Matilda had never urinated or defecated in the house. But Ellie found her dog curled up under the dining room table, looking quite sheepish, and the dog’s bed full of urine. Ellie did her best to comfort Matilda; she could use some comforting words, too, as concerns surface about possible health problems in her 9-year-old pet.

Matilda seems to be dealing with urinary tract incontinence. This means she is not able to hold her urine overnight.

This is a fairly common problem in older dogs, with females showing a higher incidence.

The underlying cause of urinary incontinence can involve a decrease in tone to one of the two urethral sphincter muscles. Each is under a different type of nervous system control, one voluntary the other involuntary. Controlling the urge to go involves the voluntary urethral sphincter. The involuntary sphincter works unconsciously, during periods of sleep for example. When there is decreased tone to the involuntary sphincter, pressure from increased volume within the bladder can overwhelm the weakened tone and allow urine to leak out.

The key to addressing cases like Matilda’s is to determine if her urinary incontinence is primary. In other words, is it due to a primary decrease in involuntary urethral sphincter tone or is it secondary to another issue?

Dogs that develop urinary tract infections caused by bacteria can, as a result, appear to leak urine. This is a secondary incontinence issue. Then there are other causes in which the involuntary urethral sphincter tone is adequate, but the pressure inside the bladder is increased. This increased pressure within the bladder then overcomes the sphincter tone and urine leaks out. This occurs most commonly as a result of increased urine volume, which in turn occurs from increased fluid intake.

Increased fluid intake can be physiologically normal if, for example, your dog has had a very strenuous day and needs to replace fluids lost during exercise. If they take in a meal that is high in electrolytes, sodium in particular, their intake of fluid will correspondingly increase. There are also diseases that cause a significant increase in fluid intake and, thus, urine volume. Kidney disease, diabetes mellitus, diabetes incipidus and hyperadrenocortisism are all associated with increases in fluid intake.

Obviously, the key in Matilda’s case is whether she has primary or secondary urinary incontinence. Physical examination with blood and urine testing should help provide an answer. If she does have primary urinary tract incontinence, there are medications to increase involuntary urethral sphincter tone and curb the leaking.