Lice and Mites


There are two types of lice found in the UK horse population. The most commonly encountered is Damalinia; a chewing louse of about 5mm in size – they can be seen with the naked eye. There is also the much smaller (2 mm) and more rare Haematopinus which is a yellow coloured louse that sucks blood from the host. The whole life cycle of the louse takes place on the host; adults lay eggs from which larvae hatch that develop into adult lice, all within about 14 days! Both are usually found in the dense hair especially around the mane and tail. Particularly native breed horses with thick winter coats seem to be preferred by lice. Horses are often intensely itchy (puritic), restless, rubbing and sometimes have flaky skin as a result. Any horse can be affected but is is more common in the very young, old or immune suppressed (Cushings disease!). If your horse is itchy during the winter months check for lice!


Deosect (Cypermethrin) is an effective treatment against lice. It kills adult lice only, therefore treatment should be repeated after 14 days.

How to use Deosect:

  • For very small (Shetland) ponies add 4 ml. of Deosect to 400 ml. water.

  • For mid sized ponies add 8 ml. of Deosect to 400 ml. water.

  • For horses add 10 ml. of Deosect to 500 ml water.

  • This can be applied by being hand sprayed or sponged onto the coat.

  • Once diluted it must be applied within 24 hours.

  • Care must be taken when applying the mixture – gloves, face mask and protective boots. Avoid inhaling the mist. Care as the liquid is flammable.

  • Treated animals cannot enter the food chain and Section IX must be signed in the passport.

If you have a persistent case or if you have any questions, please contact the practice.

Feather mites

Also known as ‘heel mange’ – this disease is caused by Chorioptes mites. It can be a very distressing condition, making horses extremely itchy. Affected horses constantly stamp and bite the legs or rub the backs of the fetlocks and pasterns against anything they have access to, often the stable wall or fence posts. It is most common in heavily feathered breeds, particularly coloured cobs, draught horses and Friesians.

Chorioptic mites are far smaller than lice and not visible with the naked eye. They live on the horse’s hair and skin and even burrow into the skin causing irritation. They can easily be seen on microscopic examination of skin scrapes of affected animals but usually the presentation is that typical that treatment will be started following clinical examination only. When a horse is affected not only adult mites will be present but also eggs and developing larvae. It takes approximately 2 weeks for eggs to develop into adults. As eggs cannot effectively be killed with medication, any treatment should be repeated after +/- 2 weeks.

There is currently no licensed veterinary product to treat Chorioptic mange in horses so vets at Pool House Equine Clinic use a cattle product called Dectomax (doramectin) by sub-cutaneous injection. Dectomax has proved safe and very effective in reducing the number of mites and reaches the whole body – that way even the few mites higher up on the body can be killed. However, mites can live in the hair and even in the environment of the horse for short periods of time where they are inaccessible to injectable medication. To reduce the numbers of mites present it is therefore advisable to closely clip the feathers if injections only are administered. More recently we have started using a topical wash with Panomec (ivermectin, closely related to doramectin) which has to be dissolved into water and sponged onto the legs up to the elbows and stifles. This is more effective in killing mites in horses where owners are reluctant to remove the feathers. Occasionally Frontline spray for dogs has been used but we have found this to be slightly less effective than either of the previous treatments and it is more difficult to apply.

Depending on your horse and circumstances a suitable treatment plan will be designed. Because these mites can survive in the environment it should not be forgotten to clean and disinfect the stable as part of the treatment plan. The more meticulous this problem is handled, the longer horses will stay problem-free. It is almost impossible to completely eradicate the infestation however and it will therefore in most cases recur on the long term necessitating repeated treatments.

Example of a good treatment plan;

– Start treatment with an injection of Dectomax by your vet.
– Followed +/- 2 weeks later by washing the legs with our mite-solution;
– dissolve contents of a 250 ml bottle of solution into 10 l warm water.
– sponge onto legs up to elbows and stifles.
– leave to dry, do not rinse off!
– Empty stable of all bedding and steam clean after each treatment.



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