Is there a home-made version of a urinary diet? Or maybe some herb I can use?

I have two 15 year olds, both of whom recently started eating organic grain-free raw diets after a lifetime of kibble. The only issue is Tigger cannot stop eating at least some Wysong Uretic without getting a UTI. Tabitha is kibble-free and looks and acts fantastic since kicking it to the curb-she actually became violently ill today after getting ahold of a few mouthfuls after not having it for a long time but was fine again after a nap and proper meal :) Tigger has shown some improvements but you can definitely tell Tabitha is bette-like zoom around the house and pounce my chest better. I really want that for Tigger too, so can I use an herb of some sort to replicate the diet? I was looking at D-Mannose... also, Wysong's pH - supplemnt looks like it might work...opinions? I'm perfectly willing to go to whatever trouble or expense necessary