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Introduction
All species are thought to be affected by the same strain of mite Chorioptes bovis.
Pathogenesis
Chorioptes' mouthparts do not pierce the skin and they feed on skin debris and exudate, meaning its pathogenic significance is mild.
In cattle, economic significance is the main factor as infestation can cause damage to the hide by self trauma.
Clinical Signs
Cattle and Small Ruminants
The disease in these species is usually very mild and not often noticed by stockmen. Signs that are noticed include rubbing and scratching of the affected area and damage to the hide (often not seen until after slaughter).
Typically affected areas are the base of tail, perineum and the udder, as well as legs of sheep and goats.
Horses
The disease is more noticable in horses, with them shaking, scratching, rubbing, stamping and biting the affected areas regularly. Crusty skin lesions on the pastern, fetlock and cannon are a common manifestation as well as thickening of the skin and loss of hair in chronic cases.
The problem is worse in colder months and mud can exacerbate the problem to lead to exudative proliferative dermatitis with secondary bacterial infection (greasy heel) in severe cases.
Diagnosis
History and clinical signs are often used to make a presumptive diagnosis.
A skin scraping from the edge of a fresh lesion will often demonstrate the presence of the mite under a microscope.
Treatment
Always clip the affected area.
There are no products currently licensed for treatment of Chorioptes. The list below contains a number of products that have been reported effective
Topical
- 1% Selenium sulphide shampoo - whole body shampoo
- Fipronil (Frontline spray) - on affected area
Systemic
- Ivermectin, paste for horses, good to eliminate the mite in a group infestation.
Treat all in-contact animals and disinfect bedding, housing and any shared tack (horses).
References
Brown, C.M, Bertone, J.J. (2002) The 5-Minute Veterinary Consult- Equine, Lippincott, Williams; Wilkins
Fox, M and Jacobs, D. (2007) Parasitology Study Guide Part 1: Ecotparasites Royal Veterinary College
Lloyd, D.H, Littlewood, J.D, Craig, J.M, Thomsett, L.R. (2003) Practical Equine Dermatology, Blackwell Science
Taylor, M.A, Coop, R.L, Wall, R.L, (2007) Veterinary Parasitology third edition, Blackwell Science