Surgical conditions of the male equine reproductive tract (Proceedings)
Traumatic Injuries to the Penis and Prepuce
Lacerations to the Penis and Prepuce
Lacerations to the stallion's penis typically occur when a stallion attempts to breed a mare across a fence, from the mare's tail hair or breeding stitch during coitus, or from improperly fitted stallion rings. Penile lacerations in geldings are the usually the result of trauma or from iatrogenic damage during castrations attempts. Most penile lacerations involve the skin and subcutaneous tissues, however, lacerations into the cavernosal tissues and urethra have been reported. Any horse with a penile laceration should be examined to determine the extent of the laceration. An acute wound should be cleaned, debrided and sutured primarily, if possible. The suture chosen should be of a soft nature, such as Vicryl, to avoid irritating the prepuce when the penis is retracted into the sheath. Any rent or tear in the tunica albuginea should be closed to prevent a shunt from forming between the cavernosal tissues and the penile vasculature. If the urethra is involved, the nature of the laceration determines whether or not surgical repair is necessary. Smaller longitudinal lacerations may close with second intention healing. However, larger longitudinal and transverse lacerations of the urethra will leak urine, creating cellulitis of the soft tissues and possibly form a fistula with the skin or cavernosal tissues. In these cases, primary closure of the urethral defect with diversion of urine via a urinary catheter or proximal urethrostomy will decrease the chances of urethral stricture. If the wound is chronic in nature or grossly infected, it should be cleaned daily and topical antimicrobial ointment applied. In cases of severe, intractable penile injury, amputation may be best option.Preputial Injuries
Like penile injuries, preputial lacerations are often the result of trauma. All but the most superficial of preputial lacerations should be closed primarily. Due to the ventral nature of the prepuce, open lacerations generally develop cellulitis and swelling. Closure of these lacerations prevents the horse from protruding the penis through the defect in the prepuce. In addition, second intention healing of the prepuce often results in a scarring which limits the ability of the horse to retract its penis into the sheath.
Penile hematomas result from the rupture of the cavernosal tissues or from disruption of the subcutaneous vascular plexus. They frequently occur following a kick from a mare when breeding, a sudden movement of the mare during coitus or from mounting stationary objects. Bleeding occurs rapidly, with the penis and prepuce swelling markedly. Eventually, venous and lymphatic return as well as urination may be affected. Often, the horse is unable to retract the penis into the sheath and paraphimosis results.
In the acute phase, application of a pneumatic tourniquet may limit the degree of hemorrhage. The tourniquet is applied at distal end of the penis and worked proximally. The tourniquet may need to be re-applied as the swelling is reduced. The penis should be returned to the sheath and kept in place by means of a sling support or purse string suture in the prepuce. Hydrotherapy with a cold hose may also be beneficial. Emollient antimicrobial salve should be applied to the penis to prevent the skin from cracking and sloughing. In more chronic cases, the penis may be deviated due to the presence of the hematoma. The use of ultrasound to identify a hematoma in the subcutaneous tissues can aid in surgical evacuation of the hematoma. As with most chronic penile hematomas, the skin is usually too damaged to attempt a primary closure. Urethral patency should be checked in all cases to avoid bladder rupture.