Too many of us have experienced this scenario: the winter arrives, and your cob, with their beautiful long feathers starts to stamp, bite, and itch their legs at any given opportunity, due to an invisible pest. This, frustrating situation is caused by infestation of Chorioptes equi- more commonly known as the feather mite. They are often diagnosed on the limbs of feathered horses, but it is important to recognise that they can migrate to any part of the body and trouble any equid.
Chorioptes equi are specifically adapted to spend their entire 2-to-3-week life cycle on the top layer of the skin, where movement and feeding on skin debris causing itchiness and irritation. As miniscule parasites, measuring about 0.3mm in length, they cannot be seen with the naked eye, but many people refer to ‘walking dandruff’- loose flakes of skin which become caught in the feathers, which leads to suspicion that the horse may be infected with mites. In many cases there may only be very mild symptoms, or no signs at all, with reactions being triggered only when there are thousands of mites living on the skin surface. However, some horses are ‘hypersensitive’ and have severe reactions to a small infestation. Whilst the mites themselves don’t cause lesions, self-trauma due to persistent itching may lead to the development of scabby areas, or even bleeding on the horse’s leg.
- If you call your vet out, once the issue is diagnosed, you will often see them reach for a bottle of injectable wormer (Doramectin).The treatment protocol involves two injections, two weeks apart, given under the skin or into muscle.
- Topical treatments are also used to kill the mites. If this approach is taken you must ensure that the legs are soaked in the product otherwise the medication will not work, meaning that this can be an expensive and labour-intensive option.
- Washes which contain permethrin are also available. These will kill some of the mites, but don’t appear to be powerful enough to fully treat the infestation. Other options such as Lime Sulphur washes will also reduce the number of mites, if used weekly, however many people are deterred from using it as the shampoo smells of rotten eggs.
Whilst the good news is that infestations are treatable, elimination of the mites from the environment is challenging, so reinfection is common. Management changes are therefore important, including disinfection of stables, bedding, boots etc. and switching from straw to rubber matting or shavings. Not only does the straw harbour mites, but it may also be abrasive on sore legs. Finally, clipping off the feathers is, in some cases the only way to get treatment to penetrate through, killing the mites, effectively treating infestation.
For more information about specific treatments available, please call our team on 01323 815120.