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Y4 FA - Small ruminants > Sheep skin diseases > Flashcards

Sheep skin diseases Flashcards

1
Q

What are the main economic and welfare problems associated with skin disease in sheep?

A

Pruritis
Weight loss
Fleece

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2
Q

What factors can help diagnose skin and wool disease?

A
  • time of year
  • part of the body affected
  • how many affected
  • pruritis
  • visible parasites
  • other clinical signs
  • previous treatment tried
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3
Q

Contagious pustular dermatitis is also known as…?

A

Orf

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4
Q

What kind of a virus is orf?

A

Parapox vis - Zoonosis

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5
Q

Describe the lesions seen with orf

A
  • Vesicular / proliferative scabby lesions
  • Mouth/head and teats
  • Lambs but can affect ewes too esp teats
  • Painful
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6
Q

What are the impacts of orf?

A
  • Interferes with sucking / eating
  • Teat lesions – predispose to mastitis
  • Poor growth
  • Death
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7
Q

How does orf spread?

A
  • By contact
  • Damage to skin and mouth allows virus in
  • Virus doesn’t survive overwinter outside
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8
Q

How can orf be controlled?

A
  • Isolate clinical cases
  • Disinfect equipment e.g. feeding bottles
  • Care when oral dosing
  • Thorough cleaning and disinfection of buildings, feed troughs, barriers
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9
Q

Describe the orf vaccine and its use

A
  • Only use in infected farms
  • Live vaccine
  • Apply by scratching the skin in the armpit of lambs
  • Don’t use indoors as it will contaminate housing
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10
Q

Name 3 parasitic mites that infect sheep

A
  • Psoroptes ovis
  • Chorioptes bovis
  • Trombicula
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11
Q

Name a lice that infects sheep

A

Bovicola ovis

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12
Q

Sheep scab is caused by…?

A

Psoroptes ovis

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13
Q

How is sheep scab transmitted?

A

Direct contact sheep or infected scab fomites material on fencepost, vehicles etc
Allergic reaction to the mite - 6-8 weeks post infection

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14
Q

How do sheep with scab present?

A
  • Pruritis
  • Nibbling
  • Kicking, scratching, rubbing
  • Wool loss, ragged fleece, moist yellow appearance
  • On flank, dorsal side or whole sheep
  • Sheep stop eating, weight loss, death
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15
Q

Describe how to diagnose sheep scab

A
  • Choose itchiest sheep with wool loss
  • Exudative lesions
  • Edge of lesion
  • Wool pluck (sealed in bag)
  • Skin Scrape (put in container)
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16
Q

Describe the appearance of psoroptes ovis mites and how you would identify them

A

Pointed mouth parts and bell shaped suckers on segmented pedicles

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17
Q

Which test can be used to diagnose sheep scab in the earlier stages?

A

ELISA
- Detects signs in early stages (within 2 weeks of infection)
- Good sensitivity and specificity

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18
Q

What must be considered when treating sheep scab?

A

Survives off host 17-19 days days so must consider re-infection
Must treat all sheep

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19
Q

What are the treatment options for sheep scab?

A

Dexamethosone (steroid) for severely affected sheep
Organophosphate dip – diazinon
Macrocytic lactones

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20
Q

Describe how to correctly administer organophosphate dips to be effective

A
  • Dip replenishment (manufacturers instructions)
  • 1 minute in dip
  • DO NOT USE SHOWERS
  • Do not use synthetic pyrethroid dips
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21
Q

Name 3 examples of macrocytic lactones that can be used for sheep scab treatment

A

Ivermectin
Doramectin
Moxidectin

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22
Q

Which macrocytic lactone cannot be administered with footvac?

A

Moxidectin 1%

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23
Q

How can sheep scab be prevented?

A
  • Biosecurity – don’t buy in
  • Observation not enough (7-8 weeks to see clinical signs)
  • Treat all bought in sheep, sheep grazing away
  • Double fence neighbouring stock
  • Cleansing Disinfection vehicles and equipment, esp. shearers scanners
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24
Q

What are some of the main problems associated with scab management on farms?

A
  • Diagnosis
  • Incorrect products
  • Under dosing because of weight, guns etc…
  • Injection technique
  • Mark when injected
  • Poor dipping technique
  • Re-infection from neighbour, bought in etc.
  • Anthelmintic resistance
25
Q

Is Bovicola ovis a chewing or sucking louse?

A

Chewing

26
Q

Describe the features of a Bovicola ovis infection

A
  • Small pale red brown
  • Permanent parasites
  • Highly host specific
  • Spread via direct contact
  • Chew at skin and coat broad heads feed on skin debris and wool
  • Like a warm, dark environment
27
Q

Which 2 factors reduce the risk of Bovicola ovis?

A

Shearing
Rainfall

28
Q

How can Bovicola ovis be diagnosed?

A

Part fleece on back and flanks hind limbs several wool partings and look for clumps red brown lice
2-3 mm long so visible

29
Q

How can outdoor sheep be treated for Bovicola ovis?

A

Shearing
Heavy Rainfall
Treat worst affected

30
Q

How can indoor sheep be treated for Bovicola ovis?

A
  • Synthetic Pyrethroid Pour ons
  • Concern for resistance
  • Plunge dip diazinon OP dip
31
Q

At what time of year does fly strike most commonly occur?

A

May to October

32
Q

What is the cause of fly strike?

A

Lucillia sericata

33
Q

Describe how infection with Lucillia sericata leads to fly strike?

A
  • Lays eggs in fleece
  • Larva hatch about 12 hours later
  • Proteolytic enzymes
  • Mouth hooks
  • Damage skin
  • Attract other flies
34
Q

What are the main sites affected in fly stike?

A
  • Breech – affected around bum end
  • Body
  • Wounds
  • Feet (foot lesions)
35
Q

How may sheep affected with fly strike appear in the herd?

A
  • Separate
  • Depressed
  • Toxaemia
  • Dead
36
Q

List the risk factors for fly strike

A
  • Temperature: egg laying requires a temp of at least 10 degrees
  • Humidity
  • Rainfall
  • Fleece length
  • Faecal soiling
  • Time of year
37
Q

How is flystrike treated?

A

Synthetic Pyrethroid pour on – kills maggots
Deltamethrin – kills maggots
Clean wound
Supportive care - antibiotics, NSIADs, fluids, house

38
Q

How can fly strike be controlled?

A
  • Control risk factors
  • Worm control
  • Tail docking
  • Shearing
  • Prophylactic use of Insectsides
39
Q

Name the head fly of sheep

A

Hydrotea irritans

40
Q

Peri-orbital eczema is caused by which bacteria?

A

Staphylococcus aureus

41
Q

‘Lumpy wool’ is caused by which bacterial infection?

A

Dermatophilus congolensi

42
Q

How does lumpy wool present?

A
  • Associated with wet conditions esp after shearing
  • Thin wooled breeds
  • Crusty lesions with wool loss
  • Pruritic
  • Confuse sheep scab
  • Risk for fly strike
43
Q

Caseous lymphadenitis is becoming an increasing problem in which group of sheep?

A

Terminal sires

44
Q

What is the name of the bacteria that cause caseous lymphadenitis?

A

Corynebacterium pseudotuberculosis

45
Q

Where in the body is affected by caseous lymphadenitis?

A
  • Affects external & internal lymph nodes - Especially parotid LN
  • Abscesses
46
Q

How is caseous lymphadenitis treated?

A
  • Antibiotic cannot penetrate
  • So no effective treatment
47
Q

How is caseous lymphadenitis spread?

A
  • Close contact
  • Fomites: shearing
  • Respiratory spread (mediastinal LN abscess ruptures into airway)
48
Q

How can CLA be controlled?

A
  • ELISA & clinical examination before ram purchase: identify low risk animals
  • Test and Cull affected animals
  • Vaccine available Reduce incidence but not prevent all infections
  • Biosecurity
  • Hygiene of shearers, mobile dippers, mobile handling
49
Q

Name two diseases/conditions that can cause abnormal wool fibres

A

Border disease
Copper deficiency

50
Q

Name 2 tick species found in the UK

A

Ixodes ricinus
Dermacentaur reticulata

51
Q

What is the main impact of ticks?

A

They are vectors for diseases

52
Q

Name the agent that causes tick borne fever

A

Anaplasma phagocytophilia

53
Q

What are the effects of tick-borne fever?

A

Profound Immuno-suppression
* Gateway infection
* Fever
* Rams in autumn- spermatogenesis infertility
* Ewes in autumn abortion

54
Q

Which agent causes tick pyaemia?

A

Staphylococcus aureus

55
Q

What are the effects of tick pyaemia?

A

Affects lambs
Polyarthritis/joint ill
Immunosuppression

56
Q

Name a viral infection that is transmitted by ticks and is zoonotic

A

Louping ill

57
Q

What are the effects of Louping ill virus?

A

Neurological - Non suppurative menigoencephomyelitis alitis
Varying severity inco-ordination to seizures death

58
Q

How is Louping ill controlled?

A

Vaccine
Tick control
Grazing management

59
Q

Describe the acaricide drugs that can be used to control tick borne infections

A

Diazinon OP plunge dip
* 3-6 weeks protection
Synthetic pyrethroids pour ons
* Varying protections 6- 12 weeks protection

Y4 FA - Small ruminants (18 decks)

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