I have two mature cats (10+ yrs) and I decided to try something different for them. One of my boys has been having digestive problems ever since he ate it and the other started loosing his hair in clumps. It looked like someone had taken scissors and cut his hair. They are both medium hair, orange tabbies and they have never had these type of health issues until I tried them with the Purina One. Personally I think this stuff is or could potentially be deadly for cats and I would not recommend it to anyone. Even though I have stopped feeding my two boys this severe concoction that the manufacturers call food, they are slowly returning to their normal selves.