Jenny doesn't feel good.

Jenny started to have accidents in the kitchen last week. It was driving me nuts, I couldn't figure out why she would backslide so bad. The first time she did it was when my neighbor brought her new puppy over, so I thought she was just jealous or something. But she kept doing it even though she goes outside constantly. Then a couple days ago she started whining, especially in the morning and she would pace and wind in and out of the curtains on the patio door. I watched her when she went out and she probably squated to pee 15 times in less than 10 min. Took her to the vet today and she has a bladder infection. So shes on antibiotics and hopefully will feel better soon, but after we left the vet I got to wondering, what caused it. Does it just happen or does something cause it? Can it be prevented? The vet did do an ultrasound, but I don't know why. I didn't find out they even did one till I read my receipt after we left. Their office is very chaotic right now, they had a fire in their main building so until spring they are working out of a very cramped, tiny office that they usually only see cats in. It's called their Cat Care Clinic. I don't have cats so have no idea what that is exactly, but it's tiny and we didn't spend as much time discussing things like we usually do.