The U.S. Food and Drug Administration (FDA) has approved the first drug for treating urinary incontinence in female dogs. The drug, Incurin (estriol), is indicated for the control of estrogen-responsive urinary incontinence in spayed female dogs.

Hormone-based urinary incontinence (involuntary urine leakage) is a common problem in middle-aged and elderly spayed female dogs. The pet can urinate normally, but they leak urine while resting. Frequently the dogs are not aware that they are leaking urine. Physical examination and blood and urine tests are usually normal in these pets. Hormone-responsive incontinence can occur months to years after a dog is spayed.

The FDA said Incurin (estriol) is a natural estrogen hormone, which helps to increase the resting muscle tone of the urethra in females and can be used to treat female dogs with urinary incontinence due to estrogen depletion.

The agency cited a placebo-controlled field study of 226 spayed female dogs, in which a greater percentage of dogs treated with Incurin were improved (fewer or no incontinence episodes) compared to dogs treated with placebo. Incurin was shown to be effective for the control of estrogen-responsive urinary incontinence in spayed female dogs 1 year of age and older.

The most common side effects associated with the drug treatment included a loss of appetite, vomiting, excessive water drinking and swollen vulva.

Incurin is manufactured by Merck Animal Health and will be made available at a later date, the FDA said.