It sounds like poultry lice is a good thing to check for. You may or may not see the lice but you will probably see the egg sacs which are a grayish sort of oyster shell color at the base of the feather shaft.
Here is a link to another site that includes photos.
Scroll down to the last photo which gives a pretty typical lice infestation. The sacs could be smaller than those shown in the article.
http://forum.backyardpoultry.com/viewtopic.php?t=7961846
The lice will cause the chickens to lose their feathers or to pick at them and break them off.
It also sucks the nutrition from the chickens and can make them anemic or sickly.
If one chicken has lice, you will need to
check ALL of them that are sharing the coop/run and
ALL should be treated even if they don't have evidence.
What to do...
1.) Immediately, buy or order online
Permethrin 10%. The Permethrin 10% is less than $15 no more than $20. You get a 1 quart container of the liquid, which will last a while and it can be used on other animals for fleas, mites, etc. I ordered mine from:
www.firststatevetsupply.com
It is a pale yellow liquid and it works great.
It actually kills the eggs as well as the lice.
It's easy to use and the directions are on the label. Just mix it with warm water in a basin or small tub. Wearing a pair of rubber gloves, immerse the chicken up to the neck. They don't like it at first but they settle down and get quite calm, if you use warm water. While holding their body under the water
(never put their head under the water!!!) use your other hand to gently lift up the wings and feathers and tail. You want to get the liquid to soak through the feathers all the way to the down near the skin. Then gently, using a small sponge, dab at the feathers on their neck and between the wattles. Lice usually like the butt near the vent and under the wings. However, we got a 5 month old hen who had lice and she had them in the usual places but also up the back of her neck and between the wattles. A vet told me that those places were very common lice targets too.
2.) While you are waiting for that to arrive if you have to order it, try to get some Poultry Lice Dust or Seven 5% dust. The dust is inexpensive maybe $5. Open the shaker top and put a clean knee high stocking over the canister (I bought a cheap pair at the dollar tree for a buck) This will work sort of like a powder puff. You will need to 'powder' the chicken all over with the dust. Be careful around the face and try not to breathe the dust yourself.
The dust DOES NOT KILL THE EGGS, so you will have to
re-dust them again in 7 days, and then again in a week. It's sort of an on going maintenance thing from there on because the eggs hatch out.
I have had very good success with the Permethrin because it does kill the eggs, and i have not had any repeat infestations.
3.) You will need to boost your chickens nutrition because they will need to regrow those feathers. Chickens require a higher amount of protein when they are growing new feathers.
4.) Don't forget to treat the coop also it's easy to do with the poultry dust or seven 5%
Hope this helps
