Dogs can eat purple potatoes and sweet potatoes, but they should be eaten in moderation. A little occasionally is okay. Eating too much may cause diarrhea in dogs. Sweet potatoes and purple potatoes are rich in nutrients, such as anthocyanins. Dogs eating some occasionally can help intestinal digestion and promote defecation. However, if the dog’s stomach is relatively fragile, it is recommended to feed less or not at all to avoid discomfort.