mites and lice what to use and where to get it...and can you use as a preventative?

[Fortune]

I'm having a dilemma with my girls. I have 5 hens all the same age of various breeds and all but one quit laying after they started laying again in late Jan. I first thought it was rats, but killed most of them, but still nothing. Now I'm wondering if it could be mites or lice but I can't find any. I do see black dots around cloaca area but just one or two and look more like freckle than a bug. My small Welsummer is losing feathers like she's molting again. Can I treat them for mites and lice with Ivermectin and what type do I buy? I saw one video about Ivermectin drops that are actually for cattle but work for chickens in tiny amounts applied topically to the skin. Any help would be great. Three of them are very broody at the same time so I'm overwhelmed and worried for them. Thanks in advance.
I have two welsummers, one buff orpington, and two blue jersey giants. All are 14 months old and have been very healthy and happy till this. The Buff is the only one who's unaffected by any of it.

I just watched two videos on treating and preventing and both disagreed with each other. I don't want poisons due to living on a canal with lots of wildlife. Does anyone see anything in this picture that tells you something? She's losing a lot of feathers but already molted in Jan.

 

[oldhenlikesdogs]

Is it warming up where you live? If you saw a surge in laying in January than more than likely it's getting warmer and some will slow down or even stop laying as temperatures increase for summer. You generally see the best production in early spring and laying tends to drop off as the year progresses in most breeds. Being broody will affect laying.

Most chickens have a small degree of mites which can be managed by the birds by taking dust baths. You can help out by treating the coop a few times a year, and birds if needed. I prefer a pyrethin based poultry dust.

Ivermectin isn't labeled for use in chickens. I know people use it but I would be concerned about any withdrawal period.

Your picture looks like new feathers coming in. I don't see anything that looks like parasites. The feathers on your hens are getting older and will continue to look more worn as the season goes on. They should molts in the fall and get all new feathers. In the meantime lost feathers get replaced as long as they have fallen out and aren't broken off.