A freind of mine brought his 6 month old bully amstaff mix over last week. We stepped inside and let her out in my dog yard with my 3 dogs. I heard some whining so I looked out and my chow shepherd mix was tied with her. I guess he didn't realize his bitch was in heat. My question is if he let the pregnancy go would having the pups hurt her? She is about 45 lbs maybe 18 inches tall and very stocky. My chow shepherd mix is about 26 inches tall and 65 to 70 lbs. He had plans of breeding her in the future so he's not happy about the idea of spaying her. I told him i heard of a shot that will stop the pregnancy but he's not happy about the possible side effects either. He wants to let it go I'm just concerned about the bitch having trouble delivering the pups due to the size difference and her age. Any advice would be appreciated thanks.