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We see a lot of itchy horses during the spring and in many cases lice are to blame.  Lice are particularly common during the winter when turned out horses stand closer together, especially if they have thick winter coats where lice can thrive. Infested horses are often seen rubbing and biting at themselves and the coat can have a moth eaten appearance with a rather nasty 'dandruff' look about them.  Moderate or severe infestations can even cause weight loss and amaemia.

There are two types of lice that infest horses: chewing lice that feed on skin debris and biting lice that feed on blood and tissue fluid.  Lice are 1-2mm in length and can be seen with the naked eye during careful examination (if you have good eyesight!). The eggs or 'nits' are also visible, tightly adhered to hairs as tiny white blobs, whilst the adults tend to lurk under the mane.

Lice are mainly spread by direct contact from one horse to another, but can spread indirectly by shared rugs and grooming equipment.


There are a variety of treatment options available but we find the pour on products are usually more effective than the proprietary powders that can be purchased over the counter.  We recommend Deosect washes for both types of lice.  It is important that treatments are repeated every 10 to 14 days for at least 2 treatments to clear infestations.

Whilst Deosect is effective against killing adult lice nothing will kill the eggs which is why nit combs are used for head lice in children.  Eggs normally take 10 days to hatch out so by repeating treatment every 10-14 days any newly emerged adults will be killed before they have the chance to reproduce.

Bathing with a selenium-based shampoo can also help with scaly skin and 'dandruff' which is often associated with a lice infestation.

Ideally, in contact horses should be treated simultaneously to prevent reinfestation.  Clipping affected horses can also be useful to destroy the louse's preferred habitat and to remove eggs. For persistent cases, it may also be worthwhile treating the environment - rugs can be steamed or washed at a temperature above 50 degrees celcius and grooming equipment can be emersed in Deosect solution.

If you think that your horse may have lice and would like further advice, please contact BELL on 01622 813700 and speak to one of the vets

For further information, please see the horse owners booklet on Parasite Control in the 'Health Horses' series by MSD Animal Health.