Chorioptes in horses is not known to be zoonotic.
Host range and geographic distribution
Life cycle - direct
Life Cycle: Chorioptes equi
Pathology and clinical signs
Infection with C. equi is more common than is clinical disease. Mites of the genus Chorioptes, unlike Psoroptes, do not penetrate the skin during feeding, but depend instead on debris on the skin surface. Nevertheless, the mites can cause severe pruritus. Some horses with large mite burdens do not show clinical signs. The mechanisms underlying this apparent tolerance are not known.
Clinically, the most common site for lesions of chorioptic mange is the lower limbs, especially in heavily feathered animals. The pruritus caused by the mites leads to attempts to relieve the irritation by scratching, rubbing and biting the affected areas, foot stamping and kicking. These activities may result in damage to the haircoat and skin. Papules, with exudation of serum and scabbing may occur, together with matting of the haircoat. In non-feathered horses, Chorioptes may infest the tail head and other regions of the body, with similar clinical effects. Chorioptic mange in horses is seen as a clinical problem more often in winter than at other times of the year.
The recovery of adult mites, or even fragments, from hair and coat brushings, or from skin scrapings, confirms the diagnosis.
Treatment and control
There are no products approved for horses in Canada that are effective for chorioptic mange, but ivermectin (VARIOUS) and moxidectin (QUEST and QUEST PLUS) have been used extralabel, either orally or applied directly to the lesions. These treatments cannot be relied upon, however, to remove all the mites or resolve all the clinical signs. In some cases, shaving of the affected areas and application of a keratolytic cream may be as effective as an acaricide. All horses in a group should be treated, ideally weekly for three weeks and then monthly for three months.
Additional information on the products mentioned is available from the Compendium of Veterinary Products (Twelfth Edition, 2011), or from the manufacturers.
Control of chorioptic mange in horses depends on rapid diagnosis and treatment, with particular attention to new arrivals in a group, and cleaning of any potential fomites, for example tack.