Following mating dogs can remain "tied" together for an hour. Sometimes the male dog turns around and the dogs appear end to end. This is normal and you should not try to separate dogs that are tied-up. This may well have resulted in a fertile mating. There are particular signs of pregnancy you may notice but the only way to conclusively determine if your female is pregnant is to get a blood test or ultrasound from your vet.
My Chihuahuas Got Stuck Together For The First Time... Do Dogs Get Pregnant The First Try And If So Should I Separate Them Now?
While they are stuck together DO NOT separate them I tried to do that the first time my dogs got stuck because I didn't know that was natural but it can cause complications and can become serious and yes they can get pregnant on the first try it happened to my dog and she gave birth to 7 gorges cattle pups.
Leave them together until you know that she is pregnant and when she is almost giving them birth separate them the dad may come aggressive agents mom and babies.