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Scaly Leg Mites

Knemidocoptiasis

Scaly leg mites (Knemidocoptes spp) are a relatively common health concern for free range and backyard chickens worldwide. It is distinctly different than other types of mites. Scaly leg mites invade the unfeathered portions of the birds' bodies, specifically their legs and feet. Once there, they burrow underneath the scales and feed on the keratin. Over time, this causes the scales to become raised and thickened, sometimes protruding outwards.

Scaly leg nites are too tiny to be visible to the human eye. 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. 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 my 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

Flaking, crusting or roughened skin
Scaly, uneven, or raised scales

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.
Topical avermectin selamectin
Moxidectin

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