Yes, a dog CAN eat too much raw rice. The rice will continue to expand and draw moisture within the dog's digestive tract. Your dog has consumed almost 1/20th of her weight in raw rice. Rice doubles in volume in general. Call you vet immediately. Some remedies include intentionally causing the dog to vomit the rice if within a short period of ingestion. This can be done by administering a small amount (less than 1/4 cup in your case) of hydrogen peroxide, and this is not an easy task. The best idea at this point is to consult your vet to ask for advice after describing the amount of time that has passed, the amount ingested, your dog's weight and his/her general health condition. Meanwhile, keep your dog hydrated. He or she will almost surely become increasingly uncomfortable and will need fluids constantly until he can be seen by the doctor, or you can take alternative measures to induce vomiting, as your veterinarian recommends by phone consult.