Disorders of the Penis and Prepuce

By | March 9, 2015

1) My intact male dog always has a glob of green goohanging by his prepuce. Is that abnormal?

All intact male dogs make prostatic fluid all the time, whether they are being used for breeding or not. Most of the prostatic fluid runs into the bladder, but some runs through the penis and accumulates at the tip of the prepuce; this is normal. If the dog licks excessively, the surface of the penis is red or rough, or there is such a large amount of discharge that it drips, that is abnormal and the dog should be seen by a vet.

Persistent penile frenulum

Development

The penis and prepuce are joined during embryonic development by a tissue called the balanopreputial fold. This fold should dissolve, under the influence of testosterone, before birth. In some dogs, persistence of a portion of this fold leads to a permanent connection between the ventral portion of the penis and the prepuce, such that the penis cannot be completely extruded. The penile frenulum also may be associated with the penis only, usually causing ventral deviation of the tip of the penis as the frenulum attaches the tip to the shaft ().

Signalment

There is no breed predisposition described for this uncommon condition. It is a congenital condition and may be hereditary.

History and clinical signs

Because the penis cannot be completely extruded from the penis, the animal may have dermatitis in the groin from urine scald, inflammation of the penis and prepuce (balanoposthitis; see later discussion), refusal or inability to mate, or obvious deviation of the penis as it becomes erect.

Diagnosis

Persistent penile frenulum is easily diagnosed on physical examination.

Treatment

The band of tissue connecting the penis to the prepuce is fibrous and rarely has a significant blood supply. Surgical transection of the band is curative. If the band is large, sedation or anesthesia of the dog and suturing of the transection site may be indicated.

Prognosis

Prognosis for normal function and a decrease in clinical signs is very good.

Phimosis, paraphimosis, and priapism

Balanoposthitis

Development

Balanitis is inflammation of the surface of the penis. Posthitis is inflammation of the prepuce. These conditions usually occur together; this condition is called balanoposthitis, which develops because of invasion of the mucosal surfaces with the normal bacterial inhabitants. Conditions that allow bacterial colonization include trauma, allergies, foreign bodies, urinary incontinence, and cancer. Often no underlying cause for infection can be identified. Although infection with bacteria is most common, some viral infections, most notably canine herpesvirus, also can cause balanoposthitis.

Signalment

Dogs of all ages and breeds may be affected. Intact male dogs with excessive preputial discharge always should be evaluated for prostate disease when presented with apparent balanoposthitis ().

History and clinical signs

Dogs have excessive preputial discharge that varies from bloody to pus-like but generally show no other clinical signs except licking at the prepuce excessively. Intact male dogs normally secrete prostatic fluid at all times, not just when being used for breeding, and it is normal to see a small amount of yellow-green discharge at the urethral orifice. This discharge should not be foul smelling and should not be copious.

Diagnosis

The penile and preputial mucosae are inflamed, and discharge is present over the surfaces and on the dog’s flanks (). Signs of underlying disease may be present, for example, red skin and secondary skin infection in the groin of dogs with underlying allergies.

Treatment

If an underlying cause can be identified, it should be treated. The preputial discharge should be cultured and appropriate antibiotic therapy instituted. Flushing of the prepuce with mild antiseptic solutions may be beneficial; check with a veterinarian for an antiseptic that will not harm the mucosal tissue.

Prognosis

If an underlying cause can be identified and treated, and infection controlled, prognosis is excellent. If no underlying cause can be identified, intermittent antibiotic therapy may be necessary, perhaps for the animal’s life.

Hypospadias

Development

During normal embryologic development, the penis forms around the urethra, with both tissues rolling together and closing up on the ventral surface under the influence of a metabolite of testosterone, dihydrotestosterone. If there is a defect in urethral closure, the urethra remains opens, and urine is expressed from an area other than the tip of the penis. This abnormal urethral opening is called hypospadias. This can be an accident of development, or it may occur in pups born to bitches given excessive estrogen or progesterone during pregnancy. Hypospadias may be seen in conjunction with other defects of development of the genitourinary tract in male dogs.

Signalment

There is no recognized breed predisposition for this congenital defect.

History and clinical signs

Different degrees of hypospadias exist. The urethral opening may be present near the tip of the penis (glandular type), on the shaft of the penis (penile type), at the level of the scrotum (scrotal type), or beneath the anus (perineal type). Clinical signs are less severe with the penile and glandular types than with the perineal and scrotal types. Some dogs with hypospadias show no evidence of an abnormality. Clinical signs may include urinary incontinence, urinary tract infections, dermatitis due to urine scald, and inability to mate.

Diagnosis

Hypospadias is easily diagnosed on physical examination.

Treatment

Glandular and perhaps penile hypospadias potentially can be treated by surgical closure of the defect. Constriction of the urethra and subsequent urinary tract disease are possible complications. The more severe forms of hypospadias, the scrotal and perineal types, may require penile amputation and perineal urethrostomy, which is creation of a new urethral opening not incorporating the penis.

Prognosis

Prognosis is dependent on site of the defect. Prognosis is better with glandular and penile hypospadias than with scrotal and perineal hypospadias. I am aware of one male dog with glandular hypospadias that was successfully used for breeding, even before surgical repair.

Fracture of the os penis

Urethral prolapse

Development

The urethra pushes out through the tip of the penis, forming a ball of red mucosa. The amount of tissue may appear to increase with erection of the penis.

Signalment

This most commonly occurs in dogs less than 2 years of age. The two breeds reported to be predisposed are the Boston terrier and English bulldog.

History and clinical signs

Dogs with urethral prolapse present with bleeding from the penis that may increase in volume with sexual excitement.

Diagnosis

Urethral prolapse is easily is diagnosed on physical examination ().

Treatment

Conservative treatment, consisting of cage rest away from estrous bitches and tranquilization, is rarely effective. Surgical repair is preferred. The prolapsed tissue is removed, and the remaining tissue is sutured to create a new, smooth urethra to the tip.

Prognosis

Recurrence is common. Castration may be of benefit in some animals. There are reports of animals successfully mating after surgical repair for urethral prolapse.

Penile and preputial neoplasia

Development

Neoplasia of the penis and prepuce is uncommon in dogs. The most common types described are squamous cell carcinoma, an invasive cancer of skin cells, and transmissible venereal tumor (TVT). TVT is an infectious tumor, spread by mating or by licking at the genitalia of an affected animal. TVTs do not have the same chromosome number as do regular dog cells, and their origin is unknown.

Signalment

Most penile tumors occur in older animals. TVTs occur in young, sexually active, free-roaming dogs. There is no breed predisposition for either type of tumor. TVTs are much more common in tropical areas of the world that have large free-roaming dog populations than in temperate regions of the world. I am based in the northern United States and have seen only one case of TVT, in a dog that had lived for years in Central America before being castrated and brought to the United States.

History and clinical signs

The presence of penile tumors may be associated with pain at the time of mating, bleeding from the penis or prepuce, a thickened appearance of the prepuce, or protrusion of a lesion from the urethral opening. Squamous cell carcinomas and TVTs often have a “cauliflower-like” appearance. TVTs are often covered with blood and are very soft.

Diagnosis

Penile neoplasia is easily diagnosed by physical examination. Definitive diagnosis of TVT requires histopathology, which can be performed easily by your veterinarian because this tumor is very fragile and cells easily fall away when the tumor is swabbed or compressed with a glass slide. In the dog from Central America described previously, simple manipulation of the prepuce caused a piece of tumor to fall off, giving us an excellent sample to submit for diagnosis.

Treatment

Squamous cell carcinoma may be an invasive tumor, spreading deep within the penile tissue. It also may spread to other tissues in the body. Penile amputation may be required. TVT is easily treated with chemotherapy; surgery rarely is required.

Prognosis

Prognosis for life with squamous cell carcinoma is dependent on whether or not the tumor has spread to other tissues by the time of diagnosis. If it has not, surgery can be curative. Prognosis for TVT is very good with appropriate chemotherapy.

Test your understanding

Your 2-year-old intact male dog licks at his penis incessantly, occasionally exposing the penis for extended periods of time. The penis looks red at the tip and often is covered with green discharge. What is the most likely rule-out?

The most likely rule-out is balanoposthitis, inflammation of the mucosal surfaces of the penis and prepuce. This is infection with the normal flora overlying some initial cause of inflammation, such as neoplasia (unlikely in such a young dog) or allergies.

Selections from the book: “The Dog Breeder’s Guide to Successful Breeding and Health Management”, 2006.

Incoming search terms:

  • dog prepuce infection