Scaly leg mites (Knemidocoptes mutans
) are a relatively common ectoparasite of chickens, affecting backyard and free range flocks worldwide. K. mutans
are sarcoptic mites (burrowing mites) which burrow into the cornified epidermis of the skin, causing tissue damage. The mites are most often found on the legs and feet, but occasionally the comb, wattle, neck and/or beak. The presence of the mites causes irritation and hyperkeratotic lesions.
Prolonged infestations with K. mutans
can lead to necrosis of the toes, lameness, and permanent deformation of the feet. In addition, the compromised skin barrier puts the birds at higher risk of developing secondary bacterial infections.
Clinical Signs of Scaly Leg Mites in Chickens
The scales on the chicken's legs and feet should normally appear smooth and flat. When infested with K. mutans
the scales often appear dry, crusty, uneven and raised. The skin will be thickened.
Eventually, the heavy crusting of the scales can start to interfere with joint flexion, resulting in lameness, deformity, and necrosis.
Transmission of Scaly Leg Mites
are spread between chickens by direct contact with infected birds. They are initially introduced into a flock through adding a new chicken who is infected already, or exposure to wild birds or rodents.
Treatment of Scaly Leg Mites in Chickens
In order to initially suffocate the mites and help promote growth of new scales, paraffin oil or petroleum jelly (Vaseline) is applied to the legs and feet of each infected bird. Repeated daily until the old, damaged scales have fallen off, and new healthy scales have grown in. In moderate to severe cases, administration of 1% Ivermectin or Moxidectin is needed.