Poultry Production in Mississippi
The producer will often observe shanks or legs of birds that have scales that seem to protrude straight out from the leg. This problem is caused by small scaly-leg mites that bury under each scale and cause an irritation of the skin and the production of cells and substances that try to "wall-off" these mite parasites. Most free roaming chickens will have infestations of these mites but they seldom cause problems other than creating an irritation to the birds.
Effective treatments of the condition include weekly coating of the birds' legs with petroleum-based or mineral oils that suffocate and kill the mites. Alternative treatments include the use of approved pesticides like permethrin. All birds in the flock should be treated to reduce reinfestation from untreated birds.
A more detailed discussion of the scaly-leg mite is included in Diseases of Poultry.