Horse Disease Focus - Lice
Horses and External Parasites
One piece of good news is that horses do not get fleas. However, they do get lice. (Horses do not get fleas because fleas lay eggs in an animal's bedding, not on the animal itself. Equines move around too much for fleas to be able to do this).
Horses, donkeys and mules are affected by two species of lice, Haematopinus asini and Damalinia equi.
The common symptom of a lice infestation is scratching or rubbing. Rubbing of the mane and tail alone may be a sign of H asini infestation (it is also a classic symptom of sweet itch, but lice and nits can generally be found with visual inspection). D equi is generally found on the sides of the neck, flanks and base of the tail.
Other symptoms of lice infestation include a loss of luster or shine in the coat, hair loss affecting the mane, tail, neck and/or shoulders, matting of mane, tail or hair and excessive scratching or biting. H asini is a sucking louse and severe infestations have been known to cause anemia. A very severe lice infestation can even cause overall loss of condition...although this usually only happens if the infestation goes untreated and is most often seen with horses that are being neglected in general.
It is easy to diagnose lice as the nits and sometimes the lice themselves are visible at the base of the coat hair. However, if you have not dealt with equine lice before, calling the vet for advice is a good idea. An experienced trainer may also be able to help.
The infested horse should immediately be isolated from other horses, as lice readily move from one animal to another. Any horses that were turned out with it should also be inspected for lice. All grooming equipment and tack that has been used on the infected horse should be thoroughly cleaned and disinfected, as nits can sometimes be transported from one animal to another this way. Brushes should have particular attention paid to them.
Unless the horse has a very fine hair coat, it is often recommended to clip a horse when treating lice. This may or may not be necessary in the summer (most lice infestations, however, happen in winter when the coat is thicker).
The horse will then need to be de-loused. Three kinds of lice treatment are available - medicated shampoo, louse powder and louse spray. The life cycle of both species of horse louse is about two weeks, so treatments need to be that often or more often. Follow the instructions on the packaging.
If the infected horse was kept in a stall with the 'deep bed' system, then the bed should be completely removed and redone.
Groom all horses regularly. If you spot lice or nits, treat the horse immediately, even if there are no other symptoms. Horses with very long winter coats are more vulnerable to lice.
Horses in poor overall health are also more likely to become infested. Make sure that your horse has access to a salt lick and consider giving a low dose of Vitamin E, which can help boost the immune system. Garlic also boosts the immune system and keeps off at least some insects.
Keep new horses in quarantine for at least two weeks. Horses that have been rescued or been through an auction, especially a lower end one, should be checked for lice on arrival and again two weeks later.
Most healthy horses never get lice...they are generally seen on neglected animals and the only time I have witnessed them myself was after somebody bought a horse from a livestock auction and turned it out with other horses without quarantine, resulting in several horses in the field picking up 'little visitors'. (And trust me. You never want to have to delouse a horse...)