Diagnosing & Treating Urinary Incontinence in Dogs
Sponsored by PRN® Pharmacal
Urinary incontinence has a reported prevalence of ≤20% in spayed female dogs,1,2 with lower prevalence in intact female dogs and male dogs.1,3 Normal urinary control is a complex process, requiring coordinated function between the sympathetic and somatic nervous systems, which govern urine storage, and the parasympathetic nervous system, which governs urine voiding.1 Distinguishing true incontinence from inappropriate conscious voiding is essential for accurate diagnosis and effective management.
Diagnostic Approach to Urinary Incontinence
The diagnostic approach to urinary incontinence begins with the collection of a full, thorough history from the client. Clients should be asked whether their pet has experienced any changes in water intake and/or urine volume, the onset and course of signs as perceived by the owner, and timing of urine leakage (rest vs activity), if present. Direct observation or video review of incontinence and voiding behaviors can be helpful.
A complete physical examination, including bladder palpation and rectal examination with urethral palpation, and a complete neurologic examination should be performed.
An appropriate initial diagnostic investigation should also include screening for underlying systemic or urinary tract disease, as these conditions can either mimic incontinence or exacerbate its clinical signs. This may include urinalysis ± urine culture, abdominal radiography ± ultrasonography, and a CBC and serum chemistry profile.
Measurement of postvoiding residual volume (PVRV) can help in determining whether the patient’s condition is a storage or voiding disorder. An increased PVRV (usually >3 mL/kg) suggests a voiding disorder, whereas normal PVRV with incontinence would suggest a storage disorder.1,4 Storage disorders in dogs include urethral sphincter mechanism incompetence (USMI), ectopic ureters (most common cause of incontinence in puppies), and detrusor instability. Voiding disorders include functional outflow obstruction (eg, spinal cord injury), mechanical outflow obstruction, and atonic bladder.
Additional diagnostics and/or referral should be performed or recommended as needed. These can include abdominal ultrasonography, cystourethrogram, or cystoscopy for anatomic or functional evaluation.
Treatment Options for Canine Urinary Incontinence
If a storage disorder is suspected in a spayed female dog, treatment should follow guidelines for USMI, the most common cause of incontinence in this population. Alpha-agonists (eg, phenylpropanolamine) or estrogen compounds are the recommended first-line options for USMI in female dogs.1 Alpha agonists are the first-line treatment of choice for male dogs with USMI; estrogen compounds should be avoided in male dogs.1
Although voiding disorders due to functional outflow obstruction may be managed medically with alpha antagonists with or without skeletal muscle relaxants, mechanical outflow obstructions may require emergency intervention, with specific treatment dependent on the cause of obstruction (eg, neoplasia vs urolithiasis vs trauma).1,5
Proin ER™: A Reliable & Convenient First-Line Option
Proin ER (phenylpropanolamine hydrochloride extended-release tablets) is an FDA-approved medication for the control of urinary incontinence due to urethral sphincter hypotonus in dogs. It is a recommended first-line treatment for USMI, the most common cause of urinary incontinence in dogs.1,3,6 Phenylpropanolamine is an alpha-adrenergic agonist that has been reported to increase urethral tone in dogs.1,7 Proin ER is convenient for pet owners, requiring once-daily administration (2-4 mg/kg PO every 24 hours) of whole tablets (eg, not split or crushed) with food.7
Phenylpropanolamine is effective for USMI and is not indicated for incontinence caused by neurologic disorders or congenital malformations. This medication is not suitable for dogs weighing <10 lb (4.5 kg), as they cannot be safely dosed with the available tablet sizes.7
Adverse effects are mostly dose-related and include GI effects, hypertension, proteinuria, tachycardia, lethargy, UTI, elevated ALP and/or ALT, hypoglycemia, hypercalcemia, increased BUN, bradycardia, and seizures or twitching.1,7 Proin ER should be used with caution in patients with cardiovascular disease, glaucoma, prostatic hypertrophy, hyperthyroidism, diabetes mellitus, hyperadrenocorticism, liver disease, hypertension, and renal insufficiency, as well as in patients receiving sympathomimetic drugs, tricyclic antidepressants, monoamine oxidase inhibitors, and/or halogenated gaseous anesthetics.7 Proin ER may cause increased thirst, and clients should be advised to ensure that ample water is available.7
Prior to initiating therapy, clinicians should measure baseline blood pressure. Repeat measurements should be taken shortly after initiating therapy and any time the dose is increased. In dogs with hypertension or conditions that may predispose the patient to hypertension, blood pressure should be checked at least twice annually.8,9
Conclusion
Diagnosing true incontinence and identifying the underlying cause is key to effective treatment. USMI remains the most common cause of acquired urinary incontinence,6 and Proin ER provides a convenient, effective, once-daily, first-line therapy for most affected dogs. With appropriate patient selection and monitoring, Proin ER can help support improved quality of life for both dogs and their owners.
