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Scaly Leg Mites

Knemidocoptiasis

Scaly leg mites (Knemidocoptes spp) are a relatively common burrowing mite found on the legs and feet of free range and backyard chickens worldwide. These mites burrow underneath the scales of the bird's feet and legs and feeds on the keratin. Over time, this causes the bird's scales to become raised and thickened, sometimes protruding outwards.

What are scaly mites?


K. mutans is the most frequently reported species found on chickens, and on occasion, K. gallinae and K. pilae. They are microscopic round mites with stumpy legs, claw like structures and tactile hairs. They are so small in fact, that you need a microscope to actually see them. It takes them 10-14 days to complete their life cycle, in which they spend their entire time on their host (the bird).

How do I know if chickens have scaly leg mites?


Healthy chickens have scales that appear smooth and lie flat against the surface. When chickens are infected with scaly leg mites, the condition of their legs and feet will start to slowly deteriorate. Early signs include flaking, crusting, peeling, roughening or uneven-looking scales, with some lifting upwards. One or more flock members might be infected, since the mites will move from bird to bird. Eventually, the heavy crusting of the scales can start to interfere with joint flexion, resulting in lameness and deformity. Infections with scaly leg mites can also be complicated by secondary bacterial infections and gross tissue inflammation.

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?


Treatment of scaly leg mites in chickens consists of topical oil-based products or sprays and an orally administered dose of Ivermectin to each bird. 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.

Clinical Signs

Scaly, raised encrusted scales on the legs and feet
Lameness

Diagnosis

  • History
  • Clinical signs
  • Physical exam
  • Skin culture

Treatment

NameSummary
Paraffin oilApply over the bird's feet and legs.
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.

Support

Prevention

  • Provide flock with a dust bathing area
  • Maintain a clean environment

Prognosis

Depends on how quick the birds are treated.

Scientific References

Good Overviews

Blogs

Risk Factors

  • feather-legged chicken breeds are more susceptible to invasion by scaly leg mites.
  • Recent relocation to a new environment

Case Stories