encountered complication of penile surgery. In most cases, post-urination hemorrhage is self-limiting and transient in nature. If, however, persistent post-urination hemorrhage develops and needs to be addressed, a perineal incision into the corpus spongiosum reliably helps resolve this complication.⁵