Sheep lice and keds Flashcards Preview

Parasitology - Ectoparasites > Sheep lice and keds > Flashcards

Flashcards in Sheep lice and keds Deck (29)
Loading flashcards...
1

What are the symptoms of Psoroptes ovis? Which species does it affect?

Intense itching, rubbing, scratch, nibbling
Sheep - rarely cattle and horses

2

What are the distinguishing features of Psoroptes ovis?

Pointed mouth
Long setae (hair like strucutres)
Long legs
Jointed pedicles with 3 part trumpet
Thumb print pattern on dorsum (all mange mites)

3

How long do Psoroptes mites live for? How many eggs do they lay? How long is their life cycle?

1 month
100
16 days

4

Are Psoroptes burrowing or non-burrowing?

Non-burrowing - feed at surface of skin

5

What are all mange mites sensitive to? What type of fleece does this mean they struggle to survive on?

Sensitive to desiccation
Struggle to survive on longer fleece

6

What are Psoroptes lesions like? Where are the mites found?

Inflammation, serous exudate, scale and crust. Centre is thick and crusty, vesicle ruptures to form moist yellow pustule
Mites found on moist skin at edge of resin

7

Psoroptes lesions spread rapidly and cover most of the body in weeks. What does this cause?

Chronic exudative superficialities dermatitis

8

Describe the pathogenesis of psoroptes ovis?

Type I hypersensitivity due to antigens in mite faeces
Causes chronic skin changes, hyperkeratosis, aural haematomas, intense irritation, decreased weight gain, seizures, death

9

How is psoroptes ovis diagnosed?

Clinical signs, skin scraping

10

What is sheep scab also known as? What is it caused by?

Psoroptic mange
Psoroptes ovis

11

What are the symptoms of sheep scab?

Pruritic, irritation
Scratching against walls
Wool loss
Weight loss
Stood alone
Depressed
Wool in mouth

12

What can be used to test for Sheep scab?

Nibble reflex - sheep respond to back scratching with lip and tongue movements

13

How is sheep scab transmitted?

Direct contact, contaminated environment, fomites

14

How long do Psoropes ovis survive off the host?

2 weeks

15

What introduces sheep scab to a flock?

Poor fencing, mixing flocks, contaminated lorries

16

What season is Sheep Scab usually seen?

Autumn/Winter
Shearing in Summer reduces population

17

Where are the sites of mites on sheep, that act of reservoirs?

Axilla (armpit)
Ears
Skin folds

18

What is the treatment for Sheep scab?

OPs - dip in Diazinon
Injectable MLs - ivermectin

19

What species of Psoroptes is found in rabbits? Where is it usually localised and what does it cause?

Psoropotes cunicoli
Ears - causes mange in auditory canal

20

Where about on sheep do Chorioptes bovis usually affect?

Lower limbs, abdomen

21

What are the 3 species of lice found in sheep? Which is biting and which is sucking?

Damalinia ovis (body louse)
Linognathus pedals (foot louse)
Linognathus ovillus (face louse)

22

What are the symptoms of lice in sheep?

Restlessness, rubbing, stopping feeding, wool loss if heavy infestation

23

What do lice lesions attract?

Blowflies

24

How are lice controlled in sheep?

Shearing
Quarantine
Remove wool rom housing

25

What is the weird looking half tick half lice? What species is this?

Sheep keds
Melophagus ovinus

26

What is the morphology of sheep keds?

Flattened like lice
Short legs with stout claws
5mm
True flies but no wings

27

Where do larvae of Melophagus ovinus develop?

Inside female
Become pupa in wool
Emerge 2-5 weeks later

28

How are sheep keds transmitted? What do they cause?

Direct contact
Pruritis, loss of condition

29

What season are sheep keds usually present? Do they transmit pathogens?

Winter
Transmit non-pathogenic Trypanosoma melphagium