If she is spayed this might be due to lack of estrogen. Its an issue that does sometimes show up in spayed females.
In dogs that are not spayed a urinary tract or kidney infection might be the issue.
There are meds to help with the problem if its incontinence or an infection.
In the meantime while you get with your vet I suggest a diaper for her while she is inside so that you just have to keep her clean instead of washing up where ever she may have had an accident.
You can use disposable baby ones if you can find a size to fit her - just cut a tail hole.
Or you can use a 'sanitary belt' for dogs in season and just use an incontinence pad on it to catch the urine. Some pet supply stores carry the belts or 'bitches britches' or something similar you fit a pad in.
Here is one site that talks about the problem
http://www.auntjeni.com/incont.htm
Hope this helps you!

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