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Scaly Leg Mites

Other Names: Knemidocoptiasis, Cutaneous Knemidokoptosis

Scaly leg mites (Knemidocoptes mutans) are a relatively common ectoparasite found in adult backyard chickens, turkeys, and pheasants. They are extremely tiny (not visible to the naked eye) round mites with stumpy legs, claw like structures and tactile hairs. Scaly leg mites burrow into the skin on the birds’ legs and feet where they will spend their entire life cycle (10-14 days) digging tunnels, eating their skin, laying eggs, and leaving droppings behind. One or more flock members might be infected, since the mites will move from bird to bird.

How do I know if my chickens have scaly leg mites?


Healthy chickens have scales that are smooth and flat. Early signs of invasion with scaly leg mites are the appearance of flaking, scaly, crusting, and/or thickening of the skin on their legs and top of their feet. The scales will roughen, become raised, and some may protrude upwards. Eventually, the heavy crusting of the scales can start to interfere with joint flexion, resulting in lameness, deformity, and necrosis.

In addition, chickens infested with scaly leg mites are at risk of developing secondary bacterial infections and fungal pyoderma.

How do chickens get infected with scaly leg mites?


Scaly leg mites are spread between birds by direct contact with infected flock members. They are initially introduced into the flock through wild birds, rodents, or by already being present within the soil and surrounding environment.

How are scaly leg mites treated?


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. Concurrent treatment with ivermectin is also beneficial.

Clinical Signs

Flaking, crusting, scaling, or roughened skin
Uneven or lifting of scales

Diagnosis

  • History
  • Clinical signs
  • Physical exam
  • Skin culture

Treatment

NameSummary
Paraffin oil or Petroleum jelly (Vaseline)Apply over the bird's feet and legs.
IvermectinGiven orally or topically in 3 doses at 0.2 mg/kg of body weight, once every two weeks. Two weeks after the first treatment, the scales should be sloughing off, and by the third treatment, new scales should have grown in.
DO NOTEver cut or pick off scales as this can cause damage to their legs and feet.
Topical avermectin selamectin
MoxidectinPour-on or injectable forms are both effective, and available in 0.5% and 1% preparations.

Support

Prevention

  • Provide flock with a dust bathing area
  • Maintain a clean environment
  • Keep rodents out of coops
  • Prevent contact with wild birds
  • Thoroughly clean and disinfect any tree branches brought in to be used as perches for birds.

Prognosis

Depends on how quick the birds are treated.

Scientific References

Good Overviews

Blogs

Risk Factors

  • Feather-legged chicken breeds are more susceptible.
  • Recent relocation to a new environment.
  • High populations of wild birds

Case Stories