I don't know about using S.D. cat food but a friend feeds Science Diet Kitten Food. I'm taking care of them while she is gone for a while. The poop is soft, sometimes puddly, (six ferrets), one has rather liquid poop. Otherwise they seem healthy; I wouldn't use it for my own. They are quite happy on TF. Someone else I know uses a 50/50 mix of Purina One Kitten Food and WalMart's Maxximum Nutrition Kitten Food and they do quite well on it. They also have a bowl of TF to snack on but mostly they eat the mix. Poop is a little softer but not as bad as the others on the Science Diet. Carol O., Tucson [Posted in FML issue 4596]