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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'''Pathogenesis'''
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*The ears are painful and intensely pruritic
  
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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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*Affected rabbits shake their heads and scratch their ears
  
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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 inner surfaces of the pinnae are covered with brown, scaly, fetid material, and the skin beneath is raw
  
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== Pathogenesis  ==
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*Mites are grossly visible
  
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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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*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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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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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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'''Diagnosis'''
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*Microscopic examination for mites (low magnification)
  
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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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*Appearance
  
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== Clinical Signs  ==
 
  
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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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'''Control'''
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*Infestations are difficult to eliminate from a colony
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**Ivermectin is usually effective.
  
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== Diagnosis  ==
 
  
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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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*[[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[[Category:To_Do_-_Clinical]]
  
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== Treatment/ Control  ==
 
  
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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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*'''Plunge dipping is curative and preventative'''
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===Pathogenesis===
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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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*Economically important ectoparasite of sheep
  
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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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*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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== Other species ==
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*Mites found under scabs and in skin folds
  
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'''Cattle''' 
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*Lesions most common on flanks, neck, back and shoulders
  
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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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*Causes pruritic condition of cattle
  
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'''Horses'''
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*Active in keratin layer
  
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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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*Mouthparts abrade the skin
  
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'''Rabbits'''
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*Antigenic material in mite faeces can lead to hypersensitivity reactions
  
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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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===Diagnosis===
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*Skin scraping
  
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*KOH added
  
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{{Chapter}}
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*Warm slide over a bunsen flame
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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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*Examine under a microscope
  
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Aitken, I.D, (2007) '''Diseases of Sheep fourth edition,''''' Blackwell Publishing ''
 
  
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Fox, M and Jacobs, D. (2007) '''Parasitology Study Guide Part 1: Ectoparasites,''''' Royal Veterinary College ''
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===Treatment===
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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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Hindson, J.C, (2002)''' Manual of Sheep Diseases second edition,''''' Blackwell Publishing ''
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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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Taylor, M.A, Coop, R.L, Wall, R.L, (2007) '''Veterinary Parasitology third edition,''''' Blackwell Publishing ''
 
  
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[[Category:To_Do_-_Clinical]]
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{{review}}
 
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{{OpenPages}}
 
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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]]
 

Revision as of 11:43, 9 July 2010

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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