Make the change gradually to avoid upsetting your dog’s stomach, Dr. Bartges says: “Transitioning over a week or so by slowly increasing the amount of raw diet while slowly decreasing the amount of the old diet is how I would approach it.”Dr. Bartges suggests a ratio of ¼ raw food to ¾ old diet for the first two days, then moving to half and half for two days, then ¾ raw and ¼ old diet for two days before moving to 100 percent raw food. “But it may need to go more slowly depending on how well tolerated” the food is by your dog, he says.As always, before switching to any new pet food, talk to your vet.