Lice infestations in Cattle and Sheep: Indoor Winter Housing

What are lice?

Lice are ectoparasites that live permanently on their host. They either feed off blood meals or on the skin, hair, fleece or any other debris on the skin.  These are named sucking or chewing lice, respectively. Bovicola ovis and Bovicola bovis are chewing lice which are found on sheep and cattle, respectively. In the UK, three species of sucking lice commonly affect cattle — Linognathus vituli, Solenopotes capillatus, Haematopinus eurysternus — but they are not a problem for sheep.

Lice in sheep and cattle tend to be more prevalent in the winter months. This is often because animals are housed indoors and have thick winter coats. Lice are passed on by close contact between animals at times such as feeding or handling. The severity of the infestation can also depend on breed, fleece length and health status of the animal.

Temperature can play are part as lice do not like warm, humid weather. As such, they do especially well in colder temperatures. Combined with close animal contact, this adds up to prevalent lice in winter.

How do I know if my animals have lice?

Generally, a low infestation of lice will not have any obvious bad effects and commonly goes unnoticed. However, when lice have good conditions to multiply, they can become a problem. Typically, heavy infestations are indicative of welfare problems within a flock. Heavy infestations may cause severe itching causing animals to rub themselves on fences and posts, developing bald patches. In severe cases, suckling lice may cause anaemia in cattle and can even aid in the spread of ringworm and tick-borne fever.

When diagnosing lice in sheep, be careful to not confuse lice with mites which cause sheep scab, as the signs can seem similar. Sheep with mites also present bald patches and itching. Sheep can also have both mites and lice simultaneously so just because you have identified one do not discount the alternative. Lice and their eggs can be seen by eye and/or by using a magnifying glass and are typically between 1-5mm in length. If you are unsure you can always call your vet or send a sample to us at RRL and we will identify the parasite for you.

My animals have lice, what should I do?

Luckily there are pharmaceuticals available to treat lice, however some products may be more suitable than others. For instance, pour-on products will not be suitable for sheep with large fleeces. In this instance, it may be worth shearing the sheep prior to treatment. Using pour-ons with a heavy fleece can lead to resistance problems as the full dosage of treatment may not get to all of the lice. There are also injectable treatments however these are not very effective against chewing lice. Plunge dipping to treat other parasites such as sheep scab can also be an effective treatment for lice.

Pour-on and spot-on products are suitable in cattle, as well as injectables. Similarly to sheep, the use of endectocide treatment for other parasites such as roundworm or ostertagiosis can also give some protection from lice.

To prevent  future infestations, ensure animals are in good health, are well fed, housing has low stocking density with good air flow, as well as considering shearing if you know there are some infested sheep within your flock.

Does it matter that my animals have lice?

Cattle can experience up to 10% loss in production when heavily infested with lice. On top of that, lice cause significant welfare concerns. Constant rubbing and scratching of the affected areas can lead to lesions and rough skin, which can depreciate the value of cattle. In sheep an immune response to lice can produce a skin defect named ‘cockle’. This can also lead to depreciation of the leather quality and value. Furthermore, due to the irritation of the skin cattle and sheep may spend reduced time feeding and more time rubbing, leading to reduced feed intake and decreased weight gain.

You can find further information here:


NADIS – sheep and cattle