Scaly leg mites are the most likely parasites to cause limping and lameness in growing and adult poultry. They are very common, spreading easily within a flock, and when introduced by new birds which are infested.
The mite burrows beneath the scales of the legs and feeds on the skin and tissue. The scales will appear lifted and roughened, and bad cases may bleed, look deformed, and be covered in crusty material.
To treat it, you need to kill the mite. Cover the legs in a thick barrier of grease, oil or petroleum jelly and apply it frequently (every 1-2 days) over 10-14 days. This suffocates the mites, and will also soften the damaged scales, which will eventually fall off and be replaced by new, shiny, smooth ones.
Light vegetable oil can be used but this needs to be applied more frequently than something with a thicker texture.
An old toothbrush is a good tool to thoroughly work a barrier into small gaps and around all the scales.
A general pest treatment like ivermectin applied at the same time can aid in eradicating the mites.
DO NOT use kerosene or diesel. This is an oldfashioned method which can burn the skin of the chicken, and both are toxic substances that can be absorbed into a bird’s system. Damage caused by scaly leg mite.
Knemidocoptes mite Image: Alan Walker, Wikimedia Commons