SURGERY
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sleeve to assist with its passing through the two obturator
foramina to form a sling across the dorsal aspect of the
distal urethra when the animal is standing. The plastic
sleeve is removed before closure of the episiotomy.
The article by Claeys et al. (2010) describes the results in
female dogs with a short-term cure in 6 of the 7 cases 13 .
This polypropylene tape that can now be used as an
artificial urethral sling, and can be obtained from Price
Medica ([email protected]). Animals treated with
the TVT-O by Dr Hans van der Zee in our Small Animal
Surgery Section performed well over the first 12 months.
5. Artificial sphincters
Hydraulic urethral occluders are being used with increasing
frequency as artificial sphincters for the treatment of
USMI in female dogs 14-16 . The artificial canine urethral
sphincter (DOCXS Biomedical Products & Accessories,
Ukiah, California) consists of a medical grade silicon cuff
and tubing and a subcutaneous access port. Cuff sizes
are available in lumen diameters ranging from 6 mm
to 16 mm and width from 11 mm and 14 mm. The size
selection is dependent on the measurement of the urethral
circumference at the location of placement (which should
be at least 2 cm caudal to the neck of the bladder. Before
placement, the cuff should be tested to verify that it is
functional. The cuff, tubing and port should be flushed
with sterile saline to remove any air bubbles. The urethra
is dissected circumferentially at the placement site and its
circumference is measured with a Penrose drain.
The un-inflated sphincter cuff is placed around the urethra
and secured to itself with non-absorbable monofilament
nylon sutures. The associated tubing is tunnelled through
the body wall and exited into the subcutaneous space of
the caudal abdomen or inguinal region, and secured to
the port with a boot fastener 16 . The port is then secured
to the external abdominal wall fascia with monofilament
nylon sutures. The bladder should be manually expressed
before abdominal closure to verify that the urethra is not
obstructed with the occluder in place 16 .
Cuff inflation is delayed for up to 6 weeks to allow resolution
of inflammation and to permit revascularization of the
dissected portion of the urethra. If the patient remains
incontinent after artificial sphincter placement, then
the cuff is typically inflated about 25% by percutaneous
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injection into the port with sterile saline through a 22G
Huber needle. In an initial report, three out of four dogs
required inflation of the cuff one or more times after
sphincter placement 15 . The fourth dog required port
removal because of superficial ulceration, but all four
dogs were incontinent without medical management 26
to 30 months after artificial sphincter placement 15 .
REFERENCES
1.
Holt P H. Sphincter Mechanism Incontinence. 2012. In: Veterinary Sur-
gery, Small Animal. Tobias K M & Johnston S A (eds.), Elsevier Saunders,
St Louis, Missouri. Chapter 118:2011-2018
2. Holt PE. 1985 Urinary incontinence in the bitch due to sphincter mecha-
nism incompetence: surgical treatment. Journal of Small Animal Practice
Vol.26: 237 - 246
3. Holt PE. 1990 Long term evaluation of colposuspension in the
treatment of urinary incontinence due to incompetence of the urethral
sphincter mechanism in the bitch. The Veterinary Record Vol. 127:537
- 542
4. Aaron A, Eggleton K, Power C, et al. 1996 Urethral sphincter mecha-
nism incompetence in male dogs: a retrospective analysis of 54 cases.
The Veterinary Record Vol. 139:542 – 546
5. Thrusfield MV, Muirhead RH, Holt PE. 1998 Acquired urinary inconti-
nence in bitches: its incidence and relationship to neutering practices.
Journal of Small Animal P