Phenylpropanolamine acts by increasing the muscle tone in the muscles of the urethral sphincter. It is usually very effective in controlling female incontinence in dogs, and is the first line treatment for it. The only side effects that may occur is increased excitability and restlessness. Decreasing the dosage gets around this problem.

Another older treatment was the use of the synthetic female hormone Diethylstilbestrol. If Phenylpropanolamine fails, then DES might be tried. It works by causing the hormonal sensitive tissue to swell, and giving something for the muscles to push against to clamp off the urethra. DES was linked to cervical cancer in daughters of women who took the drug during pregnancy, and has largely disappeared from human medicine. It may be difficult to obtain.

Merck Index