Surgical diseases of the urethra

Why do most urethral diseases occur in males?

Reflection of narrow diameter & long length of urethra

Describe the anatomical portions of the urethra in males

• Prostatic

  • At neck of bladder

  • Surrounded by prostate

• Pelvic (membranous)

  • From prostate to ischial arch

  • Vulnerable to injury by pelvic fractures

• Penile (cavernous)

  • Canine urethra occupies groove in os penis

  • Limited distension, prone to obstruction

Describe the anatomy of the urethra in females

• Urethra enters vestibule 2-5mm caudal to the vaginovestibular junction

• Dorsal urethral wall is in close association with the ventral wall of the vagina

• Urethra is relatively straight and short compared to male urethra

• Urethra is wider and mucosa is folded —> allows distension compared to male urethra

How does cats urethra differ in cats compared to dogs

• Cats have long abdominal portion

• Two bends —> one at caudal border of ischium and the other at the base of the penis (penile flexure)

  • Obstruction is common

How does the urethra in the female cat/bitch differ compared to males?

Male urethra long, narrow, less distensible, has several bends —> more commonly have obstructive diseases

Females have shorter, wider more distensible & straighter urethra

List the congenital urethral abnormalities

• Hypospadias, epispadias (uncommon) —> incomplete formation of urethra, cleft scrotum, incomplete formation of prepuce, hypoplastic penis

• Urothrorectal fistula (rare):

  • Development abnormality of foetal cloaca, communication between urethra and rectum persists

  • Urine is passed from anus and vulva/penis, recurrent UTIs

How are hypospadias, epispadias treated?

Resection of hypoplastic penis if becoming self traumatised or dessicated

How is urethrorectal fistula treated?

Resection of fistula (referral)

List some of the common acquired urethral lesions

• Urethritis

• Urethral prolapse

• Urethral obstruction

• Neoplasia

• Stricture

What is urethritis usually associated with? What are the predisposing factors?

• Associated with —> other inflammatory disorders of the urogenital tract —> cystitis, prostatitis, vaginitis

• Predisposing factors —> trauma from urethral calculi or iatrogenic (catheterisation), or neoplasia predisposes

What can urethritis lead to?

Stricture formation

Urethral prolapse

What are the clinical signs of urethritis and how is it treated?

Clinical signs associated with underlying disease

Treat underlying cause

What is the pathogenesis of urethral prolapse?

Which breeds is it common in?

Urethral infection, sexual excitement?

Brachycephalic breeds

What are the clinical signs of urethral prolapse?

• Excessive licking penis/prepuce

• Protruding urethral mucosa (pink/red mass at tip of penis)

• Profuse intermittent bleeding from traumatised prolapsed urethral mucosa

How is urethral prolapse treated?

• Reduce prolapse and place purse string suture around tip of penis, remove suture after 5-7 days

• Resection of prolapsed tissue and suture penile mucosa to urethra, simple cont. pattern

• Castration recommended

Why is urethral obstruction so urgent?

• Can be fatal

• Obstruction may be partial or complete:

  • Failure to eliminate urea and potassium

  • Hyperkalaemia can cause cardiac arrhythmias

  • Can cause permanent renal damage

  • Very painful

  • Overstretches bladder: risk of atony or rupture

What are the causes of urethral obstruction?

• Urethral calculi (more common in males —> longer, narrower urethra)

• Urethral plugs (cats)

• Prostatic disease (dogs)

• Displacement of the bladder through hernia or body wall rupture

• Urethral neoplasia (bitches)

• Bladder neck neoplasia

• Secondary to urethral stricture (more common in male cats and dogs)

• Fracture of the os penis associated with trauma, bite wounds, etc (male dogs)

• Blood clots (haematuria is more common than passing blood clots)

• Granulomatous urethritis (bitches —> rare)

What are the clinical signs of urethral obstruction?

Variable —> depends on degree & duration of obstruction

• Repeatedly straining to urinate

• Dysuria

• Anuria

• Haematuria

• Excessive licking of prepuce/penis (especially male cats)

• Dripping urine

• Inappetence, lethargy, vomiting

• Abdominal distension/pain

• Collapse

How is urethral obstruction diagnosed?

• History

• Clinical findings —> large firm bladder upon abdominal palpation, inability to pass urinary catheter in male dog

• Serum biochem —> assess urea, creatinine, potassium

• Radiography —> pull hindlimbs back because fabellae can look like urethral calculi

• Ultrasound examination

How is urethral obstruction managed?

Immediate priorities

• Empty bladder —> by cystocentesis or catheterisation

• Start IVFT

• Check electrolyte status and treat hyperkalaemia if present

• Provide pain relief

• Then investigate cause of urethral obstruction

How would you manage urethral obstruction due to urethral calculi?

• Empy bladder by cystocentesis

• Fluid therapy

• Attempt catheterisation (usually requires GA) —> pass catheter to obstruction and flush repeatedly with saline

• Check bladder size whilst flushing and empty bladder by cystocentesis (some saline will pass obstruction & will fill bladder)

• Once obstruction is relieved pass catheter to bladder and empty

• Perform retrograde urethrogram to confirm urethral patency

• Retrieve calculi from bladder by cystotomy

When is a urethrotomy in male dogs indicated?

Firmly lodged urethral calculi at base of os penis that can't be flushed to bladder

How would a urethrotomy be performed?

• Pass catheter to site

• Make ventral longitudinal midline skin incision just caudal to os penis

• Reflect retractor penis muscle

• Make longitudinal incision through urethra over calculus

• Remove calculus (submit for analysis)

• Advance catheter

• Suture incision with simple interrupted / cont. pattern

• Remove catheter

What are the potential complications of a urethrotomy?

• Haemorrhage from urethra —> can be profuse, exacerbated by urination and self trauma so must wear collar

• Urine passing into subcut tissues complicates wound healing causing local cellulitis and skin slough

• Stricture formation (post-op) with recurrent urethral obstruction

*Retrograde flushing is preferred tx option

What is a urethrostomy? When is it indicated?

Creation of a permanent urethral opening

Indications:

• Failure to retrograde flush urethral calculi to bladder

• Recurrent urolithiasis with repeat urethral obstruction despite medical management

• Urethral stricture

• Severe penile trauma

What are the potential sites for urethrostomy?

Scrotal (only male dogs)

• Preferred site if dog is/can be castrated

  • Urethra wide and superficial

  • Less cavernous tissue surrounding urethra so less intra and post op haemorrhage

Pre-scrotal (only male dogs) —> urethrotomy more commonly performed at this site

Perineal (only in cats)

Prepubic (rarely performed, salvage of intrapelvic urethral rupture in cats and dogs)

How is scrotal urethrostomy performed in dogs?

• If dog not castrated, perform castration and scrotal ablation

• If already castrated —> midline incision in position of scrotum

• Reflect retractor penis to side, make incision

• Suture urethra to skin —> simple interuptted / cont. pattern

• Close skin and subcut tissues cranial and caudal to stoma as necessary

• Post-op care

How must urethral catheterisation be performed in cats?

Grab very base of prepuce to keep penis exteriorised

Pull caudally and lift dorsally to draw urethral bends into straight line

What is perineal urethrostomy indicated for?

• Failure to relieve urethral obstruction by retrograde flushing

• Recurrent/chronic urethral obstruction

• Penile urethral stricture

• Severe penile urethral trauma

What are the possible complications of feline perineal urethrostomy?

• Wound breakdown/cellulitis

• Stricture formation

• Recurrent UTI

• Perineal hernia

What are the causes of urethral trauma?

• Abdominal trauma

• Pelvic fracture (laceration of intrapelvic urethra by fracture fragments)

• Iatrogenic during catheterisation

What are the clinical signs of urethral trauma?

• Haematuria, dysuria, anuria

• Pain

• Abdominal distension

• Inappetence, lethargy, vomiting

• Collapse

• Discolouration of skin/cellulitis of perineum, thighs, caudal abdomen

How is urethral injury diagnosed?

• History

• Radiography —> plain or retrograde urethrogram

• Serum biochemistry —> elevated urea, creatinine, potassium

How is urethral injury treated?

• Establish urethral patency if possible by gentle catheterisation

• Stabilise patient before treatment

• Conservative treatment —> leave indwelling urethral catheter for 3-10 days if minor trauma

• Refer for surgery if extensive trauma

How is prepubic urethrostomy performed?

• Salvage procedure for intrapelvic urethral injury

• A new urethral opening is created on ventro-caudal abdomen

• Performed when insufficient urethral length to perform urethrostomy at other sites