Lice

There are two main types of lice that affect livestock: biting lice and sucking lice.

Biting lice

Biting lice feed mainly on skin scurf, superficial skin cells and bacteria.

Sucking lice

Sucking lice feed by penetrating the skin with their mouth parts and sucking blood from capillaries and blood serum that exudes from the damaged skin surface.

Cattle and goats can be infested with either chewing or sucking lice; sheep are mainly infested with chewing lice. Lice are usually host-specific, which means that different species of lice are found on cattle, sheep and goats.

Conditions where infestations are likely to occur

  • Winter through to early spring.
  • Longer fleece/hair in winter tend to develop the heaviest infestations.
  • Animals in poor condition.

Identifying and diagnosing infestations

Lice are usually suspected in animals that are rubbing, scratching or biting at themselves. In heavy infestations, scaly skin and raw areas may be present. Hair or wool loss can occur. In sheep, fleece derangement may also be present.

Lice can usually be seen on cattle, sheep and goats by parting the hair or fleece. Lice can then be seen moving away from the light.

A lice detection test is available that detects lice on sheep by testing the wool grease in shearing cutters.

Strategies to prevent infestations

  • On properties where lice are not present, source animals from other lice-free flocks or herds. Thoroughly inspect animals before purchase and assess relative risk based on trading activities and management.
  • Always request an animal health statement when purchasing stock so you are aware of the disease status level of assurance that is being provided by the stock vendor.
  • Maintain secure boundary fences to prevent stray stock entering the property.
  • Consider treating new mobs of sheep after shearing to eradicate lice before exposing existing flocks to new sheep, unless sure they do not have lice.
  • Put lousy animals and introduced sheep through the yards last.
  • Shearers need to microwave their moccasins before shearing to kill any lice that may have contaminated them from the previous flock.
  • After handling lousy animals, change clothing before handling animals that do not have lice.
  • Maintain cattle in adequate condition during poor seasons to prevent outbreaks of lice.
  • In intensively managed animals, there is a chance of re-infestation from contaminated facilities if animals are treated with a non-residual chemical and returned directly to the contaminated facilities. Although the chance of this is low, a 2-3 week exclusion period is usually a good idea.


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