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Advances in Veterinary Cystoscopy Highlight: Collagen injections for urinary incontinence

Thursday, February 01, 2007

by Alicia Henderson, DVM, Diplomate ACVIM

Lower urinary tract disease is a common and significant problem in small animal medicine. Transurethral cystoscopy (also termed urethrocystoscopy) is becoming an increasingly important part of the diagnostic evaluation of dogs and cats with recurrent or persistent lower urinary tract disease. Cystoscopy provides information not obtainable through radiographs, contrast studies or ultrasonography as it allows direct visualization of the vestibule, vagina, urethral opening, urethra, bladder, and ureteral openings. Additionally, many recent advances in therapeutic techniques have occurred, expanding its use beyond diagnostic purposes. Specific indications include recurrent urinary tract infections, chronic cystitis, dysuria / stranguria / pollakiuria, tumors of the lower urinary tract, urinary incontinence, hematuria, cystic and urethral calculi, and urinary tract trauma.



Figure 1. Normal view from vestibule

Diagnosis

Recurrent Urinary Tract Infections
Although the majority of urinary tract infections are fairly straightforward, there are multiple factors that can contribute to complicated recurring urinary tract infections. These include disruption of mechanical or anatomic defenses (urinary incontinence, urine retention, urachal diverticuli, ectopic ureters, vaginal disorders), disruption of local antibacterial defenses (calculi, neoplasia), and disruption of immune competence (hyperadrenocorticism, diabetes mellitus, corticosteroid or other immunosuppressive therapy). Cystoscopy is useful for diagnostic evaluation of patients with recurrent urinary tract infection because it allows direct examination for anatomic defects that may compromise host defenses. Furthermore, it permits collection of biopsy specimens for histopathology and microbiologic culture. Cultures of mucosal biopsies obtained via cystoscopy are more sensitive for detection of bacteria and mycoplasma compared to urine culture obtained via cystocentesis.

Feline Idiopathic / Interstitial Cystitis
Both male and female cats frequently suffer from periuria, pollakiuria, dysuria or stranguria. Idiopathic/interstitial cystitis is the most common diagnosis in young cats with signs of lower urinary tract disease; however in some cases cystitis can be difficult to differentiate from a behavioral disorder. Cystoscopy allows observation of submucosal petechial hemorrhages, known as glomerulations, which are supportive of a diagnosis of feline idiopathic cystitis. Conversely, lack of such cystoscopic lesions in cats with periuria may suggest that the inappropriate urinations are behavioral in etiology.

Neoplasia / Granulomatous Urethritis
Transitional cell carcinoma is the most common type of bladder/urethral tumor in dogs and cats. It is most often located at the trigone of the bladder and typically has a characteristic appearance as proliferative finger-like projections. Other types of tumors identified in the bladder include squamous cell carcinoma, adenocarcinoma, leiomyoma, fibrosarcoma, and lymphoma. Cystoscopy is useful for documenting the extent and location of lower urinary tract neoplasia and for obtaining biopsies. Biopsies taken during cystoscopy have a higher diagnostic yield and accuracy than those obtained by traumatic catheterization and cytospin concentration techniques. It is important to differentiate transitional cell carcinoma from granulomatous (proliferative) urethritis which can mimic the appearance of neoplasia but has a more favorable prognosis.



Figure 2. Mass in urethra


Ectopic Ureters
Ectopic ureters (EUs) are the most common cause of urinary incontinence in young dogs. An ectopic ureter is defined as a ureteral opening in any area other than the normal position in the trigone, including the bladder urethra junction, various locations along the urethra, and rarely in the vestibule. Although unilateral EUs have been reported to be more common, bilateral EUs were significantly more common in a recent study. Other congenital abnormalities such as hypoplastic bladder, pelvic bladder, ureterocele, and hydroureter are common in patients with EUs which attests to the importance of careful urinary tract imaging prior to surgery. A diagnosis of ectopic ureters can be made by excretory urography, abdominal ultrasound, cystoscopy, computed tomography or a combination of these diagnostic procedures. Cystoscopy is the procedure of choice for assessing cases with suspected ectopic ureters and is superior to radiographic contrast studies or surgical assessment. It allows determination of the termination point of the ectopic opening(s) which is important in order to obtain the best surgical outcome for the patient.



Figure 3. Ectopic ureter in urethra


Hematuria
Causes of hematuria include infection, cystitis, urolithiasis, neoplasia, prostatitis, coagulopathy and idiopathic renal hematuria. Cystoscopy allows the source of gross hematuria to be localized to the genital tract, urethra, bladder, and right or left kidney or ureter. Localization of upper urinary tract hematuria can be determined by direct visualization of gross hematuria from the ureteral orifice. This approach is more accurate than attempting to predict the source of hematuria based on when blood is noted during voiding.

Therapeutic Techniques

Bulking Agents for Urinary Incontinence
Canine urinary incontinence is a common problem in veterinary medicine and can be extremely frustrating for clients. The most common acquired cause of incontinence, affecting 5% to 10% of spayed dogs, is primary sphincter mechanism incompetence (PSMI). The cause of PSMI is likely multifactorial including hormone imbalances, genetics, obesity, age-related changes in urethral musculature and position of the neck of the bladder. The main historical finding is urinary leakage during sleep or rest. Medical treatment involves the use of phenylpropanolamine (PPA) which stimulates alpha-adrenoreceptors and increases urethral tone. Unfortunately, this drug needs to be given two to three times daily and side effects include restlessness, anxiety, hypertension and tachycardia. Therefore it is contraindicated in patients with cardiac disease or hypertension. Estrogens may also be used in the treatment of PSMI. These hormones are thought to increase the number or sensitivity of alpha-adrenoreceptors in the urethra. Additionally, they may help to improve blood flow and collagen formation in the internal urethral sphincter. Due to the possibility of bone marrow suppression, the lowest possible dose of estrogen should be used. Most dogs become continent when treated with PPA or estrogens, however some cases are refractory to medical management. The submucosal injection of urethral bulking agents such as collagen is often successful in resolving incontinence in those patients that fail standard medical treatment or patients that cannot tolerate adrenergics or estrogens. Even in dogs in which standard medical treatment results in continence, collagen injections could be considered as an alterative to lifelong medication in a young patient. Garden State Vet Specialists is now offering endoscopic urethral collagen injections for female dogs. In this procedure, periurethral submucosal injections administered through a cystoscope result in narrowing of the urethral lumen, thereby improving urethral closure pressure. In a recent study, 68% of dogs treated with this method attained full urinary continence and an additional 25% of owners reported a significant improvement.

Urolith Removal
Stone baskets may be used to remove uroliths from the lower urinary tract provided the uroliths are smaller than the dilated urethra. This technique may be safely used to remove uroliths that will not readily pass during voiding urohydropropulsion.

Stricture Dilation
Urethral strictures in dogs and cats may occur secondary to urethral trauma from catheterization or urolithiasis. Strictures can be detected via cystoscopy and treated with dilation over guidewires or balloon dilation catheters. Cystoscopically placed guidewires may also facilitate placement of urethral catheters or stents to provide short term bladder drainage in patients whose obstructive lesions are not surgically correctable.

Summary

Cystoscopy has proven to be a highly effective, minimally invasive technique for diagnosis of lower urinary tract disease in dogs and cats. In many respects, cystoscopy provides enhanced examination of the urinary system compared to surgery or radiographic contrast techniques. It should be considered the primary tool for any chronic or acute urinary tract disease that is difficult to diagnose or resolve. Furthermore, exciting new advances such as cystoscope guided periurethral collagen injections offer new options for veterinarians and clients managing a frustrating condition. If you have any questions regarding cystoscopy or periurethral collagen injections, please do not hesitate to call me at Garden State Veterinary Specialists, 732-922-0011.


This article is for informational purposes only and should not be used as a substitute for the professional advice of your veterinarian.

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