Caused by Psoroptes

  • Occurs in cattle, sheep, horses, goats, rabbits and other animals
  • Host-specific
  • Psoroptes cuniculi in ear canals of rabbits, horses, goats and sheep

Pathogenesis

  • The ears are painful and intensely pruritic
  • Affected rabbits shake their heads and scratch their ears
  • The inner surfaces of the pinnae are covered with brown, scaly, fetid material, and the skin beneath is raw
  • Mites are grossly visible
  • Histologically, there is chronic erosive and proliferative eosinophilic dermatitis
    • The mites are non-burrowing and thus are found only in the exudate, not in the tissue


Diagnosis

  • Microscopic examination for mites (low magnification)
  • Appearance


Control

  • Infestations are difficult to eliminate from a colony
    • Ivermectin is usually effective.


  • P.equi at base of mane, tail and forelock in horses
  • P.ovis in sheep (sheep scab)and cattle
    • Thickened skin and dry scales and crusts
    • Starts at withers and spreads due to self trauma
    • Microscopically:
      • Spongiotic, hyperplastic or exudative superficial perivascular dermatitis
      • Eosinophils


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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