Dr. Brad Green, a veterinarian at Puget Sound Veterinary Referral Center in Tacoma, answers questions around this week's topic of urinary incontinence.

Question: A reader has sent us a question about her 8- or 9-year old spayed female dog who has become incontinent. She says she is spaniel size and otherwise healthy. It is a battle to feed her any medicines. What is urinary incontinence, and what are the causes?

Answer: Urinary incontinence is the involuntary leaking of urine. Usually, the dog is unaware of the leaking, and it often occurs when the dog is sleeping. Incontinence is different from inappropriate, voluntary urination.

Urinary incontinence can be caused by a dysfunctional urethra. (The urethra is the tubular structure through which the urine from the bladder is eliminated from the body.) Poor function of the urethra is usually caused by weakness of the muscles of the urethra. The reasons for this are poorly understood, and the syndrome has been referred to as urethral incompetence.

Other causes of incontinence include neurological diseases, urinary tract infections, bladder stones and anatomical abnormalities. Those abnormalities include disease of the prostate (males only), cancer of the urethra or bladder and ectopic ureters, which is when. the tubular structures, or the ureters, that carry urine from each kidney to the bladder are in abnormal positions.

Question: What underlying health problems can cause a spayed, female dog to become incontinent?

Answer: In an adult, spayed, female dog, incontinence is usually due to urethral incompetence and is associated with aging. Less commonly, neurological dysfunction and cancer of the urethra or bladder are to blame, particularly in older dogs. Additionally, previously asymptomatic ectopic ureters occasionally can become apparent in middle age when urethral muscle tone decreases.

In some dogs who develop incontinence, it is actually a problem of increasing urine volume rather than a change in urethral muscle tone. This change can cause an otherwise continent dog to become incontinent. Common diseases that cause an increase in urine volume are diabetes, hyperadrenocorticism (Cushing's disease), kidney dysfunction and liver dysfunction.

Question: Does spaying a female dog make her more vulnerable to incontinence?

Answer: There is significant debate surrounding this question as study results have been contradictory. However, there is evidence that early spaying (under 3 months of age) is a risk factor for developing incontinence. There is not decisive evidence that spaying after 6 months increases the risk of developing incontinence.

Question: How might age and/or breed factor in?

Answer: In young dogs, ectopic ureters are an important diagnosis to consider. In older dogs, cancer becomes a concern.

Urinary incontinence due to urethral incompetence does not affect any particular breed more commonly than others, but breeds known to be more likely to have ectopic ureters include Siberian huskies, miniature and standard poodles, Labrador retrievers, Newfoundlands, fox terriers, West Highland white terriers, collies and Welsh corgis.

Question: Are there other symptoms I should look for that might help me or my vet determine what is wrong, such as fluid intake, weight gain or loss?

Answer: Report all changes to your dog's urination, drinking, and eating habits to your veterinarian. It is also important to note any changes to the color of the urine.

Collecting a morning urine sample also can be helpful to your veterinarian, but for some testing it is best for the urine sample to be obtained directly from the bladder with a needle, which can be done by your veterinarian.

Question: Is incontinence something for which I need to visit the vet?

Answer: Absolutely. Urinary incontinence can lead to a poor quality of life for both owner and pet. It also can lead to other health problems. In most cases it is a condition that can be effectively treated.

Question: What will be done if I take my dog to my vet for this problem?

Answer: The first line of testing will always include physical examination, a urinalysis and urine culture. If there has been an increase in the volume of urine produced, an increase in the amount of drinking, or if the urine is dilute, blood work also may be performed. Radiographs (x-rays) may be recommended in some cases.

If the dog is young and the initial testing fails to identify a cause, cystoscopy -- an investigation of the urinary tract with a special camera -- can be performed to identify ectopic ureters. In an older dog, an ultrasound of the bladder may be recommended.

Abnormal findings with any of this testing or the physical examinations may lead your veterinarian down a different diagnostic and therapeutic path.

If the problem is found or assumed to be urethral incompetence, then medications are usually prescribed. Medications alone are successful in 70 percent to 80 percent of cases. Fortunately, for the dog in question who is difficult to medicate, one of the commonly used medications can often be given as infrequently as once a week. When medications are not successful, there are surgical implants that are more than 90 percent effective.

In patients with ectopic ureters, a relatively simple surgery has been developed to fix this problem, although medications are still required in some dogs.

Dr. Brad Green

Dr. Green runs the Internal Medicine Service at Puget Sound Veterinary Referral Center in Tacoma. He received his veterinary degree from Ohio State University and completed a residency in internal medicine at the University of Wisconsin. Green's particular interests within the field of internal medicine include endocrinology (diabetes, Cushing's disease, thyroid disease), endoscopy, liver disease, urinary disease and pulmonary disease. In addition to the Internal Medicine Service, Puget Sound Veterinary Referral Center houses Emergency & Critical Care, Neurology, and Surgery Services.

Read our past Q&As:

Veterinary Q&A: Incontinence in dogs
Veterinary Q&A: Hanging tongue syndrome
Veterinary Q&A: Bad breath in dogs
Veterinary Q&A: How much is too much exercise for my dog? Part 2
Veterinary Q&A: How much exercise does my dog need? Part I
Veterinary Q&A: A killer called bloat
Veterinary Q&A: Initial care for new puppies
Veterinary Q&A: Knee problems in dogs
Veterinary Q&A: Flea-control treatment
Veterinary Q&A: Bearded dragon lizards
Veterinary Q&A: Vaccinations for indoor cats
Veterinary Q&A: Lumps and bumps
Veterinary Q&A: More on aging dogs and arthritis
Veterinary Q&A: Aging dogs and arthritis
Veterinary Q&A: Puppy and geriatric exams
Veterinary QA: What dogs can safely chew
Veterinary QA: Why does it cost so much to clean a dog's teeth?
Veterinary QA follow-up: More on cleaning a dog's teeth
Veterinary QA: When to spay or neuter

Do you have a question about pet health? Ask now! We'll pose some of your questions to a local vet in an upcoming post.