Psoroptes ovis - clinical
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Pathogenesis
- Economically important ectoparasite of sheep
- Causes sheep scab
- Wool loss, restlessness, biting, scratching of infested area and decreased productivity through decreased weight gain
- Usually seen in late autumn and early winter (although may also occur in late summer)
- Population numbers decline after shearing due to a change in the micro-climate, then build up again as the fleece grows
- Notifiable in UK
- Mites found under scabs and in skin folds
- Lesions most common on flanks, neck, back and shoulders
- Causes pruritic condition of cattle
- Active in keratin layer
- Mouthparts abrade the skin
- Antigenic material in mite faeces can lead to hypersensitivity reactions
Diagnosis
- Skin scraping
- KOH added
- Warm slide over a bunsen flame
- Examine under a microscope
Treatment
- Sheep
- Plunge dipping; no less than 1 minute and must dip head at lease once
- Can treat with avermectins or milbemycins by injection
- Cattle, horses and rabbits
- No licensed product for horses in the UK
- Cattle and rabbits can be treated with avermectins, milbemycins or topical acaricides
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