If you're using it to encourage appetite, you only need to sprinkle on enough to get the cat eating.
If for diarrhea, putting some in every meal provides some of the good bacteria for every meal.
Thanks BJ. I should have specified. I think I switched the food too quickly and at least Shiloh has diarrhea. After I posted the second post, Shiloh went in and ate half of Spuds' food. He still won't touch it.
It took me almost a whole month to switch Goof over, I had no problems. Did you put the Fortiflora in Spuds food too? It won't hurt him if you do, and so then Shilo will be getting it anyway.
Maybe try putting a very small amount in Spuds food to start, then increase a tiny bit each day? Jeez, the psychology we need to use just to take care of our kitties! Lol