I am fortunate to have a vet who respects my dislike of anti-bio-tics. She ran tests on my 18 year old cat's urine to find which specific bacteria/crystals caused his distress. She suggested I buy Trader Joe's Cranberry extract, and give my cat a half a tablet crushed up food mornings and a half in evenings. One week later, his urinary pH was back to normal, without bacteria, and no crystals. I'm assuming this would work only for certain kinds of distress, and DEFINATELY not if there's already a blockage....I also would not continue the cranberry full time, as it affects acid-alkaline balance.
My cat was diagnosed with fleine lower urinary disease. She was developing struvite crystals. Vet had her on antibiotics and special food. Her eyes looked dull and her coat looked dull. I did some research and now she takes 6 drops of cranberry extract which dissolves the crystals and she eats human grade ingredient cat food. I haven't had a problem in 6 years.