Urethral Prolapse and Neoplasia in Dogs

Overview of Canine Urethral Prolapse and Neoplasia

Urethral prolapse describes the protrusion of the lining of the distal or tail end portion of the urethra through the external urethral opening. Urethral neoplasia is cancer of the urethra. Urethral prolapse and neoplasia are most common in dogs, especially English bulldogs and Boston terriers, and most often affects young to middle aged male dogs.

The prolapsed urethra is a red or purple, swollen, doughnut-shaped mass protruding from the distal end of the penis. Urethral cancer most often affects middle aged to older female dogs

Causes of Urethral Prolapse in Dogs

• Prolonged sexual excitement
• Urethral infection
• Stones in the urinary tract (urolithiasis)
• Increased intra-abdominal pressure as a consequence of brachycephalic syndrome, which is a disorder of short-nosed dogs that compromised upper airway function due to anatomical abnormalities

Causes of Neoplasia in Dogs

• Idiopathic (no known cause)
• Squamous cell carcinoma and transitional cell carcinoma are most common

What to Watch For

Signs of urethral prolapse and neoplasia in dogs may include:

• Straining to urinate (stranguria)
• Bloody urination (hematuria)
• Frequent urination (pollakiuria)
• Bleeding from the urethra independent of urination
• Urinary blockage
• Excessive licking of the penis

Diagnosis of Urethral Prolapse and Neoplasia in Dogs

• Visual inspection is often helpful in diagnosing a urethral prolapse.
• Ejaculation may help evaluate the urethra during a penile erection, as occasionally a urethral prolapse is only present at that time.
• Rectal palpation may reveal a palpable mass or thickening consistent with cancer.
• Complete blood count (CBC)
• Biochemical profile
• A urinalysis and urine culture and sensitivity
• Abdominal radiographs (X-rays)
• Abdominal ultrasound

Additional diagnostic tests specifically for urethral neoplasia include:

• A contrast cystourethrogram (dye study of the bladder and urethra) may be helpful in diagnosing urethral neoplasia
• Urethroscopy evaluates the inside of the urethra with a tiny instrument.
• Computed tomography (CT scan)
• Urethral cytology and/or biopsy

Treatment for Urethral Prolapse in dogs

• Treatment may not be required if the prolapsed urethra is asymptomatic or only associated with episodic bleeding.
• If the prolapsed urethra is present only during penile erection, consider castration prior to attempting surgical removal of the prolapsed tissue.
• Consider surgery for patients with excessive bleeding, pain or extensive ulceration and/or necrosis of the prolapsed tissue.
• Amputation of the prolapsed urethral may be necessary, especially in cases where there is severe devitalization of tissue.
• An Elizabethan collar may be needed to reduce licking-induced trauma postoperatively.
• Antibiotics for associated infection.
• Estrogen compounds to decrease the frequency of erections.
• Remove any trauma that may be causative, such as stones or catheters
• Address underlying cancer as indicated

Treatment for Urethral Neoplasia in Dogs

• Relieve urinary obstruction if present.
• Intravenous fluid therapy and electrolytes as needed.
• Surgical excision in some cases
• Chemotherapy
• Piroxicam (Feldene®) and nonsteroidal anti-inflammatory drugs may be of benefit in some cases.
• Radiation therapy

Home Care and Prevention

Monitor your dog’s ability to urinate and administer all medication as directed by your veterinarian. Return for follow-up as directed.

Limit your male dog’s exposure to female dogs or situations that predispose to penile erections. Addressing underlying causes at once may help prevent urethral prolapse.