While small amounts of plain yogurt or curd can be safe for some puppies, it's important to introduce it gradually and in moderation. Dogs have difficulty digesting lactose, so feeding them large amounts of dairy products like curd can cause an upset stomach and diarrhea. Additionally, some dogs may be lactose intolerant and should not consume dairy at all. It's best to consult with your veterinarian before giving your puppy any new foods to ensure that they are safe and appropriate for their individual needs.