Any reason I should be concerned???

[meadrian]

My 3 ten week old chickens are on day 6 of Corid. There is still some blood in the poo. Not bright red, but it's there. Should I be concerned? I thought it would clear up by now. I'm going to keep them on for 7 days, but is this normal to still have some blood? I'm starting to get worried!

Thanks!