Proin and UTI? HELP Needed here-thanks

I got a question. I got my dog teased for a UTI and the vet did in-office test and it came back clear, so we went on and put the dog on Proin. I cut the pills downin forths, and they still work.

Question: If my female dog gets a UTI while on Proin, how will I know? Also if she gets a UTI will it harm her whle being on Proin since it would seem to keep the bladder tighter? I might not be clear on how Proin works. The vet said it was an antihestimine, which seems odd to me that it was taken off the market for humans.

My dog also died last year from either Proin or Amoxicellin, I am hoping that it was the Amoxicellin. I am being cautious with the Proin.