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Controlling Lice in HorsesBy Kentucky Equine Research Staff · July 13, 2017

The infestation of a horse with lice, called pediculosis, need not cause panic or alarm. However, treating affected horses and avoiding future infestations can be frustrating. Here are five fast facts about lice and how to handle an infestation.

1. Two types of lice infest horses, biting (Haematopinus asini) and sucking (Damalinia equi). Each type typically infests different parts of the horse with biting lice more commonly found on the forehead, neck, and lateral thorax, and sucking lice preferring the mane, dock of the tail, fetlocks, and inner gaskins.

2. Lice spread easily between horses in close contact. Although horses have some natural immunity against lice, just like they have some natural immunity against internal parasites, some risk factors exist, including:

  • High stocking density;
  • Sharing blankets, brushes, and other equipment between horses;
  • Poor feed quality;
  • Gestational status;
  • Underlying health issues;
  • Longer body hair (e.g., winter coat, feathering); and
  • Season (infestations are more common in winter and early spring).

3. Unlike ticks, no known diseases are transmitted between lice and horses. Further, most types of lice are species-specific, meaning that horse lice do not typically infest humans. One exception to this “rule” is the poultry-chewing louse. When horses and poultry are housed in close contact, horses can become infested.

4. Even though no specific diseases are transmitted between louse and horse, lice infestations can be itchy! Horses can cause skin trauma and hair loss by rubbing and biting. Further, extremely heavy infestations with sucking lice can cause anemia, a decrease in circulating red blood cells.

5. Treatment options include various medications (imidacloprid, phoxim, selenium sulfide, triflumuron, permethrin combined with dimilin or pyriproxyfen, fipronil) as well as neem seed extract. Recently, one research group* reported that “a single application of the 10 mg/mL deltamethrin preparation was effective and safe in the treatment and in the prevention of lice infestation in these horses. It was also effective in preventing new infestations for one month.”

“As listed above, nutrition plays an important role in minimizing the chances of lice infestation. In addition to a nutritional consultation, consider supplementing your horses with Bio-Bloom PS (in Australia, look for Bio-Bloom). This product provides lecithin and essential fatty acids that help maintain healthy skin and a shiny hair coat,” advised Kathleen Crandell, Ph.D., a nutritionist for Kentucky Equine Research (KER).

*Castilla-Castaño, E., A. Vischi, C. Navarro, et al. 2017. Control of lice infestation in horses using a 10 mg/mL deltamethrin topical application. Irish Veterinary Journal. Jun 19;70:22.