Urinary incontinence

Question 1

How frequent is urinary incontinence in cats

Answer 1

Urinary incontinence is a rare clinical presentation in cats

Question 2

Describe the normal physiology of urinary continence

Answer 2

The detrusor muscle of the bladder contains both
- sympathetic receptors (b-adrenergic receptor stimulation causing relaxation)
- parasympathetic receptors (stimulation causing contraction)

The internal urethral sphincter is composed of smooth muscle that contains sympathetic (a-adrenergic) receptors
- stimulation causes contraction

The external urethral sphincter is composed of striated muscle

The parasympathetic and somatic nerves arise from sacral spinal cord segments (S1-S3) and travel via the pelvic and pudendal nerves respectively

The sympathetic nerves leave from L2-L5 and travel via the hypogastric nerve

Higher brain centers modify the local reflexes

Question 3

What are the two clinical types of urinary incontinence

Answer 3

Incontinence with a full bladder
- disorders of bladder emptying

Icontinence with a small bladder
- disorders of urine storage

Question 4

What are the main causes for incontinence with a full bladder

Answer 4

Partial urethral obstruction

Neurologic lesions
- congenital spinal defects (e.g., Manx cats)
- trauma (e.g., tail pull injuries)
- neoplasia
- feline dysautonomia

Failure of detrusor to contract
- prolonged distension of the bladder from any cause resulting in a breakdown of the detrusor tight junctions and poor contractility

Question 5

What are the main causes for incontinence with an empty bladder

Answer 5

Ectopic ureters
- congenital
- rare

Urethral hypoplasia
- associated with secondary urethral sphincter mechanism incompetence
- important cause of congenital incontinence in cats
- the urethra is very short and the bladder is largely intra-pelvic
- vaginal aplasia is also commonly seen in affected cats with uterine horns terminating in the dorsal wall of the bladder
- secondary UYIs are common in these cats

Urethral sphincter mechanism incompetence
- reported in neutered female cats
- rare condition
- medical therapy (e.g., alpha agonsists, suprelorin) appears to be quite successful

Detrusor hyperreactivity
- most often seen in association with variouus causes of cystitis
- in cases of long-standing cystitis, there may be fibrosis resulting in a poorly distensible bladder that exacerbates the syndrome