Aging Dog Question

I have a 16 yo female Red Healer that has little or no control over bladder. Both back legs are stained from frequent urination. Vet said I needed to bring her in for evaluation before they can prescribe something to relieve incontinence and strengthen the bladder. What is the OB's experience with this - is there some over the counter meds you can pick up? Also, I have heard that in older females estrogen levels can get low and this may affect the loss of bladder control. Estrogen supplements? I understand at 16 we are lucky to have had her and at some point I may have to make the difficult decision but for now, she is not in pain and still has some spring in her step.

Thanks in advance for any information.