FORZA10 URINARY Active is a specialized diet that has been created by the FORZA10 R&D Center to help support a healthy urinary system by creating a urinary environment not favorable to the formation of struvite crystals. What's the difference between the Active ingredients in Renal and in Urinary formulas for cats? The pool of botanicals in Urinary Active and Renal Active are the same, since both address problems affecting the urinary tract, though in different ways. They are not 100% interchangeable as Renal Active is specific for cats with kidney problems (mainly chronic kidney failure), so it has a lower protein level and a higher energetic content. Urinary Active, on the other hand, is specific for cats with FLUTD (feline lower urinary tract disease) and/or a tendency to develop struvite stones, so the kibbles are formulated to be able to acidify urine, way more than the Renal kibble. The main difference, then, lies in the kibble formulation: the botanicals all help kidneys work better and help keeping the environment of the urinary tract in optimal conditions (important things for both kidneys and the lower urinary tract), while kibbles are either lighter on the kidneys or more acidifying on urine. Renal Active has a slight acidifying effect as well, so in some cases it can be used instead of Urinary, but it has to be evaluated case by case.