Grace, the cranberry was very useful - my vet said about 50mg a day for about a month.

However, Oscar was also on antibiotics for a month to get the very stubborn infection cleared up! The crystals went away almost immediately (there were very few), but he still had the blood in his urine for another 3 - 4 weeks. Poor baby!

In case it is of help to others I will give a few more details here:

The vet figured Oscar had 'idiopathic cystitis', which is mostly due to stress. Oscar had been wild for the first 2 1/3 -3 years of his life, and he had adjusted very well to being indoors and a total sucky boy! However, this infection flared up several months after Cole came to live with us. Oscar and Cole got along great - but as the vet pointed out, even GOOD stress is still stress.

That is why Oscar is on Feliway to this day - he wears a really stretchy collar, and gets a shot a day in it. (He is down from 2 - 3 shots several years ago). The vet suggested trannies - but thanks to Pet Talk, I had heard of this natural alternative, the vet went for it, and all is well!

More prayers that Decker is fine soon. Sometimes the anti-b's just take a while.