Bladder infection?

[RhndLev@cs.com]

Does anyone know if horses can get bladder or kidney infections?  Generally, 
my mare's a go-go-go kind of horse.  However, she has become increasingly 
balky over the last week and a half, and has been stopping to pee multiple 
times on short rides (six miles or so).  Yesterday, on a 12 mile ride, she 
stopped to pee five times, and I was constantly having to leg her on to get 
her to move.  She let other horses PASS HER!  Also, she seemed uncomfortable 
and kept talking to me, grunting, lifting her back, charging into 
transitions.  I finally clued in that she was not just being difficult and 
got off and walked next her the last couple of miles.  She's a Tennessee 
Walker and has a huge walk, but I was having to talk to her and coax her to 
keep up with my big butt walking.  It really seems like a bladder infection, 
but I don't know if horses can get them.  Also, if they can get them, what 
kind of a recovery time are we looking at once she starts antibiotics?  
There's a ride this weekend we were supposed to go to, but I'm not going to 
take her if she's even a little uncomfortable.

Rhonda