I see your answers came through on a different question. One thing I would try is lighting the back yard good for her so she isn't scared of the dark. Some dogs don't like going out in the dark especially if they are experiencing any loss of vision. Some dogs suffer from PRA. Read about this here:
Lighting the area up really well may help encourage her to go out on her own. You might also feed her earlier and only give a small amount of kibble right before bed and take up all water at around 4pm. This will give her the opportunity to urinate before going to bed. I also want you to start taking her out at least twice between 5 and bedtime. Be sure she has plenty of fresh water before that. Try to take her outside at the same time each day. Dog tend to be able to judge time and if you do it the same time she may hold her urine until the next scheduled "potty time".
Be sure you are cleaning with a good high quality enzymatic pet odor remove. Be sure you let it soak in as long as the urine did so it reaches all the urine to break down the protein which is what causes the odor. As the odor fades, dogs tend to come back to that area and urinate again, so removing it completely helps stop them from urinating there again since they won't be drawn to it.
I would also get a child gate to put at the top of the stairs to prevent her from going downstairs on her own. Since she is letting you know she needs to urinate., keeping her with you a little longer while you make your way downstairs may help solve the problem as well. I'd keep a leash at the top of the stairs as well so she can't rush down the minute you open the gate or place the gate at the bottom of the stairs but then she might urinate in that area. Preventing the behavior will help stop the habit as well.
If you haven't had her into the vet, you may want to take a urine sample into the vet to ensure she doesnt' have a urinary tract infections. Common symptoms of a urinary tract infection are frequent urination, dribbling urine, blood in the urine, squatting frequently to urinate, strong odor to the urine, inappropriate urination and straining to urinate as well as an increase in fluid intake. A dog with a UTI does not always show all the symptoms and typically displays 2 or 3. If your dog is displaying 2 or more of the above symptoms then you should have her seen..
Professional cleaner often do the job properly, but not only does it need to be cleaned properly but also break the dog's habit of going there. Preventing it is the only way to stop that. Now if you are downstairs most of the time during the day, it may be a case of her being unable to hold it long enough combined with not wanting to go outside in the dark. This would be a form of incontinence. One drug frequently prescribed is phenylpropanolamine which you can read about here:
This medication helps when a dog has a weak bladder sphincter and strengthening it can allow a dog better control of the bladder and maybe allow her to hold it long enough to wait for you to get downstairs.
Another solution would be to create a sod patch in the house where she could urinate if she can't get outside or doesn't want to go out. Many owners with spayed dogs or tiny dog that tend to not want to go out in the rain and cold opt for this idea to help save their flooring. You take a large pan like a kitty litter pan or even a baby swimming pool. You create a platform frame with wire on top. Place newspaper or other absorbent material such as wood shavings under the platform and place sod on top of the wire frame. Since it is grass, your dog will go on it. You can remove solids and can spray the urine so it moves through and down into the absorbent material underneath. This lets you use the same piece of sod for a while before needing to replace it. You do need to replace the material under the platform.
For a small dog, it isn't so big of an issue to have a small area for the dog. The fact that it is grass also keeps the dog knowing that grass is where she is supposed to go. When she urinates on the sod, you would rewqrd her with a tasty hot dog treat which you should also do when she eliminates outside. You need to reward her as soon as she goes and not wait. She has to make the connection between the treat and urinating outside or on the grass inside. That helps her develop a substrate preference (what material she likes to urinate on). I have a male that somehome thinks plastic is where he goes. I suspect his first owners used pee pads which have plastic on them.
I hope this information is helpful to you. If you would like any additional information or have more questions please don’t hesitate to press the reply to expert or continue conversation button so I can address any issues you still have . If you do find this helpful, please take this opportunity to rate my answer.