If a male dog is heartworm pos he get female with pregnant will the puppies be pos?

Not necessarily. Puppies cannot be born with heartworms. The larvae of the heartworm must first develop inside a mosquito, and then be transmitted to the puppy through a bite from the mosquito. So, even if the male dog is heartworm positive and the female dog becomes pregnant, the puppies will not be born with heartworms. However, they will be at risk of developing heartworms if they are exposed to mosquito bites.