Lice in sheep and cattle – what are lice?

Lice are endoparasites that live permanently on their host, that either feed off of blood meals or on the skin, hair, fleece and any other debris on the skin.  These are named sucking or chewing lice, respectively. Chewing lice found commonly are Bovicola ovis (sheep) and Bovicola bovis (cattle). Sucking lice are also found to affect cattle with 3 species commonly affecting the UK; Linognathus vituli, Solenopotes capillatus, Haematopinus eurysternus, whereas sucking lice are not a problem in sheep in the UK.

Lice in sheep and cattle tend to be more prevalent in the winter months due to animals being housed indoors and thick winter coats. Lice are transmitted by close contact between animals at times such as feeding or handling. The severity of the infestation can depend on breed, fleece length and health status of the animal too. Temperature also plays are part as lice do not like warm, humid weather and so do especially well with colder temperatures combined with close animal contact for increased transmission and replication.

How do I know if my animals have lice?

Generally, a low infestation of lice will have negligible clinical effects and commonly goes unnoticed. However in favourable conditions such as indoor housing and thick coats or fleeces, combined with poor management or underlying nutrition and health problems, lice 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, be careful to not confuse in sheep with mites causing 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, so 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, not to mention the affects upon their welfare. 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’ which may 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.

Some useful references for further information can be found below:

https://www.scops.org.uk/external-parasites/lice

https://clients.nadis.org.uk/planner-articles/lice-in-sheep

https://clients.nadis.org.uk/planner-articles/lice-in-cattle

https://nadis.org.uk/disease-a-z/cattle/ectoparasites-of-cattle

https://www.msdvetmanual.com/integumentary-system/lice/lice-in-cattle#v15740374