My Speckles has had several UTI's and she gets a Baytril shot and Baytril pills and with her, it took at least 4 days before I saw any results. Be patient and if you don't see any results within that time, take her back. She may need some other kind of meds. There is also something called a Sensitivity Test and the urine is tested to see which medication will work best.

Prayers going out to your sweet girl.