Pick your brains please

We have had a pug in rescue for quite a while, and we have been stumped. Basically, he seems to have the symptoms of a stone, yet nothing shows up when we test for them. He has had reoccuring UTI's, and this last time, the acidity was very high and his bladder was inflamed. It's been two weeks, and we retested him again, and the levels have come down but it's still very concentrated. The foster home feeds them high quality grain free food and has been flooding his food with water. He had tried raw previously but this pug, and one of his other dogs didn't tolerate it very well. It's frustrating because until we can get to the bottom of it, we can't adopt him out.

Our vet did consult with a specialist and they said that there are some stones (I forgo the name) that may not show up in x rays and MRI's. I hadn't heard of this but was hoping someone else might have some ideas to try or look for.

Struvite stones are usually the ones that don't show up. We had an adopted dog develop a blockage that didn't show up on X-ray and when we flushed his system, it was struvites.

I'm going to email you some information on struvites and calcium oxalates. We have a very similar dog in care right now who consistently gets a high pH as soon as we stop using cranberries.

I would first take this dog off of kibble and put him on canned if he doesn't tolerate raw and cooking for him isn't an option. Continue to flood his food and think about adding 6 cranberries per meal until the pH comes down. We keep pH test strips in the rescue to monitor pH with these dogs.

I don't have much experience to share. Our only experience has been with struvites/triple phosphate crystals. I believe they diagnosed Bruno based on his pH count and microsopic exam of his urine. Also, we were in an apartment at the time and Bruno was peeing on newspaper. After his pee dried on the newspaper, we were actually able to see sparkles where the pee dried. Not very useful, I know.

Hope you get to the bottom of this.