You have not mentioned breed of your dog. Dogs can be used for the breeding again four months after the delivery of puppies or in the next heat cycle after delivery of the puppies. Pregnancy in dogs does not affect their next heat cycle which occurs on the schedule time that is 6 months after the last heat period. So, you should wait for next heat cycle which can be occur after 4 months of delivery.
I have a bichon frise how long after birth do I wait to breed her again
Please do not use her as a breeding machine. Thank you.