Urethral disease

Question 1

What are the causes of urethral obstruction in cats

Answer 1

Obstructive idiopathic cystitis (30%)

Urethral plugs (mucous and/or crystalline) (60%)

Uroliths (10%)

Urethral stricture (usually a prior history of catheterization)

Urethral trauma

Urethral neoplasia (rare)

Question 2

What are the risk factors for urethral obstruction

Answer 2

The risk factors for urethral obstruction are similar to those for FIC:
- Male
- Young age
- Obesity
- Indoor lifestyle
- Inactivity
- Dry food diet

Question 3

What is the most common cause of urethral obstruction and what is it composed of

Answer 3

Urethral plugs are the signle most common cause of urethral obstruction in cats

Most plugs have a high matrix content (>50%) within which crystalline material, cells and cellular debris becomes trapped
- together, these components form the urethral obstruction
- it is likely that idiopathic cystitis is the cause of proteinaceous material leakage into the urine
- in the vast majority of cases, the crystalline component of urethral plugs is struvite

Question 4

What is the treatment implication resulting from the crystalloid component of the urethral plugs

Answer 4

In cats that have experienced urethral plugs, the diet should be modified to under-saturate the urine with magnesium, ammonium, and phosphate, and thus at least eliminate the crystalloid component that may contribute to repeat plug formation

Thus, dietary modification to eliminate struvite crystalluria may help prevent recurrence

Question 5

What is the cause of urethral spasm

Answer 5

Pain and inflammation of the bladder and urethra result in muscle spasm and functional obstruction

Question 6

When a urethral spasm should be suspected

Answer 6

Urethral spasm should be suspected/anticipated in any cat where:
- an indwelling catheter is used
- dysuria is present with no physical urethral obstruction (confirmed radiographically)

Question 7

What are the causes for urethral stricture

Answer 7

Urethral strictures are an important cause of signs of lower urinary tract disease

Strictures may be:
- naturally occuring (e.g., occuring after urethral trauma during the passage of a small urolith)
- iatrogenic (i.e., caused by catheterization)

Question 8

How is a diagnosis of urethral stricture made

Answer 8

Diagnosis is made with retrograde urethrography showing the site of urethral stricture

Question 9

How can you minimize the risk of iatrogenic stricture

Answer 9

Adequate anesthesia, sedation and analgesia should be used

Wherever possible a soft flexible catheter should be used

There should be adequate lubrication

The penis should be extruded and pulled distally to “strtech” the urethra into a straight line to facilitate catheterization

Question 10

What is the treatment for urethral stricture

Answer 10

Urethrostomy