The scaly leg mite (Knemidocoptes mutans) is a tiny pale gray round creature, only about 1/100-inch in diameter. Despite its small size, in large numbers it can cause big problems by digging under the scales of a chicken leg and deforming the shank, feet, and toes. Unfortunately, dealing with scaly leg mites is a common problem for many backyard chicken keepers.
Scaly Leg Mites
Scaly leg mites burrow under the scales on a chicken’s shanks and feet, raising the scales by generating debris that accumulates beneath the scales. As a result, the chicken’s once-smooth shanks thicken and crust over, and eventually become deformed, causing the chicken to go lame.
Scaly leg develops gradually and is more likely to be obvious in older chickens, but it also affects young chickens kept with old chickens. Besides spreading from infected chickens, these mites may be brought in by wild birds.
When one chicken is infected with scaly leg, the mites slowly spread to other chickens by traveling along the roost. Their spread may be controlled by brushing perches once a month with a mixture of one part kerosene to two parts linseed oil.
Treating Scaly Leg
Once scaly leg mites settle in, they burrow deeply under the leg scales and spend their entire lives on the chicken, so you’ll have a hard time getting rid of them. A common treatment involves physically smothering the mites by dipping affected legs in vegetable oil, coconut oil, or linseed oil.
In a pot or can 5 to 6 inches deep, place about 4 inches of oil. Dip each affected leg until it is well coated with oil up to the feathers. Repeat every 3 days for a mild infection, daily for a severe case.
Continue until the old scales pop off and the shanks appear normal, indicating the legs are completely free of mites. But don’t expect severely damaged scales to return to normal.
Less messy than using drippy oil is liberally coating the shanks and feet with petroleum jelly (Vaseline). It stays on longer than oil, and therefore needs to be repeated only about once a week.
The Ivermectin Solution
Some chicken keepers — especially those with feather legged breeds like Cochins or Silkies — prefer the even less messy method of using liquid ivermectin. This naturally occurring compound with potent insecticidal and anthelmintic properties is used as a systemic livestock and human dewormer. It is effective against a wide range of internal and external parasites.
However, the overuse of ivermectin can result in resistant parasites, eventually reducing its effectiveness, and an excessive dose is toxic to chickens. Ivermectin is not approved for chickens kept for meat or eggs, since no formulations are sold specifically for poultry and therefore no withdrawal period has been officially published. Unofficially, the withdrawal time is 21 days.
To treat scaly leg mite, give the chicken 0.1 mg ivermectin per pound of body weight. Either place the ivermectin either in the chicken’s mouth or on the skin under the feathers at the back of the neck. Treat the chicken again in two weeks, at which time the raised scales should start to pop off. After two more weeks, treat the chicken a third time. By then you should see fresh scales growing on its legs and feet.
Preventing Scaly Leg
The best way to avoid scaly leg mites in the first place is to avoid bringing chickens into an existing flock from outside sources. Barring that, isolate new chickens and treat them as if they have scaly leg mite, whether or not you can see visible evidence. It’s much better to err on the side of safety than end up dealing with scale leg mites in your entire flock of chickens.
And that’s today’s news from the Cackle Coop.
Gail Damerow, author, The Chicken Health Handbook, source of the above illustration.