Until 3 days ago, my neighbor had 2 Buff Orpingtons. At 3pm on Sunday, she noticed that one of them wasn't moving and was having a little trouble breathing (opening her beak slightly with every breath). Earlier in the day, the same chicken was acting totally fine, just grazing in the yard doing her chicken thing. But by 10pm, the poor girl was dead. And now there's a sad Buff Orpington living across the street living all alone. My boyfriend and I will probably adopt her, but I'm not sure if we should quarantine or not. Are there any diseases that could cause a chicken to go from totally fine to dead in 7 hours? Our neighbor thinks she might have been poisoned by lawn chemicals (I guess they dumped a wheelbarrow full of chemicals down a ravine that the chickens sometimes visit). Another possibility is that she was attacked by a cat or something, but she showed no sign of physical injury. So, do I need to quarantine before adopting my neighbor's remaining Buff Orpington? It makes me so sad knowing there is a chicken across the street without any feathered friends, but I know my first responsibility is to keep my own flock safe. Thoughts?