I decided to keep two hens and one rooster as a breeding pair for future birds to slaughter a few years ago. Everything went fine till about lets say at week 16-20, the rooster got down in his legs and couldn't walk so I separated him and tried to get him back to health, after about two weeks of attempting to get him back to health he died of probably a heart attack. About one to two months later one of the hens showed signs of being ill, I tried to help her through it but about two-three months later she died on me to. The final hen lived to be just a little over two year old when one of my other roosters while trying to mate with her hurt her side, I separated her and keep trying to get her back to health for about a month, but finally one day when I had her out in the yard feeding her by hand and giving her water she died in my arms. That hen gave us all very good memories of having her around because she was so different than the other chickens and we all loved her very much. With that being said I will never raise Cornish cross past about 10 weeks old again no matter the circumstances, they just get too big and eventually die of a heart attack. They grow too fast for their internal organs to develop with their bodies and this is what gets them. I hope you decide not to try to keep them as pets, but if you do the short time you get to spend with them will be unforgettable, if you can get past the part of losing them.