Sheep lice

Lice are small, pale red/brown flat insects (approx. 3-4mm long) feeding on skin debris and hair, living within the centimetre of the wool closest to the skin.

The most common louse in sheep is the biting or chewing louse Bovicola ovis. Lice can be found anywhere on the sheep and do not produce a definite scab lesion. Lice populations are influenced by body condition – the lower the body condition score the higher the population of lice.

Lice can cause intense irritation, restlessness and scratching as infested sheep rub themselves. The fleece appears rough and pulled, with numerous loose strands of wool. Sheep can bite and nibble at the fleece.

The main method of transfer is animal to animal contact. Lice are, therefore, a particular problem in housed sheep, although it is not a building problem. 

As lice can live off the animal for 16-17 days, it is possible for a farmer to bring an infestation onto their farm through brought in stock, clothing or livestock transport.

As sheep will rub and scratch if they are infected with either lice or scab - or even both at the same time - an accurate diagnosis by a vet will be needed to determine the correct treatment. A blood sample or a skin scraping examined under a microscope will confirm if the issue is caused by mange mites or lice.

Lice are primarily an autumn and winter parasite as they do not like the dry bright conditions seen in summer.

Once an accurate diagnosis has been confirmed, best practice is to: