Proin has side effects that can be quite dangerous and uncomfortable for your pet. They are:
Rapid heart rate
Elevation in blood pressure
Appetite reduction Pale gums
Difficulty in urinating
Further, Proin will not work if it is not due to incontinence due to aging hormonal imbalances. From what you describe though, that is probably what is going on.
Colloidal silver should help with this condition, especially if it is caused by a urinary infection as it will kill the pathogens. Actually this is wonderful for your pet's overall health and will give her the vim and vigor she once had as a puppy.
Other herbs that will help:
CORNSILKLook for fresh (not dried) silk threads. These can be found in organic food stores, health food stores, or clipped directly from ears of corn, preferably organically grown. Cornsilk is safe for long term use. It may be combined with couchgrass and echinacea; this combination will help with inflammations or infections of the urinary tract. Another useful herb to try for treating incontinence is called UVA URSI. For a medium dog (~70 lbs) try about a teaspoon or so, or if you buy in capsules form, follow the label directions, using half the recommended dosage for humans. A lot of "natural" and herbal remedies are very individualized, and the amount needed by your dog may be different from the amount needed by my dog.
Another herbal mixture you can try is 2 parts horsetail, 1 part agrimony, and 1 part sweet sumach. This information is taken from a human herbal book, which recommends brewing this mixture as a tea and drinking 3 times a day. For dogs, we would either add to drinking water or mix into food. Unless of course they are willing to drink it. You might want to go to a health food store and see what other herbs you can find for incontinence.
Lastly, I highly recommend feeding a natural, home prepared diet, consisting of fresh, raw, human-grade meats. Cut all grains from his diet.