Tonight we noticed that two of our Buff Orp chicks, about 3-4 weeks old, have a protruding line down the very middle of their backs. It looks like a swollen blood vessel but it's not pronounced. They're as active as ever but they consistently tip/bury water and food containers so they're thirsty often. I'll switch from wood shavings to newspaper tonight and see if that helps. Have you seen this before? Should I take a picture?