older dog, house training help required

I have two yorkies, an 11 year old female and a 5 year old male, both are rescue dogs. My older female has decided it is perfectly ok to do her business anywhere in the house at any time of day regardless if we've just been outside. This dog was not trained when we rescued her 7 years ago and after a considerable amount of time and work she got the message and would only mess if we'd been delayed in getting home. I am retired and therefore home all day most days. After she has done her business on the carpet she will come and tell me. She also asks to go out umpteen times a day, many of which I have to continuously tell her to pee and refuse to bring her in until she has done so. However, we can go out and she'll pee but then 10 minutes later poop on the floor or vice versa. We thought perhaps she had an infection, took her to vet, did urine tests, everything was negative. She does not get up often during the night to go out. She has been on prednisone for irritable bowel syndrome for years and as a result drinks more than a normal dog would. We are accustomed to her asking to go out often. There is no rhyme or reason to her behaviour and I'm at the end of my rope. My other concern is that the other dog will begin the same behaviour. HELP.

Wow, sounds like you have your hands full with some potty issues! I don't know if I will be much of a help, but I know that my perfectly housetrained dog was never the same after going on prednisone. I think it is almost imposible to have a housetrained dog on pred. Some dogs may respond differently than others, but the times my dogs have been on pred, I have had nothing but accidents. I had a dog with inflammatory bowel disease and he was put on pred, but even extremely low doses caused him to pant all day long and urinate all over...he was a great dane, so imagine what we went through It was literally the great lakes at our house!! The other thing I would consider using as a last result are protective pants....aka hot pants etc. I know you have probably seen them around, but they look like underwear for dogs and they are usually used for incontinent dogs or bitches in season. You can put absorbent pads in them , but most dogs wont soil themselves...you do however, need to make sure that you don't leave her for an unreasonable amount of time and expect her to "hold it" with these on. My Mom used diapers on our poodles when I was a kid because they refused to potty train ever (may have been trainer error ) They would never have an accident with the diaper on. I am sure you will get better advice from others...good luck.