Difference between revisions of "Psoroptic Mange"

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Caused by [[Psoroptes]]
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Also Known as: '''''Sheep Scab — Psoroptic Scabies — Psoroptosis'''''
 
  
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== Introduction  ==
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*Occurs in cattle, sheep, horses, goats, rabbits and other animals
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*Host-specific
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*[[Psoroptes cuniculi|''Psoroptes cuniculi'']] in ear canals of rabbits, horses, goats and sheep
  
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Psoropitc mange is the disease caused by the '''non-burrowing''' mite, ''[[Psoroptes ovis]] ''(common name Scab mite), which affects sheep.
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'''Pathogenesis'''  
  
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Other species of Psoroptes mite affect a variety of species including cattle, goats, horse, rabbit, camelid, however, all mites are host specific.
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*The ears are painful and intensely pruritic
  
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== Pathogenesis  ==
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*Affected rabbits shake their heads and scratch their ears
  
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The mite is active in the keratin layer of the skin and has abrasive mouthparts. It feeds on exudate of lymph, skin cells and bacteria caused by a [[Hypersensitivity - Introduction|hypersensitivity reaction]] to antigenic mite faeces by the host. This causes '''intense pruritus''', leading to self trauma, crust and scale formation and inflammation.
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*The inner surfaces of the pinnae are covered with brown, scaly, fetid material, and the skin beneath is raw
  
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It is not only economically important to the sheep industry due to poor fleece quality and weight loss, but it can also pre-dispose to life-threatening condition such as [[Blowfly Strike|Blowfly strike]], as the [[Calliphoridae|blowflies]] find the damaged skin ideal for egg laying.
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*Mites are grossly visible
  
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The disease is most prevalent in autumn and winter months, however does still occur in the summer, especially in sheep that have not been shorn.
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*Histologically, there is chronic erosive and proliferative eosinophilic dermatitis
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**The mites are non-burrowing and thus are found only in the exudate, not in the tissue
  
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Psoroptic mange in sheep '''used to be a notifiable ''''''disease '''in the UK, but has been de-regulated since 1992.
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<br>'''Diagnosis'''  
  
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== Clinical Signs  ==
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*Microscopic examination for mites (low magnification)
  
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'''Severe pruritus and '''evidence of '''self-trauma '''(loss, damage or staining of wool) are the main signs to notice from within the herd. Once a closer inspection is made, inflammation and an exudate will be noticed on the skin and areas of yellow crust will also be present. In on-going cases,'''weight loss''' in adults, or reduced weight gain in growing animals, will be seen due to the irritation causing them to have a reduced feed intake. In some cases, secondary '''blowfly strike '''may by the first sign noticed, when the sore traumatised skin has become a perfect breeding ground for the blowfly.
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*Appearance
  
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== Diagnosis  ==
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<br>'''Control'''
  
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History and clinical signs are often enough to make presumptive diagnosis. Skin scraping to microscopically identify mites (low magnification) should be performed. Mites are found under scabs and in skin folds.
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*Infestations are difficult to eliminate from a colony
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**Ivermectin is usually effective.
  
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== Treatment/ Control  ==
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<br>
  
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Infestations are difficult to eliminate from a flock so a key factor in control is to not allow it to enter - new stock should be isolated for at least three weeks before mixing with the main flock.
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*[[Psoroptes|''P.equi'']] at base of mane, tail and forelock in horses
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*[[Psoroptes ovis|''P.ovis'']] in sheep ('''sheep scab''')and cattle
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**Thickened skin and dry scales and crusts
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**Starts at withers and spreads due to self trauma
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**Microscopically:
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***Spongiotic, hyperplastic or exudative superficial perivascular dermatitis
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***Eosinophils
  
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*'''Plunge dipping is curative and preventative'''
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<br>
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The dip must contain the '''Organophosphate, diazinon '''or the '''Synthetic Pyrethroid, cis-cypermethrin. '''The sheep must be dipped for '''at least one minute '''and the head should be fully submerged twice during this time. The sheep must be kept moving when in the dip as the movement displaces air from the fleece allowing better penetration
 
  
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''Psoroptes'' can be treated with avermectins or milbemycins by injection, but only moxidectin has any prophylactic effect. Two injections 7 days apart or one single dose (doramectin only) are needed. <br>
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=== Pathogenesis  ===
  
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== Other species ==
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*Economically important ectoparasite of sheep
  
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'''Cattle'''
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*Causes '''sheep scab'''
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**Wool loss, restlessness, biting, scratching of infested area and decreased productivity through decreased weight gain
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**Usually seen in '''late autumn''' and '''early winter''' (although may also occur in late summer)
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**Population numbers decline after shearing due to a change in the micro-climate, then build up again as the fleece grows
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**'''Notifiable in UK'''
  
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Psoroptic mange is uncommon in cattle in the UK. When present, it affects mainly the withers and can be treated with avermectin, milbemycins or topical acaracides.
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*Mites found under scabs and in skin folds
  
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'''Horses'''
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*Lesions most common on flanks, neck, back and shoulders
  
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Equine Psoroptic mange is '''notifiable in the UK''', but has not been recorded for many years. There are no licensed products for treatment of horses in the UK.
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*Causes pruritic condition of cattle
  
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'''Rabbits'''
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*Active in keratin layer
  
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Rabbits become infected by ''[[Psoroptes cuniculi]]'' causing [[Mites – Rabbit#Psoroptiasis|'Ear canker']]. The external auditory canal infection is often asymptomatic, but may cause scratching and head shaking behaviour. It can be treated with avermectin, milbemycins or topical acaracides. For more information see the [[Mites – Rabbit#Psoroptiasis|rabbit section]].
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*Mouthparts abrade the skin
  
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*Antigenic material in mite faeces can lead to hypersensitivity reactions
  
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{{Chapter}}
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=== Diagnosis  ===
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{{Mansonchapter
 
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|chapterlink = http://www.mansonpublishing.co.uk/book-images/9781840760491_sample.pdf
 
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|chaptername = Sheep Scab
 
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|book = Sheep Medicine
 
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|author = Philip R. Scott
 
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|isbn = 9781840761498
 
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}}
 
  
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== References  ==
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*Skin scraping
  
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Aitken, I.D, (2007) '''Diseases of Sheep fourth edition,''''' Blackwell Publishing ''
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*KOH added
  
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Fox, M and Jacobs, D. (2007) '''Parasitology Study Guide Part 1: Ectoparasites,''''' Royal Veterinary College ''
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*Warm slide over a bunsen flame
  
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Hindson, J.C, (2002)''' Manual of Sheep Diseases second edition,''''' Blackwell Publishing ''
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*Examine under a microscope
  
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Taylor, M.A, Coop, R.L, Wall, R.L, (2007) '''Veterinary Parasitology third edition,''''' Blackwell Publishing ''
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<br>
  
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=== Treatment  ===
  
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{{review}}
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*Sheep
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**Plunge dipping; no less than 1 minute and must dip head at lease once
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**Can treat with avermectins or milbemycins by injection
  
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{{OpenPages}}
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*Cattle, horses and rabbits
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**No licensed product for horses in the UK
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**Cattle and rabbits can be treated with avermectins, milbemycins or topical acaricides
  
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[[Category:Expert_Review - Farm Animal]][[Category:Expert Review - Horse]] [[Category:Integumentary_System_-_Mite_Infections]][[Category:Dermatological Diseases - Sheep]][[Category:Dermatological Diseases - Cattle]][[Category:Dermatological Diseases - Horse]]
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[[Category:To_Do_-_Kate]][[Category:Integumentary_System_-_Mite_Infections]]

Revision as of 13:05, 1 March 2011

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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