Sensitivity test is when they let it sit and grow the bacteria and see what antibiotic fight best against it. My Myra had a bladder infection that was determined after an ultrasound. We did numerous cultures/sensitivity tests and numerous antibiotics. (after each culture, it was something different) I shaved her backside down to help not contaminate the cultures. I've had her on D-Mannose for about a month just to make sure I've got her finished after such a long bout. Our issues started back in Sept!
p.s. After such long bouts with antibiotics, it does mess up the gut so keep that in mind!
p.s.s I also started wiping her after her pees, cause she's a very low squatter. It's all routine now
& also agree with Angela, they don't seem to keep them on the antibiotics long enough at first and sometimes that's why the re-occur
p.s.s.s. and some dogs have issues with their vulva's (there is a name for it but for the life of me I can't remember what it's called) and they tend to keep a little urine caught in the wrong spot and it makes the UTI's re-occur