Paraphimosis and Priapism

Chapter 141 Paraphimosis and Priapism



Mark C. Rochat, DVM, MS, DACVS



KEY POINTS



• Paraphimosis is the inability to reduce the penis into the prepuce.

• Paraphimosis can result from a number of causes and should be considered an emergency condition.

• Recurrent paraphimosis can be managed with phallopexy.

• Priapism is persistent penile erection in the absence of sexual stimulation.

• Priapism can result from many causes and should be considered an emergency condition.

• Priapism can be classified as high flow or low flow; low-flow priapism is far more common.

• Oxygen free radical scavengers may play an effective role in the management of priapism.

• Corporal aspiration and saline lavage, coupled with injection of phenylephrine, should be the first-line element of management for low-flow priapism.

• Surgical shunts or other interventions should be reserved for cases unresponsive to medical management.


PARAPHIMOSIS


Paraphimosis results when the penis cannot be ensheathed in the prepuce.1,2 Paraphimosis is more common in dogs than cats and may be more common in young dogs. Paraphimosis can result from a number of conditions (Box 141-1). Initially, the exposed penis often appears normal but may be engorged if the paraphimosis occurs following an erection, or may be edematous due to continued environmental exposure. Continued environmental exposure and constriction results in venous congestion, mucosal drying, and further increase in penile edema.1,3 With time, thrombosis of the penile vasculature, mucosal fissuring, and necrosis may result.



Box 141-1 Causes of Paraphimosis



• Coitus

• Penile entrapment by hair around the preputial orifice

• Mild phimosis

• Trauma (including fractures of the os penis)

• Neoplasia

• Pseudohermaphroditism

• Foreign bodies that encircle and constrict the penis

• Penile hematomas

• Preputial orifice inversion

• Preputial hypoplasia

• Preputial muscular weakness

• Chronic balanoposthitis

The diagnosis of paraphimosis is made by visual examination of the genitalia. Because paraphimosis is very painful in the early stages, sedation or anesthesia may be required to examine the penis and prepuce. The extent of mucosal injury and the potential for penile necrosis and urethral compromise should also be assessed.


Treatment of paraphimosis involves gentle cleaning of the penis and judicious debridement of necrotic tissue. Encircling bands of hair or other material should be removed carefully.1 When possible, the penis is then reduced manually into the prepuce. Cooling the penis to cause vasoconstriction or applying topical agents such as lubricants or dextrose solutions may help reduce the edema and facilitate reduction.1 Surgical enlargement of the preputial orifice may be required to achieve reduction if it cannot be accomplished manually.2 A temporary purse-string suture placed in the skin of the preputial orifice can be inserted to maintain reduction of the penis after it has been replaced in the prepuce.


Following the initial intervention, the penis can be extruded gently on a daily basis for several days and antibiotic-steroid ointment applied to prevent adhesions between the prepuce and the penis.1 If the urethral lumen has been compromised but the penis is otherwise viable, a Silastic urethral catheter that is smaller than the diameter of the urethral lumen should be inserted to decrease the risk of urethral occlusion secondary scar tissue.1


Several surgical procedures can be used to manage paraphimosis. If the penis cannot be maintained in the prepuce or the paraphimosis recurs repeatedly, phallopexy can be performed by creating a permanent adhesion between the shaft of the penis and the dorsal or dorsolateral preputial mucosa.4 If inadequate preputial length is the cause of the paraphimosis, the prepuce can be advanced surgically. Preputial advancement usually is successful only if the length of exposed penis is limited to 1 to 2 cm.2 If more than 1 to 2 cm of the penis is exposed, preputioplasty or partial penile amputation may be required.2 Partial penile amputation is also the management for penile neoplasia, severe penile trauma, congenital abnormalities, and chronic paraphimosis that is unresponsive to less aggressive treatments. If the penis is necrotic, complete penile amputation with scrotal urethrostomy may be necessary.


Paraphimosis can recur, especially if it is associated with sexual behavior. Efforts to prevent recurrence, such as trimming of the preputial hair, careful inspection of the penis and prepuce after breeding, administration of progestogens, and castration, can be employed.3



PRIAPISM


Priapism is a persistent penile erection in the absence of sexual stimulation. The penis cannot be reduced manually into the prepuce. Priapism is a rare disorder in domestic animals. It has been reported in the dog, horse, cat, rat, and sea lion. Priapism can be confused with the late stages of paraphimosis or penile paralysis. Unlike priapism, penile paralysis results in a flaccid penis that cannot be retracted into the prepuce. Penile paralysis most commonly occurs in the horse after giving α-adrenergic blocking agents such as phenothiazine-derivative tranquilizers. Penile paralysis has not been reported in the dog.



Etiology and Pathophysiology


Unlike paraphimosis, which is largely initiated by physical events or structural abnormalities, priapism is initiated by alterations in the mechanisms that control penile erection. The physiology of erection is a complex and detailed subject. In the interest of brevity, the reader is directed to a review of the physiology of normal penile erection.5


The causes of priapism in dogs and cats are diverse (Box 141-2), and many of the exact mechanisms are unknown; however, phenothiazine-derived tranquilizers are reported to create priapism in the horse by blocking sympathetic impulses that initiate detumescence while also causing paralysis of the retractor penis muscle. Priapism in association with phenothiazine-derivative tranquilizers develops more often in stallions and may be a consequence of their high androgen concentrations.



Box 141-2 Causes of Priapism



• Acepromazine

• Amphetamines

Related posts:

  1. Deteriorating Mental Status
  2. Hyperthermia and Fever
  3. Ventilator-Associated Lung Injury
  4. Allergic Airway Disease in Dogs and Cats and Feline Bronchopulmonary Disease

Stay updated, free articles. Join our Telegram channel
Tags:
Sep 10, 2016 | Posted by in SMALL ANIMAL | Comments Off on Paraphimosis and Priapism

Full access? Get Clinical Tree
Get Clinical Tree app for offline access