Hi there my border x bitch was at that stage for around 24 hours,you just need to reasure her and keep an eye.When she gets to the stage of pushing,you cant miss it!,make sure that she doesnt strain for to long.The vet once told me any longer than an hour and seek veterinary advice.the time inbetween pups can be as long also,good luck,start stocking up on news papers.