Urethral Sphincter Mechanism Incompetence - Revision history

Bara at 12:47, 9 August 2012

2012-08-09T12:47:45Z

Bara at 14:20, 26 October 2011

2011-10-26T14:20:52Z

HelenD: Created page with "==Introduction== This is the a common cause of '''urinary incontinence in dogs''', especially '''neutered bitches''', although castrated male dogs and entire animals can also be ..."

2011-09-08T09:46:41Z

Created page with "==Introduction== This is the a common cause of '''urinary incontinence in dogs''', especially '''neutered bitches''', although castrated male dogs and entire animals can also be ..."

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==Introduction==
This is the a common cause of '''urinary incontinence in dogs''', especially '''neutered bitches''', although castrated male dogs and entire animals can also be affected.

SMI is most commonly seen as an acquired condition, but may also be seen as a congenital problem in young animals.

'''<u>Congenital SMI</u>''' may occur in conjunction with anatomical defects such as [[Ureteral Ectopia|ureteral ectopia]] and [[Intersex|intersexuality]]. It occurs most commonly in '''large-breed bitches'''. The urethra may be abnormally short of absent, but often no abnormalities are detected apart from a caudally-positioned bladder.

50% of congenital SMI bitches become continent '''following their first oestrus'''.

'''<u>Acquired SMI</u>''' usually follows '''spaying or castrating'''. It is a '''multifactorial disease''' involving: urethral tone, urethral length, bladder neck position, body size and breed, spaying, obesity and hormones. The urethra is usually shorter in affected bitches, and the bladder neck is usually '''intra pelvic'''.

Large and giant breeds are again at risk, in particular the '''Old English Sheepdog, Rottweiler, Doberman''', Weimaraner and Irish Setter.

The link between spaying and acquired SMI is probably due to the '''lack of circulating oestrogens'''. Spaying before the first season may increase the risk of developing the disease, and spayed animals are 8 times more likely to develop SMI than entire animals.

'''Obesity''' may be involved, and some incontinent dogs will improve following weight loss.

==Clinical Signs==
The presenting signs is usually '''passive urinary incontinence''' when the animal is recumbent.

Typically, the animal '''urinates normally''' between episodes of leakage.

The incontinence '''varies in severity''' and can improve or get progressively worse over time.

==Diagnosis==
Diagnosis is based on the history, clinical signs, and in some cases a response to treatment.

Physical examination is usually unremarkable.

Full investigation include:
:'''plain radiography''': intra-pelvic bladder and short urethra
:'''contrast radiography''': intravenous urogram and retrograde vaginourethrogram
:'''ultrasound''': to confirm emptying of ureters into the bladder
:'''urinalysis and bacteriology'''
:'''urodynamic testing''': urethral pressure profilometry

Diagnosis is usually based on the '''exclusion of all other likely causes''' (urinary tract infection, ectopic ureters, neoplasia) and the presence of a '''caudal bladder neck''' on radiography.

A '''positive response to treatment''' may be the only diagnosis possible if finance preclude further testing.

==Treatment==
Treatment can be medical or surgical.

'''Medical treatment''' aims to increase urethral tone and functional length. Drugs include:
:sympathomimetic drugs such as '''phenylpropanolamine''' or ephedrine
:'''exogenous oestrogens''': oestriol
:a combination of the above drugs

Phenylpropanolamine is the first choice and has also been used in male dogs.

In juvenile bitches with congenital SMI, 50% will spontaneously get better following their first season, and therefore these dogs '''should not be spayed''' before their first season and should '''not be given exogenous oestrogens'''. Phenylpropanolamine can be used instead.

There are numerous '''surgical treatments''' available, and involve:
:increasing urethral resistance: peri-urethral surgical '''slings''', '''artificial sphincters''', intra-urethral bulking agents
:increasing urethral length: bladder neck reconstruction techniques
:relocating the bladder to an intraabdominal position: '''colposuspension'''

'''Colposuspension''' carries the lowest complication rate, and the technique is as follows: via a caudal midline laparotomy, using the vagina as a sling, the bladder neck is brought cranially and kept in the intra-abdominal position by sutures placed from the pre-pubic tendon to the lateral walls of the vagina.

50% of animals are '''cured''' following colposuspension, and a further 40% are '''much improved'''. The rest are not generally made worse.

The '''choice of treatment''' is based on the owner's wishes, the age of the animal and its response to previous treatments.

{{Learning
|flashcards = [[Small Animal Abdominal and Metabolic Disorders Q&A 02]]
}}

==References==
Holt, P. (1999) '''Diagnosis and management of canine urethral sphincter mechanism incompetence''' ''Waltham Focus'' Vol 9 No 4

Gregory, S. (2010) '''Urinary Incontinence''' ''RVC student notes''

[[Category:To Do - Helen]]
[[Category:To Do - Review]]

@@ Line 1: / Line 1: @@
 Also known as: '''''SMI'''''
@@ Line 71: / Line 72: @@
 {{review}}
 [[Category:Urological Diseases - Dog]]
 [[Category:Lower Urinary Tract - Pathology]]
 [[Category:Expert Review - Small Animal]]

@@ Line 1: / Line 1: @@
 ==Introduction==
-This is the a common cause of '''urinary incontinence in dogs''', especially '''neutered bitches''', although castrated male dogs and entire animals can also be affected.
+This is a common cause of '''urinary incontinence in dogs''', especially '''neutered bitches''', although castrated male dogs and entire animals can also be affected.
 SMI is most commonly seen as an acquired condition, but may also be seen as a congenital problem in young animals.
-'''<u>Congenital SMI</u>''' may occur in conjunction with anatomical defects such as [[Ureteral Ectopia|ureteral ectopia]] and [[Intersex|intersexuality]]. It occurs most commonly in '''large-breed bitches'''. The urethra may be abnormally short of absent, but often no abnormalities are detected apart from a caudally-positioned bladder.
+'''<u>Congenital SMI</u>''' may occur in conjunction with anatomical defects such as [[Ureteral Ectopia|ureteral ectopia]] and [[Intersex|intersexuality]]. It occurs most commonly in '''large-breed bitches'''. The urethra may be abnormally short or absent, but often no abnormalities are detected apart from a caudally positioned bladder.
 % of congenital SMI bitches become continent '''following their first oestrus'''.
@@ Line 17: / Line 19: @@
 ==Clinical Signs==
-The presenting signs is usually '''passive urinary incontinence''' when the animal is recumbent.
+The presenting sign is usually '''passive urinary incontinence''' when the animal is recumbent. Typically, the animal '''urinates normally''' between episodes of leakage. The incontinence '''varies in severity''' and can improve or get progressively worse over time.
 ==Diagnosis==
@@ Line 37: / Line 35: @@
 Diagnosis is usually based on the '''exclusion of all other likely causes''' (urinary tract infection, ectopic ureters, neoplasia) and the presence of a '''caudal bladder neck''' on radiography.
-A '''positive response to treatment''' may be the only diagnosis possible if finance preclude further testing.
+A '''positive response to treatment''' may be the only diagnosis possible if finances preclude further testing.
 ==Treatment==
@@ Line 52: / Line 50: @@
 There are numerous '''surgical treatments''' available, and involve:
-:increasing urethral resistance: peri-urethral surgical '''slings''', '''artificial sphincters''', intra-urethral bulking agents
+*increasing urethral resistance: peri-urethral surgical '''slings''', '''artificial sphincters''', intra-urethral bulking agents
-:increasing urethral length: bladder neck reconstruction techniques
+*increasing urethral length: bladder neck reconstruction techniques
-:relocating the bladder to an intraabdominal position: '''colposuspension'''
+*relocating the bladder to an intraabdominal position: '''colposuspension'''
 '''Colposuspension''' carries the lowest complication rate, and the technique is as follows: via a caudal midline laparotomy, using the vagina as a sling, the bladder neck is brought cranially and kept in the intra-abdominal position by sutures placed from the pre-pubic tendon to the lateral walls of the vagina.
@@ Line 71: / Line 69: @@
 Gregory, S. (2010) '''Urinary Incontinence''' ''RVC student notes''
-[[Category:To Do - Helen]]
-[[Category:To Do - Review]]
+{{review}}