Managing urinary incontinence in cats

Introduction

Urinary incontinence is defined as the involuntary loss of urine through the urethra. It is generally characterised by an intermittent or continuous dripping of urine, which may or may not be accompanied by episodes of normal urination or nocturia. Urinary incontinence is estimated to be much less common in cats than in dogs, representing just 4–5% of all cases of lower urinary tract disease.^1-3 This explains why there is scant data regarding the aetiology, diagnosis and treatment of this process compared with the information available for dogs.

In any event, when it does occur, urinary incontinence in cats can have a profound negative effect on both the patient’s and owner’s quality of life.⁴ As such, vets must be aware of the common causes of urinary incontinence in the cat.

Main causes of urinary incontinence in cats

Urinary incontinence in cats can be caused by congenital or acquired disorders of the ureters, bladder, spinal cord and hypogastric, pelvic or pudendal nerves or urethral sphincter mechanism incompetence.

Therefore, feline urinary incontinence can be classified according to different criteria, such as the location of the lesion, its congenital or acquired nature and whether it is of neurogenic origin.^3,5

Although there are no major epidemiological studies into the causes of urinary incontinence in cats, over 40 congenital or acquired disorders (affecting the spinal cord, urinary bladder, urethra, and reproductive tract) have been reported as potential factors.³

Some authors believe that most cases of urinary incontinence in cats is due to ectopic ureter or urethral sphincter incompetence, usually of a congenital origin and often associated with other malformations of the genitourinary tract.^2,6 However, two recent studies^1,3 reported that spinal cord problems, of various origins and at different levels, are the most frequent cause (40–48%) of incontinence.

Other causes include diseases of the urethra, bladder and ureters.^1,3 Interestingly, a significant percentage (34%) of the cats in one of these studies had non-neurogenic incontinence secondary to urethral obstruction, while none of the subjects had incontinence due to sphincter incompetence or ectopic ureter.¹

Another distinction between cats and dogs is that sphincter incompetence in cats is usually of a congenital origin, whereas in dogs it is usually acquired.^3,4 Feline urinary incontinence has also been described as a sequela (> 9%) of a urethrostomy, especially when carried out in prepubic patients.⁷

Diagnosis

The initial diagnostic approach to cats with incontinence should include a complete anamnesis, physical examination (checking whether the bladder is empty or full and if manual emptying is possible), neurological examination and urinalysis.

The next step is to select the most appropriate imaging tests for each patient according to aetiological suspicion:

• Cystography: indicated whenever an abnormal bladder position, size or shape is suspected.
• Ultrasound: suitable if masses or stones are suspected.
• Cystography, excretory urography or a computed tomography (CT) scan may be used if an ectopic ureter is suspected.
• In patients with incontinence of a neurogenic origin, plain X-rays (or failing this a CT or MRI scan) can reveal the origin of the problem (disc spondylosis, fractures, vertebral stenosis, etc.).⁵
• Urodynamic studies are typically only available in a few referral centres and usually reserved for cases in which all prior efforts have failed to reach a diagnosis and establish the right treatment plan.

Treatment and prognosis

There is no conclusive evidence of the efficacy of the various treatments for feline urinary incontinence, probably because of its low prevalence. In general, the medical management of sphincter incompetence is considered ineffective, while its surgical resolution is also of limited value.^2,7

Disease prognosis is potentially worse in cats with spinal cord disorders than in those with incontinence secondary to a vesical or urethral problem.³ In fact, the prognosis for cats with incontinence secondary to urethral obstruction is good, so long as the appropriate interventional procedure is performed.¹

Conclusions

Besides being much less frequent than in dogs, urinary incontinence in cats presents specific aetiological characteristics that differentiate it from urinary incontinence in dogs. These differences may explain, at least in part, why standard medical treatments for dogs are usually ineffective in cats. Whatever the case may be, a good diagnostic approach is key before telling owners that the problem cannot be treated, because treatment is available for cats with incontinence secondary to urethral obstruction, for example, and the prognosis is good.

References

1. Mérindol I, Dunn M, Vachon C. (2021). Feline urinary incontinence: a retrospective case series (2009-2019). J Feline Med Surg. Online ahead of print.

2. Fournet A, Maurey C, Decambron A, et al. (2021). Treatment of urinary incontinence in a cat with genitourinary dysplasia using an urethral sphincter occluder. J Small Anim Pract; 62: 391-396.

3. Lonc KM, Kaneene JB, Carneiro PAM, et al. (2020). Retrospective analysis of diagnoses and outcomes of 45 cats with micturition disorders presenting as urinary incontinence. J Vet Intern Med; 34: 216-226.

4.  Wilson KE, Berent AC, Weisse CW. (2016). Use of a percutaneously controlled hydraulic occluder for treatment of refractory urinary incontinence in three female cats. J Am Vet Med Assoc; 248: 544-551.

5. Silverman S, Long CD. (2000). The diagnosis of urinary incontinence and abnormal urination in dogs and cats. Vet Clin North Am Small Anim Pract; 30: 427-448.

6. Holt PE. Gibbs C. (1992). Congenital urinary incontinence in cats: a review of 19 cases. Vet Rec; 130:437-442.

7. Eayrs MK, Moores AL. (2021). Management of incontinence following pre-pubic urethrostomy in a cat using an artificial urethral sphincter. J Small Anim Pract; 62: 604-607.