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An Urban Experience
J. Bartges1
1The University of Georgia, Athens, GA, USA 30606
Objectives of the Presentation
Following this presentation, the attendee should be able to
- describe reasons for medically unresponsive urinary incontinence
- describe pharmacologic and non-pharmacologic management of patients with medically non-responsive urinary incontinence
Urinary incontinence refers to the unconscious
release of urine.(1) It may described as anatomic
versus non-anatomic or neurogenic versus non- neurogenic. Anatomic causes of urinary incontinence include primarily congenital malformations such as ectopic ureter or urethral hypoplasia. These are usually present in pediatric patients. The most common cause of urinary incontinence in adult dogs is urethral sphincter mechanism incompetency (USMI). It is uncommon in male dogs and male and female cats, but may occur
in 5 to 20% of spayed female dogs.(2) Usually urination while awake is normal. Urinary incontinence may also occur due to overflow, bladder hyperactivity, and
reflex dyssynergia. Overflow urinary incontinence is associated with a urethral obstruction and occurs when the pressure in the urinary bladder exceeds the urethral pressure. Bladder (detrusor) hyperactivity may occur with urinary tract infection or urolithiasis and may result in urinary incontinence due to the continued sensation
of urgency. Reflex dyssynergia is a condition where urination begins normally; however, part-way through urination the urethra spasms or closes despite continued attempts at urination.
Treatment of urinary incontinence due to urethral sphincter mechanism incompetency is to stimulate
the urethral smooth muscle resulting in increased
tone of the internal urethral sphincter. Administration
of sympathomimetics (e.g. alpha agonists: phenylpropanolamine) results in continence in 85-90%
of patients. Once a day treatment may be as effective
as three times a day administration and is associated with fewer side effects.(3) Estrogen replacement therapy (estriol, diethylstilbesterol, Premarin) may increase alpha adrenergic receptor responsiveness and improve urethral vascularity and other mucosal characteristics. They are safe and reasonably effective (40-65%); however, estriol (Incurin) is reported to have a 93% excellent response
rate.(4) Gonadotropin releasing hormone (GnRH)
analogs have also been used.(5) In ovariectomized
dogs, chronically unsuppressed FSH and LH release (due to lack of negative feedback) may contribute to urinary incontinence. Administration of GnRH analogs paradoxically reduces FSH and LH over time. It was found effective in 12/13 dogs in one study and in another study 9/23 dogs were continent from 70-575 days with another 10/23 having partial response; however, the 23 dogs also responded to PPA.
In patients with USMI that are unresponsive to pharmacological therapy, there are several potential treatments. The first step is to evaluate the patient
for diseases, diet, or other drug therapy that may worsen urinary incontinence or render medical control inadequate. The urine should be cultured as a bacterial urinary tract infection may be present. Often dogs
with USMI and UTI have normal appearing urine and
no other clinical symptoms of UTI other than urinary incontinence and often eradication of the bacterial
UTI results in continence. Thyroid testing should be performed on patients with medically unresponsive
USMI especially high risk breeds for hypothyroidism
such as retrievers and Doberman pinschers. Diseases, diets, and medications that are associated with polyuria/ polydipsia will worsen urinary incontinence. Evaluate the patient for chronic kidney disease, diabetes mellitus, and hyperadrenocorticism. Some diets have higher content of sodium chloride that induces a diuresis and will worsen urinary incontinence. Medications such as diuretics or supplements that have diuretic action (e.g. dandelion, parsley, juniper, and hawthorn, to name a few) should be discontinued if possible as the polyuria induced by these treatments will often worsen urinary incontinence.
Pharmacologically, increasing dosage of treatment may be effective or combining estrogen with a sympathomimetic, although there is evidence that this may not be as effective as once thought. In patients that fair pharmacologic therapy, other therapies include surgery, urethral bulking, and placement of a hydraulic urethral occluder. Urethral bulking involves injection
of an agent submucosally in the proximal urethra via cystoscopy. It is thought to create artificial urethral cushions improving urethral closure (coaptation). It
may also function as central filler volume increasing length of smooth muscle fibers and closure power
of internal urethral sphincter. There is currently only 1 veterinary specific urethral bulking agent (CellFoamTM, BioChange). Historically, glutaraldehyde cross-linked collagen was used, but has been withdrawn from market. (6) A study with polydimethylsiloxane has promising results (Bartges JW. Personal observation. 2017). Artificial sphincter/urethral occluding device is similar to

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