Urinary incontinence is the inability to control urination (weeing). It is quite common in older female dogs, particularly those who have been spayed, however it can occur at any age and in any sex for a variety of different reasons.
Urethral sphincter mechanism incompetence
The most common cause of urinary incontinence in dogs is known as urethral sphincter mechanism incompetence (USMI). It is caused by a weakness in the urethral sphincter which controls when an animal urinates. The most common signs of this condition are a wet patch after the dog has been lying down. It is rare for dogs with this condition to dribble when walking around.
Any dog can develop USMI but there are several things that can make a dog more prone to it:
- being female
- being spayed
- being overweight
- being a medium to large dog
- having a docked tail
- having an underlying condition which causes excessive drinking (e.g. diabetes or kidney disease) as this means the bladder is fuller and increases the pressure on the weak urethral sphincter
How is USMI diagnosed?
The diagnosis of USMI is often based on age, clinical signs and ruling out other causes or underlying diseases such as urinary tract infections, and conditions which cause excessive drinking and urinating (e.g. diabetes, kidney disease, liver disease).
This will usually involve a minimum of a urine sample and a blood test. Other tests which may be advised include:
- ultrasound examination of bladder and urinary tract
- x-rays of the abdomen, pelvis and spine
- cystoscopy (passing an endoscopic camera up the urethra into the bladder)
How is USMI treated?
In most cases USMI responds well to medical treatment.
There are two main types of medication used, and they can be used together in cases which do not respond to either one alone. One acts to strengthen the urethral sphincter and the other is an oestrogen-based product which helps to counteract the effect of neutering on the urethral sphincter. Both are oral medications.
In rare cases, surgical management is required, often repositioning the bladder further forward so that less pressure is placed on the urethral sphincter. Medical treatment may be necessary post-surgery as surgery alone does not always resolve the problem.
What is the prognosis for USMI?
USMI may, in some cases, be cured by surgical management but if medical management is chosen, treatment will be lifelong. The treatments do not have significant long-term side effects, however, so most dogs will do very well and it will not impact their quality of life or lifespan.
What are other causes of incontinence?
There are many potential causes of incontinence in dogs. Any disease that causes excessive urine production can look like incontinence, even if the dog is not completely unable to control when they urinate. Anything that causes damage to the nerves supplying the bladder can potentially lead to incontinence (E.g fracture to the pelvis, slipped disc, spinal arthritis).
Common causes of incontinence in young animals include:
- ectopic ureter – the ureter doesn’t enter the bladder but goes straight to the urethra meaning the dog has absolutely no control over its urination. This usually leads to continuous leakage.
- abnormalities in development of the bladder, urethra or vagina – very small bladders, wide or short urethra or abnormal vagina can all lead to urinary incontinence.
Other common causes in older animals include:
- prostate disease – this can affect male dogs, whether neutered or not.
- bladder storage disease – this can lead to incontinence when the dog is excited, and also frequent urination through the day