Wazine before Ivermectin a necessity?

[Jackie B.]

Shannon the Roo was humanely euthanized last night. He didn't even fight me when I did the deed. First chicken I culled. It sucked. Any suggestions for prevention in the rest of my flock? I'm out of town this weekend but plan to worm everyone on Monday. Had no idea that a flock could get mites in the winter. Living and learning the hard way isn't always so great.

(Shannon the roo is far right.)

Thanks especially to Dawg53 for the advice,
Jackie