Did you read the link Rainbow left you?
If you do, you might understand some of the responses you are getting. Many, many people on this forum work in rescue and with the announcement of your upcoming "planned litter" that is a death sentence for some poor dog in rescue who will not get adopted :sad:
Your profile says that you love dogs...if you did you would understand that having "just one litter" is not a conscientious decision when so many are sitting in shelters hoping to be adopted before being destroyed.
I have no idea why your dog is attacking the other dog. Ask your vet next week when you bring your bitch in for her check up