What drops in dog before whelping?

Before whelping, a dog's body undergoes several changes, including a drop in body temperature. Typically, a dog's temperature will decrease to around 98°F (37°C) or lower, about 24 hours before labor begins. Additionally, the dog's appetite may decrease, and she may exhibit nesting behavior as she prepares for the arrival of her puppies. These signs indicate that whelping is imminent.