Dogs Temp When Going Into Labor?

Average gestation is 59 to 63 days from the first tie (calculator in first link below) though can be a little earlier around 57 or up to 68 (time to be concerned and are more likely to need assistance or c-section at that length and more so on smaller breeds). During the pregnancy some of the standard prenatal care consists of things like ultrasound/x-rays for many reasons having to do with the health of dam and pups, confirmation (by ultrasound or blood test earlier so call your vet if your pup is or may be pregnant and you haven't done that yet) and knowing whether difficulty is very likely based on the visuals if not a general c-section breed. You will also likely get a good idea of how many if not exact and this is exciting but also gives you a better idea of when she's done or if there is a pup left to decay and cause infection and even helps evaluate distress when she has stopped or seems to tired to continue or there is too long a period in between pups and you know there are more during a free whelp.
During early labor the females temperature will drop to around 98. It is important to know when this occurs since if there are no pups within 24 hours of the temperature drop (active labor) there is likely a problem and the vet should be called (or if c-section breed that it is time to head in). If the pups are free whelped (non c-section) the dam is examined 24 hours after to be sure there are no complications (rupture, torsion, prolapse hemorrhage ect.) and retained placenta's or pups to cause deadly infection. She may need or benefit from an injection to help clean her out faster at that time (also to try and prevent infection). The veterinarian will usually go over the next steps and more common danger signs and problems (like mastitis and eclampsia) for the nursing stage at that time.
www.askabreeder.com  
http://drnelsonsveterinaryblog.com/2009/01/01/canine-labor--when-to-call-the-vet.aspx  
www.learntobreed.com  
www.dogbreedinfo.com  
www.marvistavet.com
www.lowchensaustralia.com www.wildheirlabradorrescue.org  
www.dogfoodanalysis.com