Sheep lice
Lice in sheep cause disease and production losses, leading to serious financial consequences to the farmer if they are not treated promptly. However, as irritation/pruritus is the main clinical sign in early cases of both louse and mite infestations1, it is critical to get an accurate diagnosis early, to know which targeted, effective treatment plan to implement.
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:
- Treat with a synthetic pyrethroid pour-on, such as Crovect™ Pour On, that kills biting lice
- Quarantine all incoming stock for 3 weeks
- Ensure fencing is sound to prevent straying on and off
- Disinfect livestock trailers after use
- Remove all debris (wool, etc.) from contaminated housing and do not re-stock for at least 3 weeks
Crovect™ Pour-On for sheep contains 1.25% (w/v) cypermethrin (cis:trans/80:20). For the treatment and control of headflies, tick infestation with a persistent efficacy of 10 weeks (the majority of ticks killed within 3 hours) and treatment of biting lice in sheep. Also for the prevention and treatment of blowfly strike in sheep. Legal category: POM-VPS.
Information regarding the side effects, precautions, warnings and contra-indications can be found in product packaging and leaflets; further information can also be found in the Summary of Product Characteristics. Advice should be sought from the prescriber prior to use. Use medicines responsibly
Crovect™, Elanco™ and the diagonal bar™ logo are trademarks of Elanco or its affiliates.
For product related technical queries, contact the Elanco Vets team:
Telephone: 01256 353131, selecting option 1 for technical services
Email: ElancoVets@elanco.com*
*please note this inbox will be checked during the next business day. If you require an urgent response to a product-use query, suspected adverse event or quality complaint regarding an Elanco product, please call 01256 353131 choosing option 1 for technical services. Outside of office hours, your call will be forwarded to our medical answer service and an Elanco representative will call you back. Thank you for your understanding.
