When a dog is ready to have puppies, it will not be interested in eating for 24 hours before, it will lick its vulva and it will have tighter contractions in its stomach that may or may not be noticeable to the owner. Some people will say that checking a dog's temperature can help, but only some dogs will lower their body temperature by a degree or two before giving birth to puppies.
The most obvious sign for the owner is the appearance of the "water sac." This means that the puppies are on the way and in the pelvic area. In many cases, the dog will have trouble giving birth to the first puppy. The owner may see moaning and intense pushing. This does not mean trouble unless it goes on for an hour. If this has been going on for an hour or more, then the dog should be taken in to the veterinarian or emergency veterinary hospital.
The owner should set up a specific place for the dog to give birth. The owner should let the dog sleep there during the night and explore the area during the day so that it is familiar with it. The area should be clean and soft, so only use blankets or carpeted areas that can get blood on them. It should also not be loud or have distractions from young children or other pets.