In some instances the first stage of labor is missed altogether.
Signs of labor to watch for are:
The first stage of labor can last 24 hours, and can go totally unnoticed. Do NOT give calcium during this stage of dilating. Calcium can only be given when contractions are a minute apart, and she is constantly pushing.
The second stage usually begins with a rather clear or mucous-like discharge from the vulva. In the second stage of labor contractions should start. There will be more discharge, and the presentation of a round, golf-ball size membrane sac of water. This sac is still the 2nd stage of labor and dilating. Do not give calcium. She is not ready to push. This is usually just the horn sac. Pup can follow in 20 minutes to a few hours. Some vets recommend not letting her puncture this sac. This is the protective sac that the puppies are in. But do not fret if she pops it. This is Her water breaking. After presentation of this sac, the puppy could be out in about 30 minutes, but it can take a couple of hours. If the dam continues to strain hard for longer than 45 minutes on a single puppy, it is wise to call your vet. (Remember there should never be time limits, as every situation is different.) It is always best to call your vet and do what he/she recommends.
If two of these sacs present themselves at the same time (especially if they are different colors), call your vet. This could mean that two puppies are trying to come out at the same time, another medical alert requiring professional help.
Dam in labor pushing out her puppies
Dam in labor pushing out her puppies
More info and pictures on first stage of labor.
Video clip of a dam in full labor, pushing
The normal body temperature for animals is generally higher than for humans.
The normal rectal temperature of a dog is 99.5° to 102.5°F. The normal temperature of a puppy at birth is 96-97°F. The temperature gradually increases with age until it is 100°F at 4 weeks of age.