Difference between revisions of "Psoroptic Mange"

Revision as of 14:15, 1 March 2011

Synonyms

Sheep Scab
Psoroptic scabies
Psoroptosis

Introduction

Psoropitc mange is the disease caused by the non-burrowing mite, Psoroptes ovis (common name Scab mite), which affects sheep.

Other species of Psoroptes mite affect a variety of species including Cattle, Goats, Horse, Rabbit, Camelid, however, all mites are host specific and will be discussed later.

Description: The mite looks very similar in appearance to Chorioptes, being oval in shape with long legs, but is almost visible to the naked eye. It has pointed mouthparts and jointed pedicles which have suckers on the distal aspect.

Life cycle: Egg- Larvae- Nymph- Adult is confined to the skin surface. This life cycle takes around 10 days to complete. Adult female life expectancy is around one month and she lays 2-3 eggs per day, hence a mite population on an animal can expand rapidly. The mite can survive off the host and so transmission via housing and bedding is possible. Most transmission occurs from direct contact such as at markets or in livestock transporters.

Predilection site: Lesions are most common on flanks, neck, back and shoulders

This mite is found worldwide, but has been eradicated from Australia and New Zealand.

Pathogenesis

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 reaction to antigenic mite faeces, by the host. This causes intense pruritus, leading to self trauma, crust and scale formation and inflammation.

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.

Psoroptic mange in sheep is a notifiable disease in the UK

Clinical signs

Severe pruritus
Evidence of self-trauma (loss, damage or staining of wool)
Inflammation with exudate followed by a yellow crust
Weight loss or reduced weight gain in young stock
Secondary bacterial infection or Blowfly strike

Diagnosis

History and clinical signs
Skin scraping to microscopically identify mites (low magnification). Mites are found under scabs and in skin folds

Treatment/ Control

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
Plunge dipping is curative and preventative
- dip must contain the Organophosphate diazinon or the Synthetic Pyrethroid cis-cypermethrin
- plunge dipping must last 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 in the fleece allwing better penetration
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

@@ Line 1: / Line 1: @@
-{{OpenPagesTop}}
+== Synonyms  ==
-Also Known as: '''''Sheep Scab — Psoroptic Scabies — Psoroptosis'''''
-== Introduction  ==
+*Sheep Scab
+*Psoroptic scabies
+*Psoroptosis
-Psoropitc mange is the disease caused by the '''non-burrowing''' mite, ''[[Psoroptes ovis]] ''(common name Scab mite), which affects sheep.
+<br>
-Other species of Psoroptes mite affect a variety of species including cattle, goats, horse, rabbit, camelid, however, all mites are host specific.
+== Introduction  ==
-== Pathogenesis  ==
+Psoropitc mange is the disease caused by the '''non-burrowing''' mite, ''Psoroptes ovis ''(common name Scab mite), which affects sheep.
-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.
+Other species of Psoroptes mite affect a variety of species including Cattle, Goats, Horse, Rabbit, Camelid, however, all mites are host specific and will be discussed later.
-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.
+'''Description''': The mite looks very similar in appearance to Chorioptes,&nbsp;being oval&nbsp;in&nbsp;shape with long legs,&nbsp;but is almost visible to the naked eye. It has pointed mouthparts and jointed pedicles which have suckers on the distal aspect.
-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.
+'''Life cycle''': Egg- Larvae- Nymph- Adult is confined to the skin surface.&nbsp;This life cycle takes around 10 days to complete.&nbsp;Adult female life expectancy is around&nbsp;one month&nbsp;and she lays 2-3 eggs per day, hence a mite population on an animal can expand rapidly. The mite can survive off the host and so transmission via housing and bedding is possible. Most transmission occurs from direct contact such as at markets or in livestock transporters.
-Psoroptic mange in sheep '''used to be a notifiable ''''''disease '''in the UK, but has been de-regulated since 1992.
+'''Predilection site''': Lesions are&nbsp;most common on flanks, neck, back and shoulders
-== Clinical Signs  ==
+This mite is found worldwide, but has been eradicated from Australia and New Zealand.
-'''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.
+<br>
-== Diagnosis  ==
+== Pathogenesis  ==
-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.
+The mite is active in the keratin layer of the skin and has abrasive mouthparts. It&nbsp;feeds on exudate of lymph, skin cells and bacteria caused by a hypersensitivity reaction to antigenic mite faeces,&nbsp;by the host. This causes intense&nbsp;pruritus, leading to self trauma, crust and scale formation and inflammation.
-== Treatment/ Control  ==
+The disease is most prevalent in autumn and&nbsp;winter months, however does still occur in the summer, especially in sheep that have not been shorn.
-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.
+Psoroptic mange in sheep is a '''notifiable disease '''in the UK
-*'''Plunge dipping is curative and preventative'''
+<br>
-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
-''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>
+== Clinical signs  ==
-== Other species ==
+*Severe pruritus
+*Evidence of self-trauma (loss, damage or staining of wool)
+*Inflammation with exudate followed by a yellow crust
+*Weight loss or reduced weight gain in young stock
+*Secondary bacterial infection or Blowfly strike
-'''Cattle'''
+<br>
-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.
+== Diagnosis  ==
-'''Horses'''
-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.
-'''Rabbits'''
-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]].
+*History and clinical signs
+*Skin scraping to microscopically identify mites (low magnification). Mites are found under scabs and in skin folds
-{{Chapter}}
-{{Mansonchapter
-|chapterlink = http://www.mansonpublishing.co.uk/book-images/9781840760491_sample.pdf
-|chaptername = Sheep Scab
-|book = Sheep Medicine
-|author = Philip R. Scott
-|isbn = 9781840761498
-}}
-== References  ==
+== Treatment/ Control ==
-Aitken, I.D, (2007) '''Diseases of Sheep fourth edition,''''' Blackwell Publishing ''
+Infestations are difficult to eliminate from a&nbsp;flock so a key factor in control is to not allow it to enter.
-Fox, M and Jacobs, D. (2007) '''Parasitology Study Guide Part 1: Ectoparasites,''''' Royal Veterinary College ''
+*New stock should be isolated for at least three weeks before mixing with the main flock
+*Plunge dipping is curative and preventative<br>- dip must contain the Organophosphate diazinon or the Synthetic Pyrethroid cis-cypermethrin<br>- plunge dipping must last for at least one minute and the head should be fully submerged twice during this time<br>- the sheep must be kept moving when in the dip as the movement displaces air from in the fleece allwing better penetration
+*Can treat with avermectins or milbemycins by injection
-Hindson, J.C, (2002)''' Manual of Sheep Diseases second edition,''''' Blackwell Publishing ''
-Taylor, M.A, Coop, R.L, Wall, R.L, (2007) '''Veterinary Parasitology third edition,''''' Blackwell Publishing ''
-{{review}}
-{{OpenPages}}
+*Cattle, horses and rabbits
+**No licensed product for horses in the UK
+**Cattle and rabbits can be treated with avermectins, milbemycins or topical acaricides
-[[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]]
+[[Category:To_Do_-_Kate]] [[Category:Integumentary_System_-_Mite_Infections]]