
If she isnt straining yet i would give her more time, first stage labour can go on for a long time, one of my girls was panting for 26 hours, i was petrified things were not going well, my vet asked me to check to see if she was dilated myself and she was only slightly, then 1 hr later i checked again, she was fully dilated and then produced a very large litter with no problems.
Give her some more time and keep a very close eye, any signs of problems or any green/black discharge then take her in but she will probably get on with it in her own time. I know some say if a bitch has had a section then it is more likely to be a section again but i had a section with one of my girls and she delivered her next litter fine, so it is wait and see and just be vigilant.
Hope all goes well, let us know x