Does changing your dog"s food cause diarrhea that is normal?

Yes, it has always given my dogs diarrhea if I’ve switched the food too fast. You might want to scale back on the new food, and increase the transitioning period over another week. I’d go back to feeding her half Science Diet and half new food for 3 days, then go to 3/4 new food, 1/4 Science Diet for another 3 days. You might want to add 1-3 tablespoons of plain, unflavored yogurt to her food at each feeding. Yogurt soothes dogs’ upset tummies. Make sure you’re mixing the two foods together during the transition, and not feeding all the new food at one feeding, and Science Diet at the other feeding.

The diarrhea doesn’t usually last very long after the transition, but it can be pretty nasty while she’s getting used to the new food.