So I decided Millie would just have to stay indoors as much as possible till Friday after Christmas, 5 days. I mopped the kitchen floor to have it extra clean, and thought there would be no problem, she could just pee on the kitchen floor and I'd clean up. Sounded like a good plan. I didn't think it would bother Millie, because she has taken to peeing in the tile sometimes anyway this past 6 months, she's an older dogger. Of course Milllie had no way to know she was expected to pee on the floor all the time, so in retrospect I assume she was holding it as long as possible hoping to be let out as she's always been.
On Friday she was back to normal yard privileges as her paw had stayed good. Full weight bearing, no signs of blood, she didn't seem to know there was anything wrong. I thought we'd handled it. Then Saturday before lunch I noticed her drink from her bowl and then pee on the floor. The urine looked fine but there were 5 drops of blood sprinkled where she walked away after finishing. I could tell it was urine, not her foot, and immediately realized, I must have caused her to get a UTI by not letting her out as often as she wanted. I was trying to avoid getting her foot infected (so we didn't wind up at the emergency vet on Christmas) and instead she got a UTI.
So she had to go to the vet Saturday and is on amoxicillin. She seems fine and happy, as energetic as usual. I guess I don't have to worry about an infected paw now that she's on the amoxicillin. I am really bad at predicting behavior in pets. I thought she would just pee as needed, but she must not have. I was so worried that she's too old to have surgery to fix her foot if it didn't heal, but I never even considered the possibility of UTI.