The only problem I've ever had was all our guinea hens got sold or kiled by predators...except for one. She and the horse became good friends and spent all their time together (she'd sleep on his back and everything). She became the last guinea around late summer...that next spring she started laying eggs in the barn. We didnt know much about birds at the time and just kinda let her do her thing. Turns out she didnt have enough calcium in her diet and ended up pushing her insides out. The vet said they might have been able to put everything back in and she might have been okay but she stepped on her intestines before we could get to her and punctured them with her talon. She had to be put down 
