We have faced the same issue. There are two different treatments... one is with Proin, and the other is using an estrogen supplement. My excellent veterinarian has recommended the estrogen treatment (DES) as being most often effective and less side effects on dogs. However, my female dog did not respond to this treatment. The Proin is effective for my dog but it's side effect is possible elevated blood pressure. If you start your dog on Proin, its blood pressure should be tested initially to make sure the dosage doesn't negatively impact it. Proin has worked well for us... and yes, my dog does not like the large chewable tablets ... I solved that issue long ago by buying a small ceramic mortar and pestle at a kitchen store and grind the pill up for each meal. My dog gets breakfast and dinner, which makes giving her her half a pill twice a day easy. This web site is probably one of the better ones for information on K9 urinary incontinence:
WebMD