Small Ruminants: Skin and Ectoparasites

Question 1

1. What pathogen casues orf?
2. How does orf present?
3. What is the problem with orf?
4. How is it spread?

Answer 1

1. Parapox virus
2. Vesicular/proliferative scabby lesions- mouth/head and teats (4-6 week duration)
3. Painful- interferes with suckling, eating, predisposes to mastitis
4. Spread by contact- damage to skin and mouth allows virus in- rough grazing

Question 2

1. How is orf controlled?
2. What vaccine is available?

Answer 2

1. Isolate clinical cases, disinfecting bottles, dosing guns etc
2. Live- can cause disease (don’t use in unaffected farms), apply by scratching skin
   Do not use indoors- will contaminate housing

Question 3

What three mites can affect sheep?

Answer 3

Psoroptes ovis
Chorioptes bovis
Trombicula (harvest mites)

Question 4

1. What mite causes sheep scab?
2. How is it transmitted?
3. How long does it take for extreme pruritis?
4. What are the clinical signs?

Answer 4

1. Psoropted ovis
2. Direct contact or infected scab fomites- material on fencepost
3. 6-8 weeks
4. Kicking, scratching, rubbing, wool loss, ragged fleece, moist, yellow appearance

Question 5

What can sheep scab potentially lead to in extreme cases?

Answer 5

Proggresively distressed
Stop eating causing severe weight loss and seizures

Question 6

How is it diagnosed?

Answer 6

• Choose itchiest sheep
• Exudative lesion
• Edge of lesion- wool pluck, skin scrape
• Warm sample
• Microscope

Pointed mouth parts and bell shaped sucker

Question 7

What can be done if the skin scrapes are negative, but it is still believed to be scab?

Answer 7

Could be due to low numbers
* Sample again
* Send to veterinary lab agency
* ELISA- detects early stages

Question 8

When is the ELISA sheep scab test useful?

Answer 8

• Useful for an individual animal
• Biosecurity/quarentine protocols
• Whole flock testing- 12 sheep

Question 9

Why is sheep scab very difficult to get rid of?

Answer 9

Survives off host for 17-19 days
Reinfection from environment easy

Question 10

How is sheep scab treated?

Answer 10

• Dexamethasone for severely affected sheep
• OP- diazanon dip
• ML:
  Ivermectin- 2 doses days apart, not sufficient, must move to clean
  Doramectin- 1 dose, must move
  Moxidetin 1%- 2 doses 10 days appart, don’t need to move
  Moxidectin 2%- single dose, don’t move

Withdrawal times vary

Question 11

How can sheep scab be prevented?

Answer 11

• Biosecurity
• Observation not enough
• Treat all bought in sheep- sheep grazing away
• Double fencing
• Cleansing, disinfection

Question 12

What are common problems with sheep scab and treatments?

Answer 12

• Diagnosis
• Incorrect product
• Underdosing
• Injection technique
• Poor dipping technique

Question 13

1. Where on the sheep does chorioptes bovis affect more commonly?
2. What can it cause in rams?
3. How is it treated?

Answer 13

1.
* Ventral abdomen
* Scrotum
2. Can cause infertility in rams due to increased blood flow from irritation therefore altering temperature of testes
3. OP dips

Question 14

What parasite that affects sheep does this image show?

Answer 14

Bovicula ovis

Question 15

What are the increased risks and decreased risks of lice infestation?

Answer 15

Increased:
* Housing- warm dark, dry

Decreased:
* Shearing reduces risk
* rainfall

Question 16

How can lice be checked for?

Answer 16

Part fleece on:
* Back
* Flanks
* Hindlimbs
Look for clumps of red brown lice- 2-3mm long so visible

Question 17

How is lice in sheep treated?

Answer 17

Outdoors- shearing, rainfall, treat worst affected
Housed- synthetic pyrethroid pour ons, OP dip

Question 18

How can scrapie present?

Answer 18

Usually neurological but can present as primary skin disease

NOTIFIABLE

Question 19

1. When is fly strike most common?
2. What species of fly causes it and how?

Answer 19

1. Common in may to october
2. Lucillia sericata-
   Lay eggs in fleece
   larva hatch 12 hours later
   proteolytic enzymes and mouth hooks damage the skin
   Attracts other flies

Question 20

1. What can fly strike potentially cause?
2. What are the risk factors?
3. How is it treated and controlled?

Answer 20

1. Can develop toxaemia and die
2. RF- temp, humidity >65%, faecal soiling, carcass on farm
3. TX- early treatment, kill maggots (SP pour on, deltamethrin), clean wound, supportive Abs, NSAIDs, house
   Control- shearing, dagging, worm control, tail docking, lameness control, prophylactic insecticides

OP dip
Pyrethroid pour ons
IGRs 8-16 weeks

Question 21

1. What is the name for the head fly?
2. Where are head flys found?
3. How are they controlled?

Answer 21

1. Hydrotea irritans
2. Horn base, ocular (discharge)
3. Treat- OP dips, Pyrethroid pour ons, IGRs

Question 22

How long do the following treatments last against flies?
OP dips
Synthetic pyrethroid pour ons
IGRs

Answer 22

• OP dips- 8-10 weeks
• Synthetic pyrethroids pour ons- 8-16 weeks
• Insect growth regulators- 8-16 weeks

Question 23

What is ovine sweet itch?

Answer 23

Uncommon
Hypersensitivity to midges

Question 24

1. What is lumpy wool?
2. What are the risk factors?
3. What does it cause?
4. How is it treated?

Answer 24

1. Bacterial infection of dermatophilus congolensi
2. Wet conditions after shearing, thin wooled breeds
3. Crusty lesions with wool loss
4. Penicillin 3-5 days

Question 25

What does the following image show? How is it spread and treated?

Answer 25

Peri-orbital eczema- staphylococcus aureus Spread by contact- feeding troughs Treat with penicillin

Question 26

1. What causes caseous lymphadenitis in sheep? 2. Where does it affect? 3. What does it cause? 4. Why is there not effective treatment? 5. How is it spread and diagnosed? 6. How is it controlled?

Answer 26

1. Corynebacterium pseudotuberculosis 2. Affects external and internal lymph nodes- parotid 3. Abscesses 4. Antibiotics cannot penetrate abscesses 5. Spread- close contact, fomites, resp. Diagnosis- culture, ELISA 6. Test and cull, hyigene, vaccine available (not completely preventable) Purchase isolate and test ELISA, hyigene of shearers, mobile dippers, handling

Question 27

What does this image show? What causes it?

Answer 27

Ringworm Trichophyton verrucosum

Question 28

What does the following image show? What can cause this?

Answer 28

Photosensitisation St Johns wort ingestion

Question 29

What not infectious causes can cause wool loss?

Answer 29

Thin or broken fibres Natural shedding Woolbreak- stress

Question 30

What are the two likely causes of abnormal fibres in sheep?

Answer 30

Border disease- pestivirus (hairy shakers) Copper deficiency- growing lambs

Question 31

1. In what conditions do ticks feed? 2. Where are they typically found? 3. Where else can they be found and why? 4. What diseases can they act as a vector for?

Answer 31

1. >85% humidity, >7 degrees 2. Traditionally upland and western UK 3. Lowland farm microclimates- ditches, forests 4. Tick born fever, tick pyemia, louping ill, q-fever (abortion), babesiosis (cattle), lyme disease

Question 32

1. What causes tick borne fever? 2. What does it cause in sheep?

Answer 32

1. Anaplasma phagocytophilia 2. Profound immuno-supression gateway infection Rams in autumn- spermatogenesis infertility Ewes in autumn- abortion Do become immune

Question 33

1. What causes tick pyemia? 2. What does it cause in lambs?

Answer 33

1. Mechanical transmission of staphylococcus aureus 2. Polyarthritis/joint ill or spinal abscess Immunosupression

Question 34

1. What does looping ill cause pathologically? 2. What are the clinical signs 3. What is the morbidity? 4. How can it be controlled? | Viral infection

Answer 34

1. Non-supprative meningioencephomyelitis 2. Varying severity from inco-ordination to seizures and death 3. Morbidity- 5-60% 4. Protective immunity in colostrum, vaccine, tick control, grazing

Question 35

How can tick control be done with animals?

Answer 35

Care with new born and naive * Don't expose to tick area for first time if pregnant * pasturella pneumonia vaccine * Looping ill vaccine

Question 36

What drugs can controll ticks?

Answer 36

* Diazinon OP dip 3-6 weeks * SP pour ons- varies- 6-12 weeks